Plant morphology final exam

Secondary phloem functions

1. conduction of water and carbohydrates; 2. support of young twigs and other newly formed woody stems (because of numerous phloem fibers, if present); 3. secretion, numerous secretory structures are often present; probably involved with defense against herbivores and pathogens; 4. storage of various substances, including carbohydrates and nitrogenous compounds; 5. avenue for gas exchange with the deeper tissues (vascular cambium and secondary xylem);6. protection of underlying tissues; and7. production of sequent periderms (usually produced from the secondary phloem).

Light absorption by leaves Palisade mesophyll cells generally have 1.5 to ____times as many chloroplasts as spongy mesophyll cells. This is an adaptation to the higher light intensities that are encountered by cells on the upper surface of the leaf. However, some light still manages to pass to the layers of cells below the palisade mesophyll. The ____is the phenomenon where light passes through the first layer of cells without being absorbed. Multiple layers of photosynthetic cells increase the likelihood that any given photon eventually will be absorbed. Light passing through the leaf may be reflected off of various objects, light may pass between the aqueous volume of mesophyll cells and the air spaces that surround them and be bent by refraction, or the light may be scattered when it strikes objects with similar diameters to its wavelengths. Reflection, refraction, and scattering increase the effective path that light can travel through the leaf, and hence, the likelihood that a given photon will be absorbed.

2.5 ; sieve effect ;

Many monocots with perennial leaves have fiber bundles and fibrovascular bundles in their leaves. A few monocots, some members of the yam family (Dioscoreaceae), have compound leaves. Petiolate leaves with a broad lamina and reticulate venation are rare in monocots. It was once believed that most monocots had leaves that are modified to form phyllodes. ____ are actually petioles that have become broadened and flattened, and replace the lamina as the primary photosynthetic portion of the leaf. However, it is now generally accepted that most monocot leaves are true leaves (not just petioles), but basically consist of a broad and flattened midvein with essentially no ____ (the midvein functions as the lamina would).

Phyllodes; lamina

Some leaves appear compound, but are really simple. ____ leaves are simple leaves that grow as a single, continuous lamina, but which later tears apart and appears compound [palms (Arecaceae) and bananas (Musaceae)]. These leaves have predetermined areas of weakness that facilitate the tearing. The tearing is normal in the development process of the leaf. 93 ______ leaves are typically very hard and contain much sclerenchyma (are sclerophyllous). This helps to prevent animals from exploiting them as a source of water and food. Leaves can be tightly placed against one another along their length, and actually appear to be a stem. These stemlike aggregations of leaves are referred to as ____. The above ground "stems" of bananas are actually pseudostems.

Pseudocompound; Xeromorphic; pseudostems

Gymnosperm leaves The leaves of cycads (Cycadophyta) are similar to those of eudicots. Leaves of cycads are compound. A small amount of secondary xylem is produced in the midvein. The leaves of cycads and some other gymnosperms have what is known as transfusion tissue, which is comprised of transfusion tracheids and sometimes transfusion parenchyma. The transfusion tracheids are located around the vascular tissues of the bundles. These tracheids are very short and wide. The transfusion tissue extends to an endodermis. The leaves of cycads have both palisade and spongy parenchyma, but between the palisade and spongy parenchyma tissues is an area of _____ transfusion tissue, which is comprised of horizontally oriented transfusion tracheids. The two types of transfusion tissues are interconnected and function to move water out to the mesophyll.

accessory;

The leaves of some submerged aquatic species and nonphotosynthetic, _____, parasitic species do not have stomata at all. The upper epidermis typically has a _____ cuticle than the lower epidermis. The epidermal cells typically have thin cell walls, except those that occur at the leaf margins. These epidermal cells tend to have thicker cell walls and a sclerenchymatous hypodermis occurs beneath them. This arrangement reinforces the leaf and prevents wind-induced_____. A hypodermis may or may not be present in other areas of the leaf below the epidermis. When present, it is often most prominent over the major veins, especially the____ or midrib; in these areas it is often collenchymatous.

achlorophyllous; thicker;tearing; midvein

6. aquatic plants tend to have much ______ tissue, and an internal ventilation system to transport oxygen to all areas of the plant. 7. an endodermis in the leaves and stems. 8. fibers are present in aquatic plants exposed to wave action or ______ in order to minimize tearing and damage. 9. leaves are often _____, filamentous, or finely dissected. Plants that occur in habitats that are neither extremely dry, nor extremely wet are referred to as ______.

aerenchyma; current; linear; mesophytes

a. ____ roots: produced on above ground portions of the plant. b. ____ roots (also known as radial roots, nodal roots, or crown roots): a type of aerial root used in support and stabilization of the stem in many monocotyledonous plants (for example, corn, Zea mays). 7. storage roots: used to store a variety of substances, including carbohydrates, nutrients, and water. These may also be used for perennation and asexual reproduction (Ipomoea batatas, sweet potato). 8. _____: negatively gravitropic extensions of the root system that grow up and out of water or waterlogged soil; most likely for aeration of the root system, and possible support and stabilization of the plant.

aerial; prop; pneumatophores

3. _______ bundle: xylem tissue completely surrounds the phloem; occur in some species of monocots (Acorus). The secondary bundles of at least some woody monocots are also amphivasal (Cordyline). 4. _____ bundle or amphiphloic bundle: phloem tissue surrounds the xylem; occur in some angiosperms, often in the filaments of the anthers, and some ferns (Polypodium). 5. U-shaped bundles and V-shaped bundles: xylem is arranged in the shape of a U or a V, respectively; occur mostly in _____; uncommon. Bundles that have procambial tissue between the xylem and phloem are referred to as _____, whereas bundles that do not have procambial tissue between the xylem and phloem are referred to as closed. In closed bundles, the phloem is directly adjacent to the xylem. Plants with closed bundles typically do ____ undergo secondary growth. Bundles with fibers. These may or may not contain vascular tissue: 1. _____ bundle: contains xylem and phloem, but the outermost cells are differentiated as fibers (Cordyline; Yucca).

amphivasal; amphicribral; monocots; open; not; fibrovascular

The same plant can undergo both types of dilatation growth (Aristolochia). A high level of ______ cell division and tangential cell enlargement produce dilated phloem rays (Fig E 14.16). Usually only some rays undergo dilation. Phloem rays and xylem rays are produced by the _______of ray initials in the vascular cambium. In the non-conducting phloem, the sieve tubes no longer conduct and become crushed or filled with gasses. Parenchyma cells often enlarge and compress the sieve tube members. Sometimes the parenchyma cells invade the sieve tube members and form ______. Parenchymatous epithelial cells also form tylosoids when invading intercellular _______. Tylosoids are similar to tyloses. The parenchyma cells in the non-conducting phloem store starch and persist until they are cut off from their water supply by a sequent periderm.

anticlinal; same sets; tylosoids; resin ducts;

The _______ of the cauline bundles in the node can differ dramatically from that of the internode. Examples: 1. branches (bridges) connecting individual bundles. 2. a network of bundles. 3. complete plate of vascular tissue. 4. mass of irregular tracheary elements (xylem _____). A similar phloem glomerulus would also be present in these nodes. From primary to secondary growth The fascicular cambium occurs between the primary phloem and primary xylem of an _____ vascular bundle, and it is what remains of the procambium after the primary phloem and xylem were formed (differentiated). The formation of the fascicular cambium from the procambium residual tissue precedes the formation of the interfascicular cambium. The interfascicular cambium forms in the interfascicular region through dedifferentiation of some of the parenchyma cells in that region. Remember meristematic cells are really just parenchyma cells

arrangement; glomerulus; open;

The portions of the vascular cambium to the inside of the primary phloem become active _____ the pericyclic portions. Eventually, the circumference of the cambium becomes more or less _____ in cross section. The vascular cambium now functions normally, producing secondary phloem to the _____ and secondary xylem to the inside. Rays are often initiated in the portions of the vascular cambium formed from the _____. Other portions of the cambium can also produce rays. The formation of the periderm follows the initiation of secondary growth. The cells of the pericycle undergo periclinal and anticlinal division. The periclinal divisions cause an increase in the number of pericyclic layers producing what is known as a ______ pericycle. The first periderm arises in the outer layers of the proliferated pericycle. The cortex and epidermis are ruptured and are cast off as the root continues to expand its diameter (Fig)

before; circular; outside; pericycle; proliferated;

Root hairs may only have a minimal value for the direct absorption of water and essential elements from the soil. Instead, root hairs may facilitate absorption by altering the ______ and environment of the soil around the root (this region is known as the ______, which consists of the root hairs, the layer of soil bound to the root by the mucigel, sloughed cells from the rootcap, and a variety of microorganisms). In most plants, mycorrhizal fungi are associated with the root system. In roots that have a persistent epidermis, the epidermal cells may become heavily cutinized or lignified. This provides protection from pathogen invasion and desiccation. Sometimes the epidermis of roots is referred to as a ______ and the cortex of roots is sometimes known as an _____. In some species, especially in some epiphytes, a multiple epidermis known as the velamen is produce

chemistry; rhizosphere; rhizodermis; epiblem

9. photosynthesis. Some species have no functional leaves, and their photosynthetic stems are referred to as ______ [Asparagus spp. (Asparagaceae)]. Some species of plants have stems that are almost indistinguishable from leaves [some species of Phyllanthus (Euphorbiaceae) and Phyllonoma (Grossulariaceae)]. In some species [pencil tree (Euphorbia tirucalli)], the leaves are small and ephemeral, and the stems are green and carry out most of the photosynthesis.

cladophylls, cladodes, or phylloclades;

Types of vascular bundles based on the arrangement of the vascular tissues (the particular vasculature pattern of a given bundle is independent of the position of the bundle in the stem): 1. ______ bundle: contains one patch of xylem and one patch of phloem, and the phloem generally occurs to the periphery of the xylem (Medicago; Ranunculus; Zea). 2. _____ bundle: xylem is flanked by phloem on both sides. The phloem tissue to the periphery is termed external phloem, whereas the phloem tissue adjacent to the pith is referred to as internal phloem (formerly known as _____ phloem) (Cucurbita). Sometimes the internal phloem is more or less independent of the rest of the vascular bundle. Sometimes the external phloem is independent of the xylem. Phloem ______ are sieve tubes that form lateral connections between internal and external phloem in stems, longitudinal vascular bundles in internodes and petioles, and the abaxial and adaxial phloem in leaves.

collateral; bicollateral; intraxylary; anastomoses;

Secondary phloem in conifers Conifer phloem is generally less _____ than that of angiosperms. The axial system contains _______cells. Some of these parenchyma cells may be differentiated into albuminous cells. Fibers and sclereids also may be present. Fibers, when present, usually occur as uniseriate _______ bands (Metasequoia). These bands of fibers alternate with similar bands of parenchyma cells and sieve cells (Fig E 14.1 a). The rays are usually uniseriate and contain parenchyma cells and sometimes albuminous cells (Taxus) and/or tannin cells (Pinus). If albuminous cells are present, they are located on the margins of the rays.

complex; sieve cells and parenchyma; tangential;

Secondary phloem can be storied or nonstoried. The sieve tube members in species with nonstoried phloem tend to have _______, whereas those in species with storied phloem usually have sieve plates with a few sieve areas or only one. Phloem rays resemble xylem rays and can be uniseriate or multiseriate. The rays are usually comprised of parenchyma cells, but can contain sclereids or sclerified parenchyma cells (_______). Crystals are often present in cells of the rays.

compound sieve plates; sclerotic parenchyma

In eudicots, the parenchyma cells between the new vascular cylinder of the lateral root and the metaxylem of the axial root can differentiate to form tracheary elements that will establish a vascular ____ between the lateral root and the original root. In monocots that have numerous vascular bundles and pith in their roots, the lateral roots are able to form ____ connections with several of the vascular bundles. The connections can also include the deeper metaxylem vessels in the pith if the parenchyma cells of the pith differentiate into tracheary elements. Lateral roots often form in clumps of ____ to three or more at the same level. If the root is curved, lateral roots typically form on the ____ side. Lateral root primordia usually arise from partially differentiated ____ cells. In pericyclic and endodermal cells of corn (Zea mays), the cells thin their walls and lose lignin.

connection; xylary; two; convex; pericycle

In palms with pinnate leaves, the pseudopetiole is _____ into the rachis. In palms with palmate leaves, the pseudopetiole ends at the lamina, and a ligulelike structure occurs at this point. This structure is known as the ____. Perennial monocot leaves can have multiple abscission zones [palms (Arecaceae)]. Fern leaves The leaves of ferns are similar in arrangement to those of eudicots. The leaves of ferns always have a petiole, and are usually compound. 100 Most fern leaves have _____ branched venation, whereas the leaves of most eudicots have reticulate venation. Fern leaves also have chloroplasts in their epidermal cells. The vascular bundles are always _____.

continuous; hastula; dichotomously; collateral

5. ____ roots: prop roots to some extent and other roots that after extending through the soil and becoming anchored, the uppermost portions contract. Contraction is caused by changes in the shape of the _____ cells, which simultaneously expand radially and shorten up to one-half to two-thirds of their height. This is how seedlings of many species, and bulbs and corms are ____ down into the soil to the appropriate depth. Many species of monocots and some eudicots have contractile roots. 6. _____ roots: form on organs other than roots, most common on the lower ______ of the stems of monocots; also formed on the stems of many plants when the stem comes in contact with suitable substrate (may also be formed on leaves in certain species). These are the roots that form on cuttings of leaves and stems of many plants (important in propagation of many types of plants).

contractile; cortical; pulled; adventitious; nodes

2. _____ bundle: vascular bundles, other than leaf traces, that occur in the cortex. Their exact function(s) is currently unknown. 3. ____ bundle: vascular bundles that run through the pith. They may be complete and contain xylem and phloem, or contain only phloem tissue. They can form complex patterns of vasculature and contribute to leaf vasculature. In members of the Cactaceae family, the medullary and cortical bundles are connected via horizontal bundles that run through the medullary rays. 4. ______: bundles that move out from the cauline bundles (or other bundle types) through the stem and into the leaf. These are often present in the cortex, and can be confused with cortical bundles. It is important to note that cauline bundles, cortical bundles, and medullary bundles can have different arrangements of the vascular tissues contained within. Example, a cauline bundle can be collateral, bicollateral, amphivasal, or amphicribral.

cortical; medullary; leaf traces;

In some eudicots that have a very thick cortex, the leaf traces also can move upward in the stem some distance before entering a leaf and appear as vascular bundles in the cortex (appear as ____ bundles). These are simply leaf traces and are not the same thing as cortical bundles. Nodes and internodes The stems of all seed plants and ferns produce repeating arrangements of structures known as ______ (a single phytomere consists of a leaf, node, internode, and axillary bud). The point at which vegetative or reproductive lateral appendages (one or more leaves and axillary buds, along with reproductive structures, if present) attach to the stem is referred to as a _____. The stem segment between two nodes is referred to as an internode (Fig). Each node will usually have one or more axillary buds, and one or more leaves. At the node, the axial vasculature _____ to the lateral vasculature (vasculature of leaves or branches). Along the internode only stem tissue is present.

cortical; phytomeres; node; connects

In lianitic species of Bauhinia and in Prestonia macrocarpa, this irregular cambial growth causes stems to be _____ (cross-shaped) in transverse section. The stem is at first round, then through unequal growth of the vascular cambium on two opposite sides, the stem assumes a _____ shape over time. On two of the sides, the cambium becomes less _____, while on the alternate sides it becomes much more active. In the slower growing regions, all of the cells produced by the vascular cambium remain ______. In the regions where the cambium is rapidly producing tissues, a high proportion of vessel elements with large diameters are produced (Figs M 18.3, 4). This type of growth allows these lianas to increase _____, but still remain flexible.

cruciate; flattened; active; small; conductivity

3. Anomalous placement of the vascular cambium In this type of secondary thickening, parenchyma cells in various locations _____ and become meristematic, producing vascular cambia in irregular places. In Ipomoea (Convolvulaceae), secondary growth initiates as the ______. Later, numerous additional cambia arise, and form around isolated vessel elements or groups of vessel elements. These new cambia produce conducting tissues to _____ sides, although both the xylem and phloem have large amounts of parenchyma. In this newly formed xylem where vessels occur or are clustered, more additional cambia can be produced. This process of additional cambium formation can continue indefinitely (Figs M 18.5,.6). In several genera of the Valerianaceae family, fascicular cambia extend towards the ___, encircling the xylem in the vascular bundle. These cambia then produce irregular amounts of xylem and phloem, and the bundle becomes _____ (star-shaped) in cross section.

dedifferentiate; common type; both;pith ; stellate

Unifacial leaves Many species of monocots have unifacial leaves. Unifacial leaves have only one side _______. Examples include: onion (Allium), Iris, sweet flag (Acorus), and Sansevieria. The leaf primordium forms as it does in bifacial leaves. The adaxial meristem becomes much more _____ than it does in bifacial leaves, and marginal meristems are not formed. The lamina consists of only a thickened midvein. In ensiform (sword-shaped) leaves that are flattened from side to side, expansion is almost completely radial. In cylindrical leaves, expansion in both width and thickness occurs. In onions, as radial expansion occurs, the mesophyll is torn, and this tearing is what gives rise to the hollow center of the leaf.

developmentally; active;

2. ______: stele appears as a series of bundles separated by many leaf gaps. Leaves are positioned close together on the stem. Each of the amphicribral bundles that are formed in this condition are sometimes referred to individually as a _____ (Polypodium). B. ectophloic siphonostele: phloem is only exterior to the xylem. An ectophloic siphonostele always appears to be comprised of _____ bundles. Occurs in some ferns (Osmunda), and all (gymnosperms and angiosperms) seed plants. 1. _____: vascular bundles are usually arranged in a ring towards the periphery of the stem. Stele of eudicots and gymnosperms. 2. _____: vascular bundles are arranged in a scattered pattern throughout the stem. Stele of monocots. Some monocots have roots with atactosteles (Dracaena) or eusteles (Smilax).

dictyostele; meristele; separate; eustele; atactostele;

4. Successive cambia Successive cambia are formed, function for a limited time, and then ____. These cambia are determinate. New cambia arise later from parenchyma cells that dedifferentiate and were originally produced by the once living cambium. In Iresine (Amaranthaceae), an initial cambium arises and functions in the common type of secondary growth. After a period of producing normal secondary tissues, the cambium becomes inactive and its cells _____. At this point, the cambium ceases to exist. In the outermost regions of the newly produced secondary phloem, a new cambium is formed. This cambium is a normal, bidirectional cambium. It now functions normally for a limited time, then stops, its cells differentiate, and it ceases to be a cambium. Later, from some of the newly formed parenchyma cells in the phloem, another new cambium forms again, and the cycle starts all over. This process is repeated again and again.

die; differentiate;

The root primordia grow out quickly as root spurs and form root hairs over the entire surface. Once available water is gone, the root spurs ___ back almost to the surface of the parent root. Prior to death, the root spurs produce new _____ that later can regrow the spur. Root spurs are only known to occur in the Cactaceae family (Mauseth 13.18). Plants in the family Proteaceae produce specialized lateral roots known as proteoid roots. ______ roots are short lateral roots that produce an abundance of rootlets. These rootlets greatly increase the ability for uptake of nutrients. Plants that produce proteoid roots grow in areas with nutrient _____ soils. Presumably, proteoid roots are produced when roots encounter areas of the soil with ____ nutrient reserves. The root-shoot transition region The primary tissues of the shoot are arranged _____ than those of the root. The exarch xylem and independent phloem strands of the root must be made to merge with the endarch xylem into the typical collateral bundles of the shoot.

die; primordia; Proteoid; deficient; higher; differently

Anomalous thickening and secondary growth in monocots Secondary thickening in monocots occurs either through ___ growth or through _____ meristems. Lateral meristems can act developmentally in the following ways: 1. the lateral meristem is limited in extent and _____ activity after root formation (some herbaceous species), 2. the lateral meristem remains active for a limited period of time after root formation and contributes to the formation of the plant body (some herbaceous species), and 3. the lateral meristem remains active throughout the life of the plant and contributes to the __---_ of the plant body (secondary growth); typical of arborescent woody species.

diffuse; lateral; ceases; majority

In older parts of the phloem, the rays may become dilated in a process known as _______, which occurs in response to the increasing circumference of the stem or root (Fig E 14.16). The increase in circumference is caused by the addition and accumulation of _______ tissue by the vascular cambium. Cells produced form dilatation growth form _______ tissue. The production of dilatation tissue keeps the stem from tearing, and instead, allows it to expand circumferentially to keep pace with the expanding secondary xylem. There are two types of dilatation tissue: 1. _______ tissue: formed from isolated parenchyma cells in the cortex or from axial parenchyma in the secondary phloem. 2. _______ tissue: formed from parenchyma cells in the rays of the secondary phloem.

dilatation or dilatation growth; secondary xylem; dilatation; expansion; proliferation

As the lateral root begins to form its own ____, parenchyma cells at the point of origin of the lateral root differentiate to form a new endodermis that connects the endodermis of the parent root to that of the lateral root. Dimorphic roots In most root systems, the primary root and the lateral roots are _____ in structure. In some plants, the root system is comprised of more than one type of root, with each type of root having its own structure and function. Root ____ are specialized lateral roots that form in some species that occur in xeric environments where water is only temporarily available. Within the primary root are located several lateral root primordia that can be activated when water becomes available.

endodermis; similar; spurs

Roots which have only an endodermis have two distinct apoplastic compartments: 1. _______Those with an exodermis have three: 1. epidermis, 2. cortex, and 3. vascular cylinder (Fig). In species of the genus Citrus (Rutaceae), the cells of the exodermis completely cover their walls with a suberin lamella, destroying the ____ connections and the cells die. Passage cells remain to allow for transport of materials into the cortex. Vascular cylinder or stele: Root steles are almost always _______. (the different stele types will be discussed later). The outer most region of the vascular cylinder is known as the _____. Pericycle cells are usually just parenchyma cells. Sometimes some of the cells of the pericycle can be fibers. The pericycle may be one (usual case) to several cell layers in thickness (this occurs in some Poaceae, Arecaceae, and the genera Smilax and Salix). Occasionally the pericycle is absent.

epidermis and cortex and 2. the vascular cylinder. ; plasmodesmatal; protosteles, eusteles, or atactosteles; pericycle;

2. secondary thickening meristem: a lateral meristem or "vascular cambium" that gives rise to secondary ground tissues (secondary cortex and/or conjunctive tissue) and secondary vascular tissue in the form of secondary vascular bundles. These two meristems are not ______ to the vascular cambium in gymnosperms and woody eudicots. The primary thickening and secondary thickening meristems may not be distinct from one another, but the secondary thickening meristem may develop ______ the primary thickening meristem.

equivalent; from

Leaf abscission An abscission zone occurs in almost all _____ leaves. The zone is usually visible as a _____ or constriction around the petiole. Sometimes it is a different color than the rest of the petiole. In sessile leaves, the abscission zone may be the only remnant of the petiole. The abscission zone consists of two parts: 1. abscission layer or ____ layer: functions to ensure the abscission of the leaf, and to define the point of rupture. This layer consists of a plate of small, thin-walled cells that are oriented transversely across the petiole. The vascular bundles contain fewer fibers in this region, and the vessels are not continuous across it. The middle lamella and cellulose of the cell walls is degraded in the cells of the abscission zone prior to leaf drop.

eudicot; groove; separation;

In the stems of seed plants, the primary phloem is also ______, but the primary xylem is ______ (development from the inside outward, away from the center; the protoxylem is towards the inside, adjacent to the pith, and the metaxylem is towards the outside). Stems in the primary state of growth have endarch xylem (Fig). In the stems of some ferns (ex. Pteridium), mesarch xylem occurs. In mesarch development of the xylem, there are several vascular strands, and the xylem in the center of each matures first. Thus, the protoxylem would be flanked on either side by metaxylem, and therefore metaxylem development is both ______ (Fig). In the stems of a few types of ferns (ex. Selaginella and certain extinct species of ferns), centrarch xylem occurs. In centrarch development of the xylem, the protoxylem is at the center of a single strand or patch of xylem and the metaxylem is towards the outside. Centrarch xylem development is only _____ (Fig).

exarch; endarch or centrifugal; centripetal and centrifugal; centrifugal

The arrangement of the phloem is similar to that of the xylem; it is _____, with the protophloem to the exterior and the metaphloem closest to the center or the xylem. The protophloem has protophloem ____ (the first phloem to mature in the root) that are similar in concept to the protoxylem poles of the protoxylem. In the root, the xylem and phloem are always separated by a band of parenchyma. If the root does not undergo secondary growth, much of this parenchyma may become _____. Phloem fibers are rare in roots. Branch roots or lateral roots Lateral roots form endogenously and the _____ is the main contributor to lateral root formation. However, occasionally stelar parenchyma cells and cells of the endodermis may also become mitotically active and contribute to lateral root formation. In most ferns and fern allies, the ______ is the source of lateral roots, not the pericycle.

exarch; poles; sclerified; pericycle; endodermis

Cortex The cortex of roots is comprised primarily of ground tissues. It is variable in thickness. The outer portion can be modified to form an _____, and the innermost layer is the _____. Most of the cortex, other than the exodermis and endodermis, is comprised of parenchyma cells. Intercellular spaces are more common and the cortex is usually _____ in roots than in stems. In some species that produce roots that are exposed to sunlight, cortical cells will develop _____. In roots that do not undergo secondary growth, many of the cells of the cortex will develop into ______ cells. In grasses, the cortex is short-lived and the endodermis or the pericycle becomes the ____ barrier of the root. After loss of the cortex, cells of the endodermis, the pericycle, and the _____ parenchyma (those parenchyma cells in the vascular cylinder) may become highly lignified.

exodermis; endodermis; narrower; chloroplasts; sclerenchyma; outer; stelar

In plants with compound leaves, the leaflets close when the adaxial cells of the pulvinus contract (this region of the pulvinus is known as the _____), and open when the abaxial cells contract (this region is known as the ____) (Fig). Motor cells in the flexor region ____ turgor during closure and lose turgor during opening. Thus, the swelling (___ of turgor by) of the extensor motor cells and the shrinkage (loss of turgor by) the flexor motor cells straightens the pulvinus, and opens or ____ apart leaves or leaflets. The changes in turgor are caused by the movement of potassium ions (K+1) ____ the contracting cells to the expanding ones. Water follows passively along the gradient of solutes that is produced. Water flows into the expanding cells (those that gain potassium ions) from the contracting cells (those that are experiencing a loss of potassium ions). The contraction or expansion is caused by changes in turgor pressure

extensor; flexor; gain; gain; spreads; from;

Because the new cambia arise external to most of the new secondary phloem produced by the previous cambium, these cambia produce secondary xylem _____ to this phloem. Thus, the stem is comprised of alternating concentric rings of xylem and phloem. Secondary phloem that is located interior to secondary xylem is referred to as _____ phloem (formerly known as _____ phloem; Fig M 18.7). This process also occurs in the Chenopodiaceae, Menispermaceae, and Convolvulaceae families. In Bouginvillea (Nyctaginaceae), included phloem also is produced, but in a somewhat different fashion. The result is included phloem in isolated _____ surrounded by xylem tissue (Fig M 18.8). The cambia in this example do not differentiate and cease all at once, thus giving rise to the above described pattern of secondary tissues.

exterior; included; interxylary; patches;

Anomalous secondary thickening mechanisms The common type of secondary growth (we have been discussing it for a while now), involving a vascular cambium, occurs in all gymnosperms and most of the woody dicotyledons. Patterns of anomalous secondary growth Eudicotyledons 1. Death of the cambium In this type, portions or strips of the cambium die and cease _______, while other portions remain alive and continue to produce secondary tissues (Zygophyllum, Fumaria thymifolia, and Artemisia tridentata). Species that exhibit this type of anomalous growth occur in _____ habitats. During times of extreme drought, little or no water is conducted to some of the cells of the cambium (water conduction stops in narrow strips of wood). The cambial cells fed by the xylem tissue in these strips do not receive enough water to survive and thus _____.

functioning; xeric; die

These large bands of parenchyma are essentially _____. They cause the stem to be weak and sometimes splitting occurs in these areas. If splitting does occur, the stem forms normal ______ and seals off the exposed areas. Variation two (Passiflora and Ambrosia dumosa): In these species, the vascular cambium produces only _______ tissues, but the relative proportions of each tissue vary in different regions of the vascular cambium (Fig M 18.2). In some areas, large amounts of xylem are produced, which push the cambium ______ rapidly.

giant rays; wound periderm; secondary conducting; outward

Palisade cells do not absorb as much light as would be expected. The cells act partially as light _____, where some light is channeled through the intercellular spaces between the mesophyll cells. This is another way to increase the amount of light reaching the lower layers of photosynthetic cells, and keep the upper layer or layers of cells from being over irradiated. Leaf vascular system The vascular system in leaves functions to: 1. transport water ____ the leaf from the stem. 2. distribute water and other substances throughout the mesophyll. 3. transport _____ into the stem from the leaf. 4. ____ the mesophyll cells to allow for gas exchange between them and the leaf atmosphere. 5. provide some structural support

guides; into; photoassimilates; hydrate;

16. parasitism [parasitic plants have roots or portions of their roots modified to form ______ (si. haustorium)]. Haustoria are specialized organs of the parasite that allow it to penetrate the host plant, and subsequently tap into vascular tissues of the host. Species in the parasitic Viscaceae (mistletoe family) have modifications of their root systems known as sinkers or _______ [especially well developed in the dwarf mistletoe (Arceuthobium), where unlike the sinkers of other Viscaceae species that maintain their morphological integrity, the tissues of the sinkers produced by dwarf mistletoes form a complex _____ of host and parasite cells]. Sinkers are portions of the endophytic, rootlike system produced in at least some types of mistletoe species. Sinkers have a primary haustorium at their ____. The root systems of species in the Viscaceae are referred to as a haustorial system or ____ system. 17. housing of symbiotic organisms (symbiotic nitrogen fixing bacteria and mycorrhizal fungi).

haustoria; secondary haustoria; admixture; apex; endophytic;

The large amount of intercellular space that occurs in the spongy mesophyll is important for: 1._____ the likelihood that CO2 will stay in the leaf once it has diffused into it._____ spaces or substomatal chamber (large intercellular spaces) typically occur just to the inside of the stoma (these can occur is stems also). The accumulation space increases the likelihood that a given CO2 molecule once in the leaf will stay there until it is taken up by a mesophyll cell. 2. increases the_____ of the leaf. 3. possibly____ the circulation of gasses in the leaf. In isobilateral leaves, the spongy mesophyll occurs between an upper and lower layer of palisade mesophyll, or in some isobilateral leaves, a typical spongy mesophyll is not present. Instead, there is only one or two layers of small, noncolumnar cells.

increasing; Accumulation; flexibility; increases

Xerophytic leaves Xerophytes are plants that show well developed xeromorphic characters, and tend to occur in environments where water is scarce. Xeromorphic leaves typically have one or more of the following characteristics (at least some of these characters may be influenced by the environment): 1. a thick, dense, waxy cuticle. 2. a thick-walled epidermis and hypodermis. 3. a dense indument (covering) of trichomes, especially on the lower surface of the leaves. 4. sunken stomata, or stomata at the base of stomatal crypts. Stomatal crypts are _____ or depressions in the surface of the leaf. 5. salt glands for the secretion of excess solutes. 6. reduced surface area; often thick and fleshy, often smaller and sometimes cylindrical. 7. mesophyll cells are often packed tightly together.

indentations;

Any cells, including transfer cells, companion cells, and other parenchyma cells in the phloem of a minor vein, that serve as a connection between the photosynthetic tissue and the sieve element system, are known as _____ cells (Fig). Two types of intermediary cells can be recognized: 1. A-type intermediary cells are companion cells that have _____ ingrowths most developed on all walls except those that contact the sieve tube member where numerous plasmadesmatal connections occur; and 2. B-type intermediary cells are parenchyma cells, which are not companion cells, and have labyrinthine ingrowths on all walls and these are most _____ on those that contact the sieve tube member/companion cell complexes. Each vein is surrounded by a sheath of tight-fitting parenchyma cells known as a ____ sheath. The sheath cells of minor bundles that are transfer cells are classified into two types. A-type sheath cells are the _____ cells of the sieve tube members. These cells have wall ingrowths on all sides. B-type sheath cells are not companion cells, and they have wall ingrowths that are most developed on the side that ____ the sieve tube member.

intermediary; labyrinthine; prominent; bundle; companion; contacts

The vascular strands in an internode tend to run up and down the stem, with little branching or fusion. At the nodes, cauline bundles move out ____ the leaves and buds, and bridging bundles unite adjacent cauline bundles. The arrangement of the vasculature in the node is much more complex than that of the internode. In ferns, the vasculature in the cauline bundles departs from the bundle and forms a strand of vasculature that enters the leaf known as a _____. The patch of parenchyma above the point of departure of the leaf trace is known as a _____ (Fig). Cauline bundles can have numerous leaf traces arise from them. In seed plants, the area above the leaf trace is also marked by an area of parenchyma tissue, and this is known as the______ (Fig). The leaf gaps of ferns and the leaf trace gaps of seed plants are not homologous, so thus receive different names

into; leaf trace; leaf gap; leaf trace gap;

In monocots, the cauline bundle pattern is somewhat different. The cauline bundles gradually move ______ toward the center of the stem. At the innermost point, they turn abruptly outward, and branch to give off leaf traces that enter leaves. The cauline bundle also sends out numerous _____, and then turns upward again. These bridges connect this particular cauline bundle with other cauline bundles (Fig). The traces at each node overlap the cauline bundle because the cauline bundle moves upward through one or more nodes. Each leaf also receives numerous traces. The leaf traces can also move upward some distance before entering a leaf, and can superficially resemble cauline bundles. The combination of these characteristics produces the appearance of numerous cauline bundles scattered throughout the ground tissue in the stem (Fig).

inward; bridges;

The living regions grow around these portions of dead tissue, which causes curving or arcing of the vascular tissue, forming acute arcs of secondary tissue. The living bands of cambium can remain alive for years, and over time will also have sections die. This is simply a survival mechanism for extreme conditions and produces a very _______ wood (Fig M 18.1).

irregular

In some species, the palisade parenchyma occurs on both the upper and lower sides of the leaf (Dianthus). In a few species, the palisade parenchyma only occurs on the lower or abaxial side of the leaf. Leaves in which the upper and lower surfaces are similar are termed______. Leaves in which the upper and lower surfaces are different are termed_____. Isobilateral leaves often occur on submerged aquatic species. In these species, the mesophyll is homogenous, not being differentiated into palisade and spongy mesophyll. Many temperate grasses also____ palisade (mesophyll) parenchyma. Between the palisade parenchyma and the lower epidermis is a second type of mesophyll known as spongy mesophyll or spongy parenchyma. This mesophyll tissue has large intercellular spaces, and the_____ is often larger than the symplast.

isolateral or isobilateral; bifacial or dorsiventral; lack; apoplast

New cambia Most monocots _____ secondary growth. Monocots, including: Cordyline, Dasylirion, Dracena, Sansevieria, and Yucca (Agavaceae), some species of Aloe (Aloeaceae), some species of tree grasses (Xanthorrhoeaceae), and some species of Liliaceae, develop a woody secondary body. Typically, the secondary thickening meristems of these species develop as broad bands of meristematic cells exterior to the outermost fibrovascular bundles of the shoot. Prior to lateral meristem formation, meristematic activity occurs throughout that region. Once the meristem forms, the secondary tissues produced to the outside consist of parenchyma cells and are known as ______ cortex. To the inside, the meristem also produces parenchyma cells. Most of these form conjunctive tissue. Some of the cells in the conjunctive parenchyma may form thick lignified walls.

lack; secondary;

Sometimes the term _____ is used in place of leaf trace gap. The number of leaf traces and leaf trace gaps can vary depending on plant species, and the particular location of a node on the same plant. If a given leaf is associated with one gap (lacuna), the node is termed _____; three gaps (three lacunae), the node is termed trilacunar; or more than three gaps, the node is multilacunar. If more than a single leaf occurs at a node, the node is characterized (number of lacunae) with reference to only one of the leaves. If a leaf has more than one trace and also three or more gaps, the central gap is termed the ______ gap (as the central trace is termed the median trace). The other gaps are termed _____ gaps (Fig). Nodes can also be viewed as one-trace, two-trace, three- trace, or multitrace, and combinations between trace and gap terminology are also sometimes used—unilacunar-three-trace, etc.

lacuna; unilacunar; median; lateral;

The apical portion of this sheath grows outward to form the ____. The young lamina initially grows through diffuse mitotic activity, which establishes a parenchymatic primordium. This primordium is a ____ meristem and new leaf tissue is produced from it. Later, rapid elongation occurs. Elongation is initiated at the leaf apex and proceeds basipetally. At this point, stomata appear in the epidermis, chlorophyll is synthesized in the mesophyll, and the metaphloem and metaxylem begin to differentiate. 104 Leaves that develop in this way are _____. These leaves reach a predetermined length, and then the basal meristem disorganizes and growth stops. Other types of monocots have leaves that grow for a longer period of time. The distal portion of these leaves is mature and active photosynthetically, whereas the proximal portion is still growing and immature.

lamina; basal; determinate;

The amount of nonfunctional phloem present varies depending on species. In species where non-conducting phloem accumulates, growth rings are sometimes detectable in the phloem (Tilia). Early formed sieve tube members are _____, whereas those formed later in the growing season are smaller. Sometimes a band of sclerenchyma is formed in the late phloem. The delimitation between the layers of phloem is often obscured because of changes that occur in the non-conducting phloem.

larger;

The cauline bundles will also branch to form branch traces where buds develop. The branch traces are actually leaf traces that run to the first leaves (prophylls) of the _____ branch that the branch traces enter (Fig). The branch traces usually diverge from their cauline bundle right and left of the subtending leaf trace. The branch trace also has its own gap, known as a branch ____ (Fig). Because the branch trace diverges on either side of the leaf trace, the gap is common to both branch and leaf traces (Fig).

lateral; gap

Secondary phloem (bark) Secondary phloem, as does the secondary xylem, consists of both an axial and radial system. Generally, much _____ secondary phloem is present than secondary xylem. The amount of secondary phloem produced by the vascular cambium is usually less than the amount of secondary xylem produced. The older secondary phloem is generally ______and eventually gets separated from the living portion of the plant by one or more sequent periderms. Thus, over time, secondary phloem tissue generally does not accumulate into appreciable amounts, but is instead periodically sloughed off and lost.

less; non-conducting ;

This may allow the cortex and pith of some cacti to be much larger than they are in typical non-succulent plants. In seed plants, three basic arrangements of the primary vascular bundles can be recognized (Fig). 1. vascular bundles are arranged next to each other and form an almost complete ring (Tilia). The interfascicular regions are very narrow. 2. vascular bundles form a ring, but are separated by a fairly wide portion of interfascicular parenchyma (Sambucus; Medicago). The regions of interfascicular parenchyma are referred as interfascicular regions, pith rays, or _____ rays. In the interfascicular region, it is difficult to determine where the ground tissues of the cortex end and those of the pith begin.

medullary;

Mesophyll All of the leaf tissues other than the epidermis and the veins are collectively known as______. The mesophyll of the leaf is continuous with the____ of the stem. In most leaves that are dorsiventral, immediately below the epidermis is the palisade mesophyll or palisade parenchyma. This tissue is comprised of columnar parenchyma cells. The palisade parenchyma can be one or more layers thick (multiple layers are common in______). This tissue is responsible for most of the photosynthesis that occurs in these leaves. 94 These cells have a large central vacuole, and the chloroplasts are pushed up against the plasmalemma. Each cell is separated from the others by very narrow intercellular spaces on most of its sides. In some species, contact between the palisade parenchyma cells is minimized because of small projections or lobes on the cell. Some contact areas between the palisade cells, and the palisade cells and the epidermis is necessary because much of the water movement between the cells occurs via a_____ system. This is important because most palisade cells are not in direct contact with a vein.

mesophyll; cortex; xerophytes; capillary

In some plants that have perennial leaves, a vascular cambium may arise in the _____ and produce a small amount of secondary tissues. The amount of primary vascular tissues in the midvein can be extensive. The midvein can contain more than one vascular bundle. 97 The larger veins can contain numerous cell types, including xylem parenchyma and a more substantial bundle sheath. The bundle sheath of larger veins is usually comprised of _____ cells, but sclereids and fibers can also occur. The larger bundles of some species have winglike extensions of cells known as bundle sheath _____ that extend from the bundle to one or both epidermises. These extensions can be comprised of parenchyma and/or sclerenchyma. They are believed to be important in moving water from the veins to the mesophyll.

midvein; parenchyma; extensions;

Loading and unloading of the veins with sugars from photosynthesis occurs mostly in the smallest veins known as _____ bundles or minor veins. The minor veins can end abruptly at a mesophyll cell, or interconnect two larger veins. The minor veins always contain ____ xylem tissue. The secondary thickenings of the tracheary elements are ____. In the veins that just end in parenchyma tissue, the last several tracheids do not contact each other. They are large and often irregularly shaped. These tracheids are known as ___ tracheids, and are believed to function as a water reservoir and not for water transport. Primary phloem may or may not be present in the minor veins. If it consists of sieve tube elements, companion cells may or may not be present. Many of the parenchyma cells of the minor veins are actually _____ cells. In some plants, the phloem of the minor veins is comprised of only ____ cells, and phloem loading must occur in the next larger set of veins (Fig). Vein loading and unloading can also happen in larger veins.

minor; primary; annular or helical; terminal; transfer; parenchyma

3. vascular bundles are arranged throughout (scattered) the ground tissues. This is the condition common to ______. The ground tissue surrounding the vascular bundles is known as _____ tissue. In stems with this type of vascular bundle arrangement, often the ground tissue cannot be distinguished as cortex and pith. Monocots also have conjunctive tissue in the roots that surrounds individual xylem vessels or clusters of vascular tissue (can be parenchymatous or sclerenchymatous). Three dimensional arrangement of vascular bundles in the stem The simplest arrangement is where each cauline bundle remains ______ of all others throughout its length (Fig M 11.14). In the saguaro cactus (Carnegiea), the cauline bundles rarely or never merge. The saguaro is a eudicot. The other basic pattern is a reticulum of cauline bundles that are connected at various places to other cauline bundles along their lengths. Each bundle fuses with other bundles at some point along its length, and each bundle can branch at various points to produce more cauline bundles, supply bundles to the leaves (leaf traces), or bundles to branches (branch traces) (Figs M 11.15, 16)

monocots; conjunctive; independent;

Stems that undergo more or less continued growth from a single apical meristem are termed _____ (palms; conifers), while those stems that grow for only a predetermined amount of time and then abort are referred to as ______ (many species of deciduous trees). In sympodial stems, a few leaves, axillary buds, or other structures are produced and then the apical meristem _____ growing. New growth is resumed from an apical meristem in one of the ____ buds or stems. Some plants produce two different types of stems simultaneously. In many plants, the branches differ from the main stem in their anatomy and the types of leaves they produce. These lateral stems may have extremely short internodes, and the plant consists of long shoots and short shoots. Cacti and conifers are examples of plants with this type of stem pattern.

monopodial; sympodial; stops; lateral;

Most of the pulvinus is comprised of large, thin- and elastic-walled parenchyma cells that surround a core of vascular tissue. Numerous intercellular spaces are also present. Ten to twenty layers of parenchyma cells in the cortex surround the core of vascular tissue. Sometimes these parenchyma cells are known as _____ cells. Pulvinal movement is associated with changes in ____, and the concomitant contraction and expansion of the parenchyma cells on opposite sides of the pulvinus. Loss of turgor pressure in these parenchyma cells causes the petiole, petiolule, or pinna to ______ or fold (Fig).

motor; turgor; droop

Resin ducts may be present in both the axial and radial systems. Usually, only a narrow band of phloem is functional and conducting; the remainder is ______. If fibers are absent, the sieve cells and albuminous cells _____, the rays follow the collapsed pattern, and the tissue appears wavy (Pinus) (Fig E 14.3). The parenchyma cells are _____ in the non-conducting phloem and remain alive until they are cut off from water by sequent periderms. The parenchyma cells in the rays also remain alive.

nonfunctional; collapse; enlarged

Sclereids or fiber-sclereids may be present, but often only differentiate and become present in ______ phloem (Prunus, plum; cherry). Sclereids can be either ________, those that differentiate and mature at the same time as the other phloem cells, or ________, which arise only later after conduction ceases. Like sclereids, fibers also may develop later. Older parenchymatous portions may later become sc lerenchymatous. Septate fibers are sometimes present and function in ______ (Vitis).

nonfunctional; primary sclereids; secondary sclereids; storage

At least in plants that have a deciduous habit, the vessels are ____ continuous from stem to leaf. If they were, when the leaf was lost, the resulting ____ that would form from the exposed vessel elements would move into the metaxylem and cause it to cease functioning. Bridging between the vessels in the stem and those in the leaf is accomplished by: 1. a set of bridging or _____ tracheids. 2. a constricted zone of vary narrow vessels. The vessels in this zone may not be continuous, but instead _____. In either case, by the water moving only through pits/pit-pairs, embolisms cannot reach the conducting elements of the cauline metaxylem. Plants that have only tracheids do ___ have constricted zones. At least some of the parenchyma in the nodal region is modified into ___ cells; this is probably to facilitate transport of substances between the axial and lateral systems. Some of the parenchyma cells in the node have thick cell walls and numerous plasmodesmatal connections

not; embolism; intervening; overlap; not; transfer

There are three states of the endodermis: 1. state one (primary state): endodermal cells have ____ casparian strips; found in young, actively absorbing roots. 2. state two (secondary state): suberin is deposited over all of the primary walls except where _____ occur. 3. state three (tertiary state): a variably thickened layer of _____ is deposited between the suberin lamella and the plasmalemma, and lignification also occurs. Types two and three occur in the endodermal cells of older roots. Types two and three minimize the ability for solutes, and subsequently water, to diffuse out of the vascular cylinder. The deposition of suberin, cellulose, and lignin does not happen to all of the cells at the same time, or even to all of the cells. Cells that remain in the type one state are referred to as _____ cells

only; plasmodesmata; cellulose; passage

The primary thickening meristem is located between the ____ cortex and the central, highly vascularized region. At least some of the monocotyledonous species that produce bulbs and rhizomes increase the ____ in these organs in part through the primary thickening meristem. In some monocots, the rhizome undergoes secondary growth through a ______ thickening meristem.

outer; thickness; secondary

2. Unequal activity of the vascular cambium In some species, the vascular cambium does not remain uniformly active. Instead, certain regions produce tissues that are quite different from the tissues produced by other regions of the cambium (Aristolochia, Passiflora, and Ambrosia dumosa). There are two variations of unequal cambial activity: Variation one (Aristolochia): certain regions of the cambium produce _______ tissue. Parenchyma is produced to both sides of the cambium and this continues indefinitely. The other regions that are producing normal conducting tissues can also begin producing parenchyma.

parenchyma;

In the sweet potato (Ipomoea batatus) (Convolvulaceae), Xylem tissue is produced in the common fashion, but it contains large amounts of _____. Cambia arise around individual ____ or groups of vessel elements, or occasionally around clusters of parenchyma cells. These cambia produce a few tracheary elements to the inside and some phloem to the outside, but mostly parenchyma on both sides (Fig R 24.22). A vascular cambium in the normal position separates the common type xylem from the common type phloem. In certain members of the Brassicaceae family, including the radish (Raphanus sativa) and the turnip (Brassica rapa), parenchyma of the xylem and pith proliferates producing cambia in these tissues, which in turn produce vascular tissues. In all of these examples of anomalous secondary thickening in roots, a common theme occurs, which is cambia and vascular tissues embedded in a sea of ______.

parenchyma; vessels; parenchyma

Anomalous secondary thickening in eudicot storage roots In storage taproots of the carrot (Daucus carota) and parsnip (Pastinaca sativa) (Apiaceae), secondary thickening is of the common type, but the cambium produces mostly _____ wood. In the beet (Beta vulgaris) (Chenopodiaceae), a series of _____ cambia arranged concentrically around the outside of the normal vascular core are formed. The cells of these supernumerary cambia are produced from ______ The supernumerary cambia produce several increments of secondary tissues, each comprised of storage parenchyma and strands of xylem and phloem separated from one another by wide radial panels of parenchyma (Fig R 24.23).

parenchymatous; supernumerary; pericycle and phloem cells.;

Movement of substances into the vascular cylinder also occurs in roots that have a state two or state three endodermis. Water movement occurs through _____ cells and those cells that are suberized and or lignified. These cells remain alive and have numerous plasmodesmatal connections with parenchyma cells in the vascular cylinder. Exodermis The exodermis is essentially an endoermis that is located on the periphery of the cortex, as a hypodermis. The hypodermis, if present, is the layer(s) of cells immediately below the epidermis, if it is distinct from all other cells above and below it. Otherwise, it is not recognized as a hypodermis. The exodermis can be from one (usual case) to several cells thick. _____ casparian strips form initially in cells of the exodermis (at least in some species), followed by a thin suberin lamella, which is deposited over the inner surface of the cell walls. An additional layer of cellulose may be deposited and cells can become lignified.

passage; Thin

Lateral root primordia arise from groups of cells in the _____. When the lateral root primordia begin to grow, the pericycle cells divide mitotically in all directions, and the primordium begins to protrude into the cortex. The endodermis usually produces a one layered sheath of cells around the growing root primordium, but this endodermal cell sheath is short-lived. These endodermal cells may give rise to the _____ in some species, or in others, the rootcap and epidermis (Figs R 24.17; M 13.15, 16). A well-defined apical meristem is produced before the root emerges from the cortex. Often a rootcap is also present at this point. The emergence of the lateral root causes considerable damage to the cortex and epidermis of the parent axial root. Usually a specialized corky tissue is produced to seal the exposed tissues.

pericycle; rootcap;

In palms, the vascular bundles are concentrated toward the ____ of the stem and they have numerous fiber-tracheids. Sclerenchymatous bands of fibers also may be present. Thus, the palm stem is flexible, but still very strong. The bases of palms often become very thick because of adventitious roots that are produced and grow downward through the stem tissues, pushing some of the tissues of the ______ (stem) outward.

periphery; caudex

5. _____ (comprise the corolla) are also modified leaves that are involved with attracting pollinators. Sepals and petals are only found in the phylum _____ (angiosperms), and together comprise the perianth. 6. seed leaves or _____: store nutrients for the embryo. Cotyledons can also have a photosynthetic function. Cotyledons allow the embryo time to establish (photosynthetic) self-sufficiency after germination. 7. ______ and microsporophylls: function in reproduction. In the angiosperms, the megasporophylls are the ____ and the microsporophylls are the ____. These seven types of leaves are present in the seed plants. Gymnosperms have leaves in their cones that are similar to hypsophylls and sepals in function.

petals; Anthophyta; cotyledons; megasporophylls; carpels; stamens;

The leaflets of compound leaves can have an obvious petiole like structure known as a _____, or they can be sessile. Compound leaves can be ______ compound, where the leaflets all originate from a central point at the apex of the petiole, or _____ compound, where the leaflets or pinnae arise from numerous points along a central rachis. Compound leaves can be compounded one or more times. Leaves that are more than one time compound are often referred to as ______ (Fig). The _____ is the central stalk of the lamina to which the leaflets or pinnae are attached (the midrib or midvein of a pinnately compound leaf). If a leaf is only one time compound, than only the rachis and its leaflets comprise the lamina. If a leaf is two or more times compound, ____ (si. pinna) are present. Pinnae are _____ that originate from the rachis, and usually bear additional leaflets. If the leaf is decompound, additional pinnae known as pinnules will sometimes be present. The pinnules are attached to the pinnae. The stalk of a pinna is sometimes referred to as a ____ (Fig).

petiolule; palmately; pinnately; decompound; rachis; pinnae; stalks; rachilla

Within the patch, included parenchyma cells become mitotically active and differentiate into _____ cells. Occasionally, a cambium can form in the parenchyma tissue, but it produces only more parenchyma cells. In Azima tetracantha, there is a phloem connection between the patches of included phloem and the external phloem. The central regions of the multiseriate xylem rays differentiate into phloem (sieve tube members and companion cells). This species has ____ oriented phloem bundles that run through the xylem ray parenchyma. This phenomenon may occur in other species (Fig M 18.9).

phloem; horizontally

5. Discontinuous, unidirectional cambia In some Bignoniaceae, a normal cambium forms producing secondary tissues. Subsequently, four small regions of cambium located opposite of each other become unidirectional and produce only ____. Because these regions produce no xylem, they remain stationary in the plant. The other regions of the cambium continue to produce secondary xylem to the inside (continue as bidirectional meristems) and the cambium moves outward. The secondary phloem being produced by the unidirectional vascular cambium must slide past the xylem on its sides. After some time, other portions of the bidirectional cambium ____ to unidirectional tissue production, repeating the process (Figs M 18.10, 11).

phloem; revert

The collective term for all of the leaves of a plant is the _____. Essentially, all ferns and seed plants possess leaves, although sometimes they are very small. Leaves function in the following ways: 1. photosynthesis. 2. protection (spines, glands, etc.). 3. reproduction and attraction of pollinators. Leaves are involved with both sexual and asexual reproduction. 4. climbing and attachment to the substrate by various types of vines (tendrils). 5. storage (the leaves of bulbs and some succulents). 6. buoyancy (some aquatic plants). 7. predation (carnivorous plants). 8. nutrient absorption. 9. gas exchange between the plant and the external atmosphere. 10. movement of water and nutrients through the plant body. 11. symbiotic relationships with other organisms. Some species of Acacia produce food for ant symbionts from their leaves. The structures, known as ______ bodies, are comprised of proteins and oils.

phyllome; beltian

The arrangement of leaves on the stem is known as ______ or phyllotaxis. Three main arrangements are possible. The number of axillary buds typically ______ the number of leaves (Fig). 1. _____: one leaf per node. A. ______ or two-ranked; one leaf at each node, but disposed in opposite ranks. B. helical: gives rise to a spiral arrangement of the leaves along the stem. 2. opposite: two leaves per node. A. distichous: leaves in two ranks with successive pairs at the same angle. B. _________: leaves in four ranks with successive pairs at right angles. 3. verticillate or whorled: three or more leaves per node. In addition to leaves and axillary buds, adventitious roots can also be present at a node (or internode).

phyllotaxy; equals; alternate; distichous; decussate

The pith can be an important area of storage. Usually the pith is fairly small, so its role in storage is minor. However, in the tuber of the potato [Solanum tuberosum (Solanaceae)], almost the entire volume of the tuber is ____. During development in many species, the cells of the pith mature ____ than the surrounding tissues. Because of this, the pith is often ____ apart as the surrounding tissues continue to grow and elongate. The tearing may be irregular, or individual layers may separate from adjacent layers forming ____ (si. septum), which divide the hollow pith into compartments—producing a chambered or ____ pith. The pith, if present, is actually part of the vascular cylinde

pith; earlier; torn; septa; lamellate

Leaves Leaves are the most _____ plant organs from an evolutionary standpoint; more so than roots or stems. Numerous types have evolved in response to environmental selection pressures. There are seven main categories of leaves. 1. foliage leaves or _____: function in photosynthesis and gas exchange. 2. bud scales or _____: protect developing vegetative buds. 3. floral bracts or _____: protect developing inflorescences or individual flowers. 4. _____: (comprise the calyx) protect individual flowers. Sometimes also involved with attracting pollinators.

plastic; tropophylls; cataphylls; hypsophylls; sepals

Subapical meristems also exist in leaves, and they are referred to as _____ meristems, and consist essentially of the entire lamina. When the lamina is young, all portions of it undergo growth in length and width, but additional cell layers are not added to the individual layers of the leaf. The individual layers of the lamina are initiated at the margins, but are then expanded by the plate meristems. In leaves that are lobed, certain areas of the marginal meristems have high rates of cell division. These areas produce the ____, while other areas have low rates of cell division—resulting in ______ (spaces between the lobes). In compound leaves, marginal meristems do ____ develop. Instead, two rows of projections are formed. These projections are leaflet _____. As the leaflet primordia become larger, they will form marginal meristems if the leaf is ____ time compound, or more leaflet primordia if the leaf is two or more times compound.

plate; lobes; sinuses; not; primordia; one

Between the endodermis and the epidermis is a compact, chlorenchymatous mesophyll. In some conifers, the mesophyll is comprised of lobed (______) parenchyma cells. In others, a palisade and spongy mesophyll are present. Resin canals are present in the leaves of conifers. Sometimes only epithelial cells line the canal, whereas others also have a lignified sheath. Leaves of conifers can be scales or needles. The scale leaves may contain numerous vascular bundles, but the needle leaves have only ____ or two.

plicate; one

In monocot roots, the xylem is usually _____. Some anatomists consider the root of monocots to be a _____, where the central tracheary elements or xylary elements have converted to parenchyma, forming a pith. The roots of some palms (Arecaceae) and screw pines (Pandanaceae) can have up to 100 protoxylem poles. These species do not have the capability to undergo secondary growth to produce more conducting tissues in order to keep pace with an increasing shoot system. Therefore, they must produce excess vascular tissue at the beginning, which will support the larger shoot system later on. The phloem in the root occurs in bundles or clusters ____ to the xylem. The clusters of phloem are located between the protoxylem poles and are ____ in number to them. Usually the phloem is located exterior to the xylem, but sometimes it also occurs in the pith in those roots which have one (Cordyline, Dracena, Musa, and Pandanus). In some roots, the phloem and the xylem form collateral bundles.

polyarch; protostele; exterior; equal;

1. _____ stele: two or more concentric vascular cylinders (Pteridium) (Fig). The _____ vascular cylinder forms in the young plant, and the inner cylinder forms in the upper portions of the stem as the plant becomes larger. The two steles are connected together at the base of the inner stele. 2. ______: several steles run parallel to each other. In cross section, the steles may be organized into a ring, or they may be scattered. The individual steles can anastomose with each other to form a network. Polysteles can occur in ______. Vascular bundles A vascular bundle is any bundle that has vascular tissues in it. Vascular bundles are sometimes referred to as _____. Types of bundles based on their position in the stem. 1. _____ bundle: the steles of stems in all seed plants contain a set of vascular bundles (contain primary xylem and primary phloem) known as cauline bundles, stem bundles, or ______ bundles.

polycyclic; outer; polystele; stems or roots; fascicles; cauline; axial

Diffuse growth Palms (Arecaceae) do not truly undergo secondary growth. Initial stem thickening is via a _____ thickening meristem. Some species of palms then undergo an additional increase in stem diameter by means of diffuse secondary growth. In diffuse secondary growth, parenchyma cells in the stem proliferate—undergo cell division and enlarge, which gives an increase to the _____diameter of the stem. The cells that mostly are involved in the process are the outermost cells of the ______and those in the conjunctive tissues.

primary; diameter; bundle sheaths

Essentially, all stems in the ____ state of growth have an epidermis, cortex, and vascular cylinder or stele. The stele consists of some arrangement of______ (this can be variable), which contain the primary xylem and primary phloem and any associated ground tissues. In gymnosperms and eudicots, the vascular bundles are typically arranged in a ____ towards the periphery of the stele, whereas monocots usually have their vascular bundles scattered throughout the stele. Epidermis Stems generally have an epidermis. The stem epidermis of some aquatic plants lacks _____. Cortex The cortex is the region between the epidermis and the outermost cells of the vascular cylinder. It is comprised of one or more ground tissues. Parenchyma is always present in at least some amount. A collenchymatous or sclerenchymatous hypodermis is sometimes present. Sometimes a sclerenchymatous sheath occurs to the periphery of the vascular tissue (Cucurbita).

primary; vascular bundles; ring; stomata;

Stems are extremely variable. Stems function in the following ways. 1. production and support of leaves. 2. conduction of water, carbohydrates, and nutrients between the areas of photosynthesis, and the root system or storage organs. 3. storage of water and nutrients. 4. perennation and survival of the plant during adverse environmental conditions. 5. asexual reproduction and dispersal. Stems of certain species [(exs., Eichhornia (water hyacinth) (Pontederiaceae), Pistia (water lettuce) (Araceae), and Colocasia (elephant ear) (Araceae)] all break very easily into segments (disarticulate or fragment), which allows for easy asexual reproduction and subsequent dissemination (dispersal) of vegetative _____.

propagules

2. ______ layer: this layer is located just proximal to the abscission layer. The cells of this layer undergo cell division to form a ____ layer. These cells can force their way into ducts and canals to seal them off, and can generate tyloses into vessels. Once formed, these cells become suberized or filled with gum to seal of the exposed area. All cells to the periphery of the protective layer die. 98 Once the leaf has fallen, the protective layer is recognized as a leaf ____, and within the leaf scar, ____ scars (where the leaf traces entered the stem) also occur. Pulvini The _____ (si. pulvinus) are large, swollen portions at the base of the petiole. Pulvini may also occur at the apex of the petiole. In compound leaves, additional pulvini (secondary pulvini, tertiary pulvini, etc.) can occur at the base of the pinnae, and the petiolules of the leaflets (Fig R 28.26). Pulvini are very prominent in the leaves of plants in the pea family (Fabaceae).

protective; sealing; scar; bundle; pulvini

In some ferns, shoots may have both protostelic and siphonostelic character at different areas, depending on vigor and shoot size. The shoots of seed plants are never _____. The original protostele was probably a _____. Types of protosteles (Fig). 1. _____: xylem mass is circular in outline (Selaginella; Dicanopteris). 2. _____: xylem mass is undulate in outline (Psilotum; Lycopodium). The roots of most seed plants have this. Some monocots (Lilium, Triticum) have roots with polyarch actinosteles. 3. ____: xylem mass occurs as a series of plates and small cylinders (Lycopodium). Types of siphonosteles (Fig). Two subtypes: A. amphiphloic siphonostele: phloem occurs both to the inside and outside of the xylem (_____ only). 1. ______: the vascular tissue occurs as a complete circle or an almost complete circle (c-shaped) with a single leaf gap present. Leaves are not positioned close together on the stem (Adiantum).

protostelic; haplostele; haplostele; actinostele; plectostele; ferns; solenostele

The vasculature of the leaf begins as _____ tissue in the midvein, and development and differentiation proceeds outward from there. In Welwitschia, a gymnosperm, the leaves are kept for the entire life of the plant, and continue to grow and elongate each year. Monocots Monocot leaf development is different than that of eudicots. In grasses (Poaceae), leaf development also begins with a leaf primordium, but the regions of the shoot apex on either side of the primordium also become active as _____ tissue. The cells adjacent to these become primordial, and the entire process continues until the primordium appears to be seated on a short sheath that encircles the base of the apical meristem (Fig).

provascular; primordial;

Some monocots, such as palms (Arecaceae and some aroids, ex. elephant ears (Araceae), have complex leaves that somewhat resemble those of eudicots. These leaves even have a petiolelike portion known as a _____. These leaves are usually comprised of a lamina, a leaf base, and a pseudopetiole. The leaf will have a broad base where it attaches to the stem known as a _____. If the two margins of the sheath do not touch, the sheath is open. If they fuse, the sheath is closed. Many monocots have sheathing leaf bases. The leaf base may consist of a sheath only, or a small flap of tissue from the epidermis may be present at the point where the sheath attaches to the blade. This tissue is referred to as the _____.

pseudopetiole; sheath; ligule

Hydrophytic leaves Submersed aquatic plants are known as hydrophytes, and the leaves of these plants have undergone major changes in structure because they occur under water. Hydrophytic leaves typically have one or more of the following characteristics: 1. thin and 1____ cuticle. 2. _____ (water stomates) are commonly present. 3. water movement in the xylem occurs by ____ pressure. 4. sometimes the xylem tissue is not well developed. 5. presence of gas chambers (air chambers) to allow for buoyancy because cellulose and protoplasm is slightly denser than water. The gas chambers are filled with gasses generated by the plant. Gas chambers occur in leaves, but can also occur in the stems and roots.

reduced; hydathodes; root;

If the phellogen produces phelloderm to the inside, the phelloderm can be difficult to distinguish from the cells of the pericycle. Sequential periderms may develop deeper in the root, and if so, the root will form a ______. Summary of

rhytidome;

Some plants lack stems and the main plant body is comprised of a photosynthetic _____ system. Flower buds are produced adventitiously from the roots, or from only a small residual portion of shoot. In others, the entire plant body consists of stems (Psilotum, whisk fern; Tillandsia usneoides, Spanish moss), where the stems carry out the functions of leaves and roots, as well as those typical for stems. Some endoparasitic eudicots completely lack roots, stems, and leaves altogether. The plant body consists of an endophytic, mycelium-like mass of _____ embedded within their host's body. Only during reproduction is a short portion of "____" stem tissue produced, which bears the flowers and fruits.

root; filaments; normal

All gymnosperms, most eudicots, and a few monocots undergo secondary growth in their _____. The vascular cambium arises from: 1. the ______ cells that remain between the primary phloem and primary xylem. In roots that do not undergo secondary growth, these cells differentiate into parenchyma or sclerenchyma. 2. from portions of the _____. Initiation of the vascular cambium begins at the strips of procambial cells between the primary vascular tissues (here, the vascular cambium initially occurs as strips that are _____ in number to the number of protoxylem poles). Subsequently, the pericycle cells to the periphery of the xylem become meristematic. The two areas of cells become united and the vascular cambium is formed. At this point, the vascular cambium has the outline of the xylem tissue (Fig).

roots; procambial; pericycle; equal;

The intercellular spaces of most leaves are formed _____. The spongy mesophyll cells stop growing and expanding _____ the palisade mesophyll cells. Therefore, they are torn apart sooner, and have larger intercellular spaces. The epidermis and cells of the veins continue to grow and tear the mesophyll cells apart. 95 The mesophyll cells that contain chloroplasts are sometimes referred to as _____. The mesophyll cells of grasses can be unlobed, slightly lobed, deeply lobed, or branched. Conifers can also have _____ mesophyll cells. These lobed mesophyll cells, in particular those found in gymnosperms, are sometimes referred to as _____ parenchyma.

schizogenously; before; chlorenchyma; lobed; plicate

To support the weight of large leaves, much _____ is usually present. Large leaves often also are ____ because the individual leaflets can flutter on the rachis allowing the wind to flow through the leaf, and reduce resistance. Compound leaves also dissipate heat ____ than a simple leaf with the same area. Heat dissipation from leaves Leaves exposed to full sunlight have a high heat load, even though only about ____% of the total solar energy striking the leaf is absorbed (most of which is energy in the visible portion of the spectrum). Heat is dissipated from leaves in three ways: 1. _____ heat loss: emission of long-wavelength radiation ((at about 10,000nm) 2. ____ heat loss: heat is convected from the leaf surface to the air (circulation of air around the leaf removes the heat from the leaf surface); works so long as the temperature of the leaf is higher than that of the surrounding air. 3. ____ heat loss: evaporative loss of heat because of water loss via transpiration.

sclerenchyma; compound; better; 50; radiative; sensitive; latent;

Transfusion tissue is also present in the conifers. Conifer leaves are stiff with a thickened cuticle, and are considered _____, The cells of the epidermis and hypodermis have thick walls. Conifer leaves are simple, and as do the leaves of cycads, have numerous xeromorphic characters. The leaves of many conifers undergo secondary growth. The cambium often produces a few cell layers of new secondary phloem each year, but little or no secondary xylem (Pinus, Taxus). The vascular tissues are surrounded by a sheath of transfusion tissue and then an endodermis. The transfusion tissue consists of living transfusion parenchyma and dead transfusion tracheids.

sclerophylls

Endodermis Almost all species investigated thus far have an endodermis in their roots. The roots of black gum (Nyssa sylvatica) (Nyssaceae) and a few other species lack an endodermis. The endodermis is comprised of a _____ layer of cells. The endodermis divides the root apoplast into two distinct compartments because of its casparian strips. The casparian strips or casparian bands are suberized and sometimes also _____ regions in the transverse and radial walls of some or all of the cells of the endodermis. These casparian strips separate the apoplast of the cortex from the apoplast of the vascular cylinder, causing a discontinuity between the two regions (Fig R 24.13). The suberin is incrusted into the cell walls. Water and other substances can move through the cortex via the apoplast or symplast, but can only enter the vascular tissues after passing through the _____ of the endodermal cells. Thus, the plant can be selective as to which ions enter the vascular tissues and which do not, and stop the leakage of ions out of the vascular cylinder back into the cortex.

single; lignified; symplast;

Foliage leaves Leaves can persist for only a _____ growing season, or can persist for two to several years (up to 33 years in the bristlecone pine). The leaf is comprised of two basic portions, the ____ or leafstalk and the blade or ____. If a leaf lacks an obvious petiole, it is termed ______. If a petiole is present, the leaf is said to be ____ (Fig). Leaves can be either simple or compound. In a simple leaf, the lamina or blade is ____, though the outline of the lamina may be variously lobed or dissected. Compound leaves have the lamina dissected into discrete segments known as ____ (occasionally, a leaflet is referred to as a pinna). Sometimes the ultimate leaflets of a leaf that is two or more times compound are referred to as ____ (Fig).

single; petiole; lamina; sessile; petiolate; continuous; leaflets; pinnules

Other areas produce much more phloem and thus the cambium is pushed outward more ______. These areas of unequal xylem production cause the wood to have a very uneven outline, with the vascular cambium following that outline. In Ambrosia, this anomalous growth causes ____ of the stem into several strands. This allows certain portions of the stem and crown to receive enough water to survive during periods when available water becomes scarce (water is channeled to the dominant branches which survive).

slowly; splitting

The phyllome of a plant is often comprised of more than one type of leaf. Leaves can be modified into spines, tendrils, glands, insect traps, floats, and storage organs. A ______ is a modified leaf or portion of a leaf that has a sharp apex (Fig). Phylogenetically, leaves can be classified into two main categories. Each one is evolutionarily distinct and unrelated. 1. _____: typical leaves and their modifications. These are more derived (advanced) evolutionarily than microphylls. Megaphylls originated as an entire ______ system. Found in most ferns and all seed plants—______ (Monilophyta and all seed plants). 2. _______: more ancient than megaphylls. Microphylls probably originated as small outgrowths of the stem known as _____. Only a few groups probably possess them, such as the Lycopodiales.

spine; megaphylls; branch; Euphyllophytes; microphylls; enations

At about this same level, each phloem strand bifurcates (____) resulting in four phloem strands. Higher still, the metaxylem elements differentiate on each side of the xylem clusters (differentiation does not occur on the side adjacent to the pith). The xylem is changing from exarch to endarch. Four groups of metaxylem are now present (Fig). Each metaxylem strand is near a metaphloem strand, forming true, endarch, collateral bundles. These four bundles then divide to produce a total of eight collateral bundles (Fig). The transition region is similar in gymnosperms, but slightly more complex because they have more cotyledons.

splits;

Sometimes the innermost portion of the cortex accumulates starch. This region, if present, is known as a _____. In some species, the cortex can have an ______ [Acorus (Acoraceae)]. Most stems do not have an endodermis, but it is encountered in rootlike stems, such as _____. Chlorenchyma is often present. Secretory tissues and idioblasts can also be present. The width of the cortex can range from very wide to very narrow. Pith The pith is almost always comprised of parenchyma tissue. Occasionally, chlorenchyma is present. Sclerenchyma can also be present (this is rare) [wax plant (Hoya sp.)], and can consist of either sclereids or fibers. Sometimes the fibers form a ring close to the vascular bundles (Cycadaceae). Sometimes the cells at the perimeter of the pith differ from the rest, and this area is known as the _____ zone. Sometimes the pith is referred to as the ____.

starch sheath; endodermis; rhizomes; perimedullary; medulla

Leaf anatomy of C4 plants C4 plants have kranz anatomy in their leaves. Kranz anatomy is the radial arrangement (the mesophyll cells form a ring) of chlorophyllous mesophyll cells around the large bundle sheath cells. The mesophyll is typically not divided up in palisade and spongy portions. The bundle sheath may consist of one layer of cells or two layers. If only a single layer of cells is present, these cells are usually large, thin-walled parenchyma cells. These cells often contain large amounts of _____. In this case, sometimes the bundle sheath is referred to as a ______. When the sheath consists of two cell layers, the outer sheath is as just described, and the inner sheath or _____ sheath is an endodermis. Some C3 grasses also have a two-layered bundle sheath [wheat (Triticum)].

starch; starch sheath; mestome;

At the base of the leaf where it attaches to the stem, a pair of stipules are often present. The ____ may receive vascular traces from the leaf traces, or may have their own independent traces. A stipule is an appendage that occurs at the base of attachment of the petiole. Stipules can be foliaceous (leaflike) or narrow, spinose, or small or large. Sometimes the stipules are _____ and encircle the stem. Not all plants have stipules. In many species of monocots with large sheathing leaf bases, each leaf receives numerous traces that arise from many cauline bundles.

stipules; sheathing;

Epidermis The epidermis of leaves is similar to that of other organs, but numerous _____ are usually present. Because the leaf is dorsiventral, the epidermis on the upper or ____ surface is in a different environment than the epidermis on the lower or abaxial surface. The two epidermises have somewhat different ____. The adaxial surface typically has few stomata, or occasionally none. An exception to this are species of aquatic plants that have leaves that float on the surface of the water. The stomata are all on the adaxial surface of the leaves in these plants. The abaxial surface typically has numerous stomata, and often has trichomes or stomatal crypts to minimize water loss from the leaf.

stomata; adaxial; functions;

Nonfunctional phloem is important in ________. Often the functional (conducting) phloem is confined to a ________ (current year's growth). Many times the sieve tube members cease to function at the end of the growing season and die. In some species (Vitis; Liriodendron), the sieve tube members go ______ in the fall, but resume conduction the following spring, or function even more than two years (Tilia). In species with included phloem (discussed later), the phloem may function for many years.

storage and protection; single growth ring; dormant;

Monocot leaves Numerous monocots have elongate, _____-shaped leaves that grow from a basal meristem. Therefore, the oldest portion of a leaf is towards the ____. The majority of the vascular bundles run parallel to the long axis of the leaf, giving rise to the parallel _____ pattern typical of most monocot leaves. Large veins often alternate with smaller ones. A prominent midrib may or may not be present. The larger veins are interconnected by small veins known as _____ bundles. 99 The sclerenchymatous bundle sheath extensions of monocots are important for support, especially because the leaves tend to be elongate. Some monocots, such as bananas (Musa) and cannas (Canna), have ______ venation. Here, the leaf has a prominent central midvein with numerous smaller secondary veins branching from it that run perpendicular to the long axis of the leaf and parallel to each other. A few monocots, such as greenbrier, sawbrier (Smilax), have leaves with net venation or reticulate venation. In leaves with reticulate venation, the veins form a netlike or anastomosing pattern. Reticulate venation is also the typical venation pattern found in ____ leaves (Fig)

strap; apex; venation; commisural; peniparallel; eudicot

Important terms: 1. primary thickening meristem: a broad meristematic region in the _____ region of most species of monocots and in certain species with extremely thickened stems. This meristem occurs as a zone of mitotic activity that encompasses at least a portion of the ______ or conjunctive tissue, the provascular tissue, and the cortex. This meristem occurs in _____ (are gymnosperms), many monocots, and some eudicots with short, wide stems. The primary thickening meristem is considered a ____ meristem. This meristem produces primary vascular bundles embedded in ground tissues. In addition, it functions in the production of adventitious ____, primary stem thickening, and formations of linkages between stem, root, and leaf vasculature.

subapical; pith; cycads; lateral; roots

The patterns of branching or anastomosis are highly variable with numerous configurations; many can be quite complex. Each cauline or axial bundle and its series of leaf traces are termed a _____. If the sympodia are relatively distinct (not connected directly to other sympodia), then the plant has a stele that is said to be _____. Plants that have a truly reticulate system of sympodia that are connected by bundles as large as the cauline bundles have a stele that is closed (Fig). In a closed stele, damage to a single cauline bundle will not result in the death of the tissues supplied primarily by that bundle because of the highly interconnected network of vasculature that occurs with a closed stele.

sympodium; open;

In plants that have wide interfascicular regions, the interfascicular cambium often starts at the positions nearest to the fascicular cambium and then proceeds _____ (toward the center of the region). Once these two cambia have formed and become ____, the vascular cambium is formed, and secondary tissues are produced (Fig). The primary phloem fibers, if present, remain identifiable for some time after secondary growth has begun. 90 Vascular cambium formation is not uniform around the circumference of the stem. Vascular bundles at a given level in the stem are in different stages of development. Thus, some of the bundles enter secondary growth sooner than others. The vascular cambium of the main stem(s) is _____ with the vascular cambium in the roots and smaller stem branches. The vascular cambium of older portions of the plant is continuous with that of younger portions. The secondary tissues are also connected with the primary tissues.

tangentially; united; continuous;

Sun and shade leaves The size and thickness of a leaf is affected depending on whether or not it develops in sun or shade. In many species, the sun leaves (those leaves exposed to large amounts of direct sunlight) are smaller and _____ than the shade leaves (those that develop under lower light intensities) of that same plant. The increased thickness of sun leaves is primarily because of a greater development of the palisade parenchyma. The vascular system of sun leaves is more _____ than that of shade leaves. The walls of the epidermal cells are also thicker in sun leaves. Because light intensities vary in different places of the canopy, extreme forms of sun and shade leaves can occur.

thicker; developed;

Remember that endarch, mesarch, and centrarch xylem development occur in stems. The protoxylem forms as a series of rods on the periphery of the xylem cylinder. The most common number of rods or protoxylem poles is ____ (triarch) or four (tetrarch). Roots with one protoxylem pole are termed monarch, those with two protoxylem poles (diarch), those with five protoxylem poles (pentarch), and those with multiple protoxylem poles (polyarch) (sometimes as few as five protoxylem poles is also considered polyarch) (Fig). Different roots of the same plant can have different numbers of protoxylem poles.

three;

Some vascular bundles have only phloem tissue surrounded by fibers. Others have the conducting tissues capped by a section or cluster of phloem fibers (fibrous cap) (Figs M 11.28, 29). 2. fiber bundles can occur, commonly in the leathery leaves of monocots (Yucca), and are groupings of fibers that resemble a vascular bundle. Fiber bundles are not vascular bundles, as there is no vascular tissue present. In some species, ex. some Cactaceae, the stem can have _____ sets of vascular tissues: 1. cortical bundles, 2. cauline bundles, and 3. medullary bundles, and all three sets can be interconnected. The vasculature of the cortical and medullary bundles can be connected to that of the cauline bundles, and the vasculature of the medullary bundles can pass through the parenchyma between the cauline bundles and connect directly with the cortical bundles.

three;

In some species, the leaf traces branch off from the cauline bundle and run horizontally into the leaf. In others, the leaf trace separates early on from the cauline bundle and extends upward for several nodes before entering into the leaf. Much of this distance is spent in the cortex. Eudicots typically have _____ leaf traces that enter into each leaf, one ______ trace and two lateral traces (Fig). The median trace often arises _____ in the stem than the lateral traces. Once the leaf traces have separated from the cauline bundles, they may fuse with each other, or split into additional traces (this is especially common with the lateral traces). The extra traces usually enter the same leaf. In species that have closely spaced verticillate leaves, each split enters a different leaf.

three; median; lower;

Isolated regions of the conjunctive parenchyma resume mitotic activity and form rosettes of cells that differentiate into fibrovascular bundles. The outermost cells in the rosette differentiate into fibers. The inner cells of the rosette develop into xylem (____ only) and phloem. These vascular bundles are known as _____ bundles or secondary vascular bundles. Stem structure of woody monocots (Fig). Extensive connections occur between the secondary vascular bundles and the primary vascular bundles at the center of the stem. Monocot roots almost _____ undergo secondary growth. A rare exception to this is the _____ (Dracena). As mentioned previously, woody monocots form a periderm similar to that found in eudicots or a periderm of storied cork.

tracheids; secondary; never; dragon's blood tree

There is no _____ region between stems and roots in the secondary plant body as there is in the primary plant body. The initial periderm forms from the epidermis or the cortex, or occasionally from the primary phloem. A rhytidome is also often produced.

transition

The area of transition between the stem and root is known as the _____ region. The arrangements of the tissues in the transition region are complex. Vascular transition occurs between the root and stem, and thus continuous strands of xylem and phloem are produced between the root and the stem. In a seedling of Linum (flax) (Linaceae), the root is _____; two strands of phloem alternate with the two protoxylem poles. As the transition occurs between root and stem, the vascular cylinder begins to ____ as a pith appears in the center. At lower levels of the transition region, the pith is comprised of only a few parenchyma cells, but at higher levels, enough parenchyma is present to push the xylem apart into two exarch bundles. There are now also two metaxylem groups (Fig).

transition; diarch; swell;

Structure of the root primary body Adventitious buds can form anywhere on the root. These buds can then grow and give rise to new shoots (stems). Epidermis The nature of the root epidermis varies with the age of the root portion on which it occurs. In the region of maturation, some of the epidermal cells undergo an asymmetric division to produce a large ordinary epidermal cell and a small cell, the root hair initial or ______. The trichoblast will form the root ____. A cuticle of cutin or suberin can cover the epidermis in roots. More root hairs are typically produced if the soil is ___ or the air has high moisture content. Root hairs tend to be longer in dry soil. Often aerial roots are devoid of root hairs until they reach the soil. The presence of root hairs on the roots of aquatic plants is variable; they can be present or absent, depending on species. Most root hairs are unicellular and short lived (one to three days)

trichoblast; hair; dry;

Leaf development Eudicots Leaf primordia are initiated by cells from both the ______ of the apical meristem. These meristematic cells that will initially give rise to the cells of the leaf are known as ____ cells. An apical meristem in the leaf occurs in the ferns. It may be present in the leaves of seed plants, but evidence for it is lacking. The majority of leaf growth in length occurs by cell division throughout the young leaf ____. These divisions are fairly localized and constitute an _______or ventral meristem (Fig). 103 Two longitudinal ridges begin to protrude from the two sides of the primordium. These are the ______ meristems, and will develop into the lamina. The marginal meristems are composed of two types of initials: marginal initials (equivalent to a _____) and submarginal initials (equivalent to a _____ or ground meristem).

tunica and the corpus; founder; primordium; adaxial meristem ; marginal; protoderm; corpus

The sclerenchyma of the veins and bundle sheath extensions functions possibly in: 1. support, though this may be minimal. Much of the rigidity of the leaf is caused by _____ pressure. 2. protection of the vascular tissues from insects. Petioles The petiole, if present, allows for/to: 1. position the leaves further from the stem so that they are less likely to ____ and shade one another. 2. the leaf to more freely in the wind. 3. leaf movement via _____. 4. leaf abscission. The petiole has a complex system of vasculature, and ground tissues (parenchyma, collenchyma, and or sclerenchyma) are present. Laticifers, resin ducts, and other secretory structures may be present. Occasionally, an endodermis is present.

turgor; overlap; pulvini;

All primary roots, with the exception of haustorial ones, have the same basic internal structure: epidermis, cortex, endodermis, pericycle, and vascular tissues. However, internal arrangement and the arrangement of the root system as a whole can be extremely ____. There are numerous types of roots and root systems. 1. _____ roots: roots present on the embryo in the seed prior to germination. 2. _____ or primary root: major or primary root in many species of gymnosperms and eudicotyledons. 3. ______ roots or secondary roots: secondary roots that branch out from the taproot or some other larger root. 72 4. _____ roots: lateral roots from the radicle (embryonic root) and adventitious roots formed from the crown (common root system type in grasses and many other monocots).

variable; seminal; taproot; lateral; fibrous;

In gymnosperms and eudicots that undergo secondary growth, the pericycle gives rise to the _____ (in part) and the ___ cambium (usually). Lateral ____ also originate from the pericycle. In monocot roots, the cells of the pericycle often become lignified as ____. Vascular tissues At the center of the root is the xylem tissue (gymnosperms, eudicots and some monocots), or a parenchymatous pith (some monocots). The xylem consists of protoxylem and metaxylem. In gymnosperms and eudicots, the metaxylem is in the very _____ of the vascular cylinder, surrounded by the protoxylem. The large vessel elements or tracheids in the center are metaxylem tracheary elements. It is essentially impossible to draw a distinction between where the protoxylem ends and the metaxylem begins. The development of the primary xylem in roots is ______ (development from the outside in, toward the center; the protoxylem occurs towards the outside and metaxylem towards the center). Thus, roots in the _____ state of growth have exarch xylem. The first formed cells are the protoxylem tracheary elements. The metaxylem tracheary elements form and mature somewhat later. Development of the primary phloem in the root is also exarch (Fig).

vascular cambium; cork; roots; sclereids; center; exarch or centripetal; primary

Vascular cylinder or stele In stems, the vascular cylinder or stele begins with the ______ and may or may not contain a pith of ground tissue. In roots the stele begins with the _____. Development of the stele The patterns of xylem and phloem in the vascular cylinder (stele) comprise two basic types. 1. ______: the xylem forms a solid mass of tissue at the center that is surrounded by the phloem. No pith is present. Stems of some ferns and the roots of many seed plants. 2. _____: the xylem tissue is still toward the center, but a parenchymatous pith is present. Some ferns and the seed plants. The protostele is more ____ than the siphonostele. It is believed to be the vascular tissue pattern that occurred in the stele of the first vascular plant. The roots of nearly all plants have a _____. It is also the dominant pattern found in the shoots of many ferns. The siphonostele often occurs in the shoots of ferns and always in the _____ of seed plants, and the roots of some monocots. Siphonosteles probably arose twice, once in the ferns, and once in the Progymnospermophyta-seed plant line that gave rise to the seed plants.

vascular tissues; pericycle; protostele; siphonostele; ancient; protostele; stems;

8. sclerenchymatous bundle sheaths. 9. water storage cells are often present. These may be large mucilage cells (Cactaceae), regions of thin-walled, colorless parenchyma cells (Chenopodiaceae), or tracheoid idioblasts, which are short tracheidlike cells which occur dispersed in the mesophyll. The tracheoid idioblasts may hold ____ by it hydrogen bonding to their cell walls. In some grasses and other monocots, bulliform cells (also known as ______ cells) and hinge cells are involved with leaf involution or leaf _____. Leaf folding is probably an adaptation to reducing water loss from the leaf. Some grasses have naturally involuted leaves. ______ cells are colorless mesophyll cells with thin walls that function in involution. Bulliform cells may or may not be involved with expansion or contraction of the lamina, but they do store water and often times accumulate silica. Plants that occur in high saline environments are referred to as _______, and often have xerophytic characteristics.

water; expansion; folding; Hinge; halophytes

Yet another example of included phloem occurs in Azima tetracantha, Phytolacca, Salvadora, and Thunbergia. In these taxa, a normal vascular cambium arises initially, and produces secondary xylem and small amounts of secondary phloem. After some time, the outline of the xylem becomes _____ because certain regions of the cambium begin to produce mostly parenchyma to the inside, while others continue producing xylem. These patches of parenchyma are known as _____ tissue (conjunctive tissue can also refer to the matrix of pithlike tissue that surrounds the vascular bundles in a monocot stem or tracheary elements and phloem in a monocot root). These parenchyma patches remain small because the cambium soon _____ back to producing normal secondary xylem. The patch of parenchyma has now become included and is surrounded by xylem (included parenchyma??).

wavy, conjuntive, reverts