ISA Study Guide Chapter 1: Tree Biology

bud

(1) small lateral or terminal protuberance on the stem of a plant that may develope into a flower or shoot. (2) undeveloped flower or shoot containing a meristematic growing point.

plant growth regulator

compound effective in small quantities that affect the growth and/or development of plants. May be naturally produced (hormone) or synthetic.

carbohydrate

compound, combining carbon, hydrogen, and oxygen, that is produced by plants as a result of photosynthesis. Sugars and starches.

apical dominance

condition in which the terminal bud inhibits the growth and development of the lateral buds on the same stem formed during the same season.

root mat

dense network of roots near the base of a palm.

osmosis

diffusion of water through a semipermeable membrane from a region of higher water potential (lower salt concentration) to a region of lower water potential (higher salt concentration).

sinker root

downward-growing roots that provide anchorage and take up water and minerals. Especially useful during periods of drought.

tracheid

elongated, tapering xylem cell adapted for the support and transport of water and elements.

fiber

elongated, tapering, thick-walled cell that provides strength to wood.

vessel

end-to-end, tubelike, water-conducting cells in the xylem of angiosperms.

symplasm

entire mass of protoplasm of all the cells in a plant, interconnected by plasmodesmata. Symplast.

absorbing root

fine, fibrous roots that take up water and minerals. Most absorbing roots are within the top 12 inches (30cm) of soil.

apoplasm

free space in plant tissue. Includes cell walls and intracellular spaces.

photosynthate

general term for the sugars and other carbohydrates produced during photosynthesis

chlorophyll

green pigment of plants found in chloroplasts. Captures the energy of the sun and is essential in photosynthesis.

apical meristem

growing point at the tips of shoots and roots

dormant

in a period of dormancy.

source

in physiology, plant part that produces carbohydrates. Mature leaves are sources.

respiration

in plants, process by which carbohydrates and converted into energy by using oxygen.

secondary growth

increase in root and stem girth or diameter. Occurs at lateral meristem in some vascular plants such as dicots.

phototropism

influence of light on the direction of plant growth. Tendency of plants to grow toward light.

frond

large, divided leaf structures found in palms and ferns.

radial transport

lateral movement of substances, perpendicular to the longitudinal axis of the tree or stem.

sieve cell

long, slender phloem cell in gymnosperm.

xylem

main water- and mineral-conducting (unidirectional, up only) tissue in trees and other plants. Provides structural support. Arises (inward) from the cambium and becomes wood after lignifying.

cork cambium

meristematic tissue from which the corky, protective outer layer of bark is formed.

axial transport

movement of water, minerals, or photosynthates longitudinally within a tree.

reaction zone

natural boundary formed chemically within a tree to separate damaged wood from existing healthy wood. Important in the process of compartmentalization.

compartmentalization

natural defense process in tees by which chemical and physical boundaries are created that act to limit the spread of disease and decay organisms.

lignin

organic substance that impregnates certain cell walls to thicken and strengthen the cell to reduce susceptibility to decay and pest damage.

sapwood

outer wood (xylem) that is active in longitudinal transport of water and minerals.

guard cell

pair of specialized cells that regulate the opening and closing of a stomate due to a change in water pressure within cells.

ray

parenchyma tissues that extend radially across the xylem and phloem of a tree and function in transport, storage, structural strength, and defense.

ring porous

pattern of wood development in which the large-diameter vessels are concentrated in the early wood.

diffuse porous

pattern of wood development in which the vessels and vessel sizes are distributed evenly throughout the annual rings.

geotropism

plant growth produced as a response to the force of gravity, either positive, as in the direction of gravity (roots), or negative, as in opposite the direction of gravity (shoots).

cytokinin

plant hormone involved in cell division leaf expansion, and other physiological processes. Compounds with cytokinin-like activity may be synthetically produced.

auxin

plant hormone or substance that promotes or regulates the growth and development of plants. Produced at sites where cells are dividing, primarily in the shoot tips. Auxin-like compounds may be synthetically produced.

sink

plant part that uses or stores more energy than it produces.

phloem

plant vascular tissue that transports photosynthates and growth regulators. Situated on the inside of the bark, just outside the cambium. Is bidirectional (transports up and down).

monocot

plant with an embryo that has one seed leaf (cotyledon). Examples are grasses and palms.

angiosperm

plant with seed borne in an ovary. Consists of two large groups: monocotyledons (grasses, palms, and related plants) and dicotyledons (most woody trees, shrubs, herbaceous plants, and related plants).

gymnosperm

plants with exposed seeds, usually within cones.

leaf axil

point of attachment of a leaf petiole to a stem.

photosynthesis

process in green plants (and in algae and some bacteria) by which light energy is used to form glucose (chemical energy) from water and carbon dioxide.

differentiation

process in the development of cells in which they become specialized for various functions.

propagation

process of increasing plant numbers both sexually and asexually.

branch bark ridge

raised strip of bark at the top of a branch union, where the growth and expansion of the trunk or parent stem and adjoining branch the bark into a ridge.

anthocyanin

red or purple pigment responsible for those colors in some parts of trees and other plants.

root initiation zone

region at the base of a palm stem where lateral roots emerge.

temperate

region lying between the tropics and the poles that has relatively moderate temperatures.

internode

region of the stem between two successive nodes.

growth ring

rings of xylem that are visible in a cross section of the stem, branches, and roots of some trees. In temperate zones, the rings typically represent one year of growth and are sometimes referred to as annual rings.

primary growth

root and stem growth in length. Occurs at the apical meristems and lateral meristems of all vascular plants.

lateral root

root that arises by cell division in the pericycle of the parent root and then penetrates the cortex and epidermis.

buttress root

roots at the trunk base that help support the tree and equalize mechanical stress.

decurrent

rounded or spreading growth habit of the tree crown.

node

slightly enlarged portion of a stem where leaves and buds arise.

lenticel

small opening in the bark that permits the exchange of gasses.

stomata

small pores, between two guard cells on the undersides of leaves and other green plant parts, through which gases are exchanged and water loss is regulated.

companion cell

specialized cell in the angiosperm phloem derived from the same parent cell as the closely associated, immediately adjacent sieve-tube member.

chloroplast

specialized organelle found in some cells. Site of photosynthesis.

sieve tube element

specialized phloem cells involved in photosynthate transport. Exist only in angiosperms.

petiole

stalk or support axis of a leaf

ecology

study of the relationships among organisms and other living and nonliving elements of their environment.

antitranspirant

substance applied to the foliage of plants to reduce water loss (transpiration)

plant hormone

substance produced by a plant that, in low concentrations, affects physiological processes such as growth and development, often at a distance from the substance point of origin.

mycorrhizae

symbiotic association between certain fungi and the roots of a plant.

tropism

tendency of growth or variation of a plant in response to an external stimulus such as gravity (geotropism) or light (phototropism).

periderm

the outer layer of tissue of woody roots and stems, consisting of the cork cambium and the tissue produced by it, such as bark.

cambium

thin layer(s) of meristematic cells that give rise (outward) to the phloem and (inward) to the xylem, increasing stem and root diameter.

parenchyma cell

thin-walled, living cells essential in photosynthesis, radial transport, energy storage, and production of protective compounds.

excurrent

tree growth habit characterized by a central leader and a pyramidal crown.

evergreen

tree or other plant that does not shed all of its foliage annually.

deciduous

tree or other plant that sheds all of its leaves according to a genetically scheduled cycle as impacted by climate factors (usually during the cold season in temperate zones).

meristem

undifferentiated tissue in which active cell division takes place. Found in the root tips, buds, cambium, cork cambium, and latent buds.

lateral bud

vegetative bud on the side of a stem.

transpiration

water vapor loss through the stomata of leaves.

cuticle

waxy layer outside the epidermis of a leaf that reduces water loss and resists insect damage.

heartwood

wood that is altered (inward) from sapwood and provides chemical defense against decay-causing organisms and continues to provide structural strength to the trunk. Trees may or may not have heartwood.

carotenoid

yellow, orange, or red pigment responsible for those colors in some parts of trees and other plants.

cellulose

complex carbohydrate found in the cellular walls of the majority of plants and algae and certain fungi.

aerial root

aboveground roots. usually adventitious in nature and sometimes having unique adaptive functions.

CODIT

acronym for Compartmentalization Of Decay In Trees.

abscission zone

area at the base of the petiole where cellular breakdown leads to leaf and fruit drop.

branch collar

area where a branch joins another branch or trunk that is created by the overlapping vascular tissues from both the branch and the trunk. Typically enlarged at the bace of the branch.

root crown

area where the main roots join the plant stem, usually at or near ground level. Root collar.

epicormic

arising form a latent adventitious bud (growth point). Usually in reference to a shoot.

symbiosis

association of two different types of living organisms that often, but not always, beneficial to each.

included bark

bark that becomes embedded in a crotch (union) between branch and trunk or between codominant stems. Causes a weak structure.

adventitious bud

bud arising from a place other than a leaf axil or shoot tip, usually as a result of hormonal triggers.

apical bud

bud at the tip of a twig or shoot. Also known as terminal bud.

terminal bud

bud at the tip of a twig or shoot. Apical bud.

axillary bud

bud in the axil of a leaf. Lateral bud.

tap root

central, vertical root growing directly below the main stem or trunk that may or may not persist into plant maturity.

inflorescence

cluster of flowers.