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.