Chapter 1: Tree Biology Flashcards
meristems
undifferentiated tissue in which active cell division takes place. Found in the root tips, buds, cambium, cork cambium, and latent buds.
differentiation
process in the development of cells in which they become specialized for various functions. Following division, cells change their structure assume a variety of special functions.
5 organs of plants
leaves, stems, roots, flowers, and fruit
primary meristems
produce the cells that result in elongation of shoots and roots
secondary meristems
lateral meristems; produce cells that result in increases in diameter
primary growth
root and stem growth in length. Occurs at the apical meristems and lateral meristems of all vascular plants
secondary growth
increase in root and stem girth or diameter. Occurs at lateral meristems in some vascular plants such as dicots
apical bud
bud at the tip of a twig or shoot
bud
small lateral or terminal protuberance on the stem of a plant that may develop into a flower or shoot. Undeveloped flower or shoot containing a meristematic growing point.
root cap
protects the apical meristem in roots
cambium
thin layer(s) of meristematic cells that give rise to the vascular system of the tree. Outward - to the phloem; Inward - to the xylem, increasing stem and root diameter
2 kinds of tissues that the cambium produces
xylem and phloem
xylem
main water-conducting 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. Wood of the tree.
phloem
plant vascular tissue that transports photosynthates and growth regulators. Situated on the inside of the bark, just outside the cambium. (Bidirectional, transports up and down.) Slow movement of carbohydrates (sugars) along pressure gradients, which require energy.
cork cambium
meristematic tissue from which the corky, protective outer layer of bark is formed
periderm
the outer layers of tissue of woody roots and stems, consisting of the cork cambium and the tissues produced by it, such as bark.
cellulose
structural component of the cell wall; complex carbohydrate found in the cellular walls of the majority of plants and algae and certain fungi.
most common organic compound on Earth
cellulose
lignin
organic substance that impregnates certain cell walls to thicken and strengthen the cell to reduce susceptibility to decay and pest damage; provides strength and rigidity allowing trees to grow tall.
4 primary functions of the xylem
- ) conduction of water and dissolved minerals (elements)
- ) support of the weight of the tree
- ) storage of carbohydrate reserves
- ) defense against the spread of disease and decay
carbohydrate
compound, combining carbon, hydrogen, and oxygen, that is produced by plants as a result of photosynthesis. Sugars and starches. Chains of carbon, hydrogen, and oxygen molecules chemically bonded together.
symplasm
living tissue of the tree; entire mass of protoplasm of all the cells in a plant, interconnected by plasmodesmata. Symplast.
apoplasm
nonliving tissue of the tree; free spaces in plant tissue. Includes cell walls and intracellular spaces.
tracheids
elongated, dead cells with pointy ends and thickened walls that conduct water and provide mechanical support; elongated, tapering xylem cell adapted for the support and transport of water and elements.
parenchyma cells
living cells interspersed among other xylem cells; located in the outer layers of xylem; store carbohydrates, help defend against decay, and have a structural function across the grain; thin-walled, living cells essential in photosynthesis, radial transport, energy storage, and production of protective compounds.
components of the xylem in hardwood trees
tracheids, fibers, parenchyma cells, and vessels
vessels
primary conducting elements in hardwoods; stacks of dead, hollow cells that form long tubes of water-conducting elements; more efficient in water conduction than tracheids; end-to-end, tube-like, water-conducting cells in the xylem of angiosperms
ring porous
species that form wide vessels early in the growing season and narrower vessels later in the season; pattern of wood development in which the large-diameter vessels are concentrated in the earlywood.
Examples of ring porous species
Elm (Ulmus)
Oak (Quercus)
Ash (Fraxinus)
diffuse porous
species that produce vessels of uniform size throughout the growing season; pattern of wood development in which the vessels and vessel sizes are distributed evenly throughout the annual ring.
Examples of diffuse porous species
Maple (Acer)
Planetree (Platanus)
Poplar (Populus)
growth rings
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. Result of seasonal production of xylem by the cambium.
earlywood
cells produced early in the season
latewood
cells produced later in the season
sapwood
xylem that conducts water; outer wood that is active in longitudinal transport of water and minerals; contains many living parenchyma cells
heartwood
nonconducting tissue that contains no living cells and is sometimes darker in color than the sapwood; wood that is altered (inward) from sapwood and provides chemical defense against decay-causing organisms and continues to provide structural strength to the trunk; not all trees have it
sieve cells
long, slender phloem cell in gymnosperms
sieve tube elements
specialized phloem cells involved in photosynthate transport; exist only in angiosperms
companion cells
specialized cell in the angiosperm phloem derived from the same parent cell as the closely associated, immediately adjacent sieve-tube member
components of functional phloem
living cells: sieve cells in conifers; sieve tube elements and companion cells in hardwoods
rays
parenchyma cells that extend radially across the xylem and phloem of a tree and function in transport, storage, structural strength, and defense; parenchyma cells that grow radially across the grain in small layers that extend across the growth increments of xylem and into the phloem; transport carbohydrates and other compounds into sapwood, store carbohydrates as starch, and assist in restricting decay in wood tissue.
bark
the outer covering of a tree’s branches, stems, and in some cases, roots
composition and purpose of bark
composed of protective tissues that moderate the temperature inside the stem, offer defense against injury, and reduce water loss
lenticle
small opening in the bark that permits the exchange of gases
twigs
small stems that provide support structure for leaves, flowers, and fruit
apical bud
bud at the tip of a twig or shoot; terminal bud
terminal bud
bud at the tip of a twig or shoot
lateral bud
vegetative bud on the side of a stem
axillary bud
bud in the axil of a leaf; lateral bud
dormant
in a period of dormancy
apical dominance
condition in which the terminal bud inhibits the growth and development of the lateral buds on the same stem/shoot formed during the same season
adventitious bud
bud arising from a place other than a leaf axil or shoot tip, usually as a result of hormonal triggers; produced along stems or roots where primary meristems are not normally found
epicormic
arising from a latent adventitious bud (growth point), usually in reference to a shoot; shoots that are produced from elongated dormant buds
node
slightly enlarged portion of the stem/twig where leaves and buds arise
internode
region of the stem between two successive nodes; area between nodes
autonomous
producing and storing enough carbohydrates to sustain itself