Isa Chapter 1: Tree Biology

Front 1

meristem

Back 1

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

Front 2

differentiation

Back 2

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

Front 3

primary growth

Back 3

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

Front 4

Secondary growth

Back 4

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

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apical meristem

Back 5

growing point at the tips of shoots and roots.

Front 6

bud

Back 6

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

Front 7

cambium

Back 7

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

Front 8

xylem

Back 8

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. Contrast with phloem.

Front 9

phloem

Back 9

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

Front 10

cork cambium

Back 10

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

Front 11

periderm

Back 11

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

Front 12

cellulose

Back 12

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

Front 13

lignin

Back 13

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

Front 14

carbohydrate

Back 14

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

Front 15

symplasm

Back 15

entire mass of protoplasm of all the cells in the plant, interconnected by plasmodesmata. Symplast. Contrast with apoplasm

Front 16

apoplasm

Back 16

free spaces in plant tissue, Includes cell walls and intracellular spaces. Contrast with symplasm.

Front 17

gymnosperm

Back 17

plants with exposed seeds, usually within cones. "naked seeds". Contrast with angiosperm.

Front 18

tracheid

Back 18

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

Front 19

fiber

Back 19

(1) elongated, tapering, thick-walled cell that provides strength to wood. (2) smallest component of a rope.

Front 20

parenchyma cells

Back 20

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

Front 21

vessels

Back 21

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

Front 22

ring porous

Back 22

pattern of wood development in which the large- diameter vessels are concentrated in the earlywood. Contrast with diffuse porous.

Front 23

diffuse porous

Back 23

pattern of wood development in which the vessels and vessel sizes are distributed evenly throughout the annual ring. Contrast with ring porous.

Front 24

growth ring

Back 24

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 1 year of growth and are sometimes referred to as annual rings.

Front 25

sapwood

Back 25

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

Front 26

heartwood

Back 26

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

Front 27

ray

Back 27

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

Front 28

lenticel

Back 28

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

Front 29

apical bud

Back 29

bud at the top of a twig or shoot. See terminal bud.

Front 30

terminal bud

Back 30

bud at the tip of a twig or shoot. Apical bud. Contrast with lateral bud.

Front 31

lateral bud

Back 31

vegetative bud on the side of a stem. Contrast with terminal bud.

Front 32

axillary bud

Back 32

bud in the axil of a leaf. Lateral bud.

Front 33

dormant

Back 33

in a period of dormancy.

Front 34

apical dominance

Back 34

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

Front 35

adventitious bud

Back 35

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

Front 36

epicormic

Back 36

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

Front 37

node

Back 37

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

Front 38

internode

Back 38

region of the stem between two successive nodes. Contrast with node.

Front 39

branch collar

Back 39

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

Front 40

branch bark ridge

Back 40

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

Front 41

included bark

Back 41

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

Front 42

chloroplast

Back 42

specialized organelle found in some cells. Site of photosynthesis.

Front 43

chlorophyll

Back 43

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

Front 44

photosynthesis

Back 44

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.

Front 45

transpiration

Back 45

water vapor loss through the stomata of leaves.

Front 46

cuticle

Back 46

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

Front 47

stomata (stomates)

Back 47

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.

Front 48

guard cell

Back 48

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

Front 49

deciduous

Back 49

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). Contrast with evergreen.

Front 50

evergreen

Back 50

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

Front 51

abscission zone

Back 51

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

Front 52

petiole

Back 52

stalk or support axis of a leaf.

Front 53

anthocyanin

Back 53

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

Front 54

carotenoid

Back 54

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

Front 55

absorbing roots

Back 55

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

Front 56

lateral root

Back 56

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

Front 57

sinker roots

Back 57

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

Front 58

tap root

Back 58

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

Front 59

root crown

Back 59

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

Front 60

root cap

Back 60

section of tissue at the tip of a plant root. Contains statocytes which are involved in gravity perception of plants. Also protects growing tip.

Front 61

micorhyzea

Back 61

symbiotic association between certain fungi and roots of a plant.

Front 62

symbiosis (symbiotic)

Back 62

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

Front 63

photosynthate

Back 63

general term for the sugars and other carbohydrates produced during photosynthesis.

Front 64

antitranspirant

Back 64

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

Front 65

osmosis

Back 65

diffusion of water through a semipermiable membrane from a region of high water (low salt concentration) potential to a region of low water potential (high salt concentration).

Front 66

angiosperm

Back 66

plant with seeds borne in an ovary. Consist of two large groups: monocotyledons (grasses, palms, and related plants) and dicotyledons (mostly woody trees, shrubs, herbaceous plants, and related plants). Contrast with gymnosperm.

Front 67

angiosperm

Back 67

plant with seeds borne in an ovary. Consist of two large groups: monocotyledons (grasses, palms, and related plants) and dicotyledons (mostly woody trees, shrubs, herbaceous plants, and related plants). Contrast with gymnosperm.

Front 68

source

Back 68

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

Front 69

sink

Back 69

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

Front 70

axial transport

Back 70

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

Front 71

radial transport

Back 71

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

Front 72

plant growth regulator

Back 72

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

Front 73

plant hormone

Back 73

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. See plant growth regulator.

Front 74

auxin

Back 74

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.

Front 75

cytokinin

Back 75

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

Front 76

tropism

Back 76

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

Front 77

geotropism

Back 77

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

Front 78

phototropism

Back 78

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

Front 79

decurrent

Back 79

rounded or spreading growth habit of the tree crown. Contrast with excurrent.

Front 80

excurrent

Back 80

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

Front 81

compartmentalization

Back 81

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

Front 82

CODIT

Back 82

acronym for Compartmentalization Of Decay In Trees. See compartmentalization.

Front 83

reaction zone

Back 83

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

Front 84

temperate

Back 84

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

Front 85

buttress roots

Back 85

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

Front 86

aerial roots

Back 86

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

Front 87

propagation

Back 87

process of increasing plant numbers, both sexually and asexually.

Front 88

ecology

Back 88

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

Front 89

monocots

Back 89

see monocotyledon

Front 90

monocotyledon

Back 90

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

Front 91

dicotyledon

Back 91

plant with two cotyledons in its embryo; netted or palmate leaf veins; and flowers with three, four, or five petals in multiple of these numbers. Contrast with monocotyledon.

Front 92

fronds

Back 92

large, divided lead structures found in palms and ferns.

Front 93

leaf axil

Back 93

point of attachment of a leaf petiole to a stem.

Front 94

inflorescence

Back 94

cluster of flowers.

Front 95

root initiation zone

Back 95

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

Front 96

root mat

Back 96

dense network of roots near the base of a palm.

Front 97

companion cell

Back 97

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

Front 98

respiration

Back 98

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

Front 99

sieve cell

Back 99

long, slender phloem cell in gymnosperms.

Front 100

sieve tube elements

Back 100

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