Tree Biology & Mechanics. Pt.1: Wood Structure

Front 1

angiosperm

Back 1

plant with seeds 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) ( contrast with gymnosperm)

Front 2

annual rings

Back 2

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

Front 3

buttress root

Back 3

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

Front 4

cambium

Back 4

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

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cellulose

Back 5

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

Front 6

compression

Back 6

in mechanics, the action of forces to squeeze, crush, or push together any material or substance ( contrast with tension)

Front 7

compression wood

Back 7

reaction wood in gymnosperms, and some angiosperms, that develops on the underside of branches or leaning trunks and is important in load bearing (contrast with tension wood)

Front 8

decay

Back 8

process of degradation by micro-organisms

Front 9

earlywood

Back 9

portion of an annual ring (growth ring) that forms during spring, characterized by large-diameter cells and thin walls. Also called springwood (contrast with latewood)

Front 10

fiber

Back 10

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

Front 11

flexure wood

Back 11

response growth triggered by the continued flexing of the tree stem or branch

Front 12

gymnosperm

Back 12

plants with exposed seeds, usually within cones (contrast with angiosperm)

Front 13

latewood

Back 13

portion of an unusual ring (growth ring) that forms during summer, characterized by small-diameter cells with thick walls. Summer wood (contrast with earlywood)

Front 14

lignin

Back 14

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

Front 15

mechanical stress

Back 15

a measure of the internal forces acting within a deformable body; force per unit area

Front 16

meristematic tissue

Back 16

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

Front 17

parenchyma

Back 17

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

Front 18

phloem

Back 18

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) (contrast with xylem)

Front 19

ram's horn

Back 19

inward curling formation of woundwood resembling the horns of a ram

Front 20

rays

Back 20

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

Front 21

reaction wood

Back 21

wood formed in leaning or crooked stems, or on upper or lower sides of branches, as a means of counteracting the effects of gravity (see compression wood and tension wood)

Front 22

response growth

Back 22

new wood produced in response to loads to compensate for higher strain in outermost fibers; includes reaction wood (compression and tension) and woundwood

Front 23

retrenchment

Back 23

natural process during which an overly mature tree reduces its crown and increases its girth to consolidate resources and increase longevity; the deliberate process of reducing tree height to mimic natural processes

Front 24

secondary xylem

Back 24

xylem produced to the interior of the vascular cambium during secondary growth

Front 25

strain

Back 25

the deformation resulting from a stress, measured as a change in specimen length per unit of total length

Front 26

tension

Back 26

in mechanics, the action of forces to stretch or pull apart any matetial or substance (contrast with compression)

Front 27

tension wood

Back 27

a form of reactionwood in broadleaved trees (hardwoods) that forms on the upper side of branches or the trunks of learning trees

Front 28

tracheid

Back 28

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

Front 29

vascular cambium

Back 29

lateral meristem from which secondary xylem and secondary phloem originate (see cambium)

Front 30

vessel

Back 30

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

Front 31

woundwood

Back 31

lignified, differentiated tissues produced on woody plants as a response to wounding

Front 32

xylem

Back 32

main water- and mineral-conducting tissue in trees and other plants. Provides structural support (contrast with phloem)