Dendrology

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abscission

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The falling away of a leaf or other organ caused by the breakdown of a layer of thinwalled cells at the base of the structure

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Achene

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a small, dry indehiscent fruit with a single seed. Some achenes have a plumed or feathery tails, some do not. compare with nut and samara

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acicular

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needle-shaped long narrow and tapering to a distinct sharp point

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acom

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a nut capped by a scaly or bristly base (an involucre)

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acuminate

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tapering to a long sharp point with concave sides. Often used to describe the apex of a leaf

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acute

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tapering to a pointed apex with more or less straight sides. compare with acuminate

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adnate

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the fusion or joining of unlike parts. For example a fruit joined directly to a bract rather than to the stem

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adventitious

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structures or organs developing in an unusual position, such as roots developing from the stem

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aggregate fruit

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commonly applied to a cluster of small fleshy fruits that originate from separate pistils in a single flower. for example the fruits of raspberries or blackberries

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alternate

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bome singly at a node. If leaves are alternate, only one leaf arises from each point on the stem. compare with opposite

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ament

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a long, thin inflorescent composed of sessile, unisexual flowers (male or female, but not both) compare with raceme and catkin

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angiosperm

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a group of plants that produce flowers and seeds bome inside ovaries (fruits). compare to gymnosperms

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apex

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the tip. the point of a leaf farthest from its point of attachment to the twig. compare to base and margin

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apical

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located at the apex

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apophysis

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the portion of a cone scale that is exposed when the cone is closed

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appressed

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pressed closed or flat against something--like a bud appressed to a twig

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arcuate

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curved into an arch. Leaf veins are said to be acruate when they start at the midrib but end up paralleling the margin

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aril

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a fleshy appendage that grows from the base of a seed to cover some or all of the seed. compare with ovary. the fruit of yews are arils

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armed

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bearing thorns, spines, barbs, or prickles

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asexual

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reproducing without sexual union

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awl-like

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short and narrowly triangular. rapidly tapering to a sharp tip. like sewing awl. compare with aclcular and linear

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bark

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all layers of a woody stem (living and dead) external to the vascular cambium

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base

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bottom, near the point of attachment. the base of the leaf blade occurs where it is attached to its petiole

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berry

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a fleshy fruit developing from a single pistil with many seeds imbedded inside. Tomatoes and blueberries are examples. compare with drupe and pome

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bisexual

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a flower with both male and female organs; perfect

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blade

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the broad part of a leaf or petal

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bloom

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a whitish waxy or powdery covering on leaves, flowers, fruits, or stems. compare with glaucouc

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bole

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the trunk of a tree

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boss

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a projection from the surface of an organ, a bump

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bract

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a modified leaf that occurs at the base of a flower or inflorescence may be small and inconspicuous or large and brightly colored. In cones, bracts separate seeds from the cone scales. Compare with involucre

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broadleaf

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a general category of plants based roughly on the width of the leaf blade. generally used to refer to all trees and shrubs that are angiosperms -generally contrasted with conifers

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bud

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an undeveloped shoot or flower

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calyx

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a collective term for all the sepals of a flower. compare with corolla

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cambium

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a tissue composed of cells capable of active division, a lateral meristem that results in increased diameter growth. Vascular cambium produces xylem and phloem cells; the cork cambium produces cork and phelloderm

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capsule

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a dry, dehiscent fruit composed of more than one fused carpels. compare with legume and follicle

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carpel

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the female organ of a flowering plant. a simple pistil from one modified lead, or one part of a compound pistil formed from one modified leaf

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catkin

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a long, thin inflorescence composed of sessile, unisexual flowers. compare to raceme and ament

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chlorophyll

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The green pigment in plants responsible for photosynthesis

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clone complete

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a group of individuals arising from a single parent via vegetative reproduction. with all the parts typically belonging to something. For example, a flower is said to be complete if it includes sepals, petals, pistils and stamens. compare with incomplete, perfect, and imperfect

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compound

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with two or more parts in one organ. A leaf is said to be compound when a single petiole bears more than one blade. Each blade is then referred to as a leaflet. See simple, pinnately compound and palmately compound.

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cone scale

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the thickened, woody portion of conifer cone. Pine cones are comprised of several to many woody scales

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conifer

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the group of plants whose seeds are borne inside cones (rather than ovaries). see cone scale, bracts, and seeds

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corolla

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the collective name for all petals of flower. compare with calyx

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cortex

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a primary tissue of roots and stems derived from the corpus meristem; root tissue between the epidermis and the vascular bundle

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cotyledon

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a primary leaf of the embryo; a seed lead the first leaf to emerge from a seed

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crenate

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with rounded teeth along the margin. compare with serrate and dentate

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cultivar

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a form of plant originating under cultivation

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cuticle

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the waxy layer on the surface of a leaf or stem

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deciduous

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falling of. not persistent; not evergreen

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decussate

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arising from the stem in pairs, with each at right angles to the pair above or below it. compare with ternate, spiral, alternate, opposite

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dehiscent

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opening at maturity along predetermined sutures (typically to release seeds). Compare with indehiscent

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deltoid

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triangular

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dentate

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toothed along the margin, with the teeth directed outward 9perpendicular to the midrib) rather than forward. Compare with serrate and crenate

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determinate

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describes an inflorescence in which the terminal flower develops first, halting further elongation

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dioecious

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flowers imperfect, with staminate and pistillate flowers bome on separate plants. Compare with monoecious

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distal

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toward the tip

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distichous

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in two vertical rows arising on opposite sides of axis; two ranked.

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dorsal

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the back or outward surface. Compare with ventral

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doubly serrate

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having large teeth interspersed with small teeth in a regular fashion

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drupe

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a fleshy, indehiscent fruit usually containing a single, hard seed-like cherry or plum

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elliptical

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a narrow oval with the broadest part in the middle and narrower at the equal-sized ends

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emarginated

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notched at the apex

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entire

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smooth-not toothed, notched, lobed, or divided

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erect

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vertical, not spreading

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even-pinnate

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Pinnately compound with a pair of leaves at the apex. Resulting in an even number of leaflets. also termed paripinnate

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Evergreen

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Not deciduous; retaining leaves for longer for longer than one growing season. Compare with deciduous

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exfoliating

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peeling off in thin layers or flakes

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fascicle

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A tight bundle or cluster. The needles of pine trees are borne in fascicles

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fertilization

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the union of the male and female gamete to form a zygote

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flower

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the reproductive organ of a flowering plant. A complete flower consists of sepals, petals, pistils, and stamens

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follicle

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a dry dehiscent fruit composed of single carpel and opening along a single side. compare with achene, legume, and capsule

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ruit

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a ripened ovary, including the seeds and any other attachments within it. Compare with seed, cone, and aril (see these fruit types for illustration)

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furrowed

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an alternating series of ridges and grooves, often irregular. Many species of trees have furrowed bark

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genus

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a taxonomic unit composed of similar species. similar genera are grouped into families. compare with species

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glabrous

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smooth or hairless

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gland or glandular

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bearing glands (structures that secrete sticky or oily substances)

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glaucous

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covered with bloom

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gymnosperm

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plants producing seeds that are not enclosed inside ovaries. Seeds are usually, but not always, borne inside cones. Compare with angiosperms

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habit

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the characteristic form of a plant; the manner in which it typically grows.

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hardwood

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a category of trees based roughly on the hardness of their wood. Most broadleaved trees are classes as hardwoods

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imbricate

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overlapping-like shingles on a roof or scales on a fish

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imperfect

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a flower missing either its stamen or pistils. unisexual

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incomplete

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missing any of its normal parts. a flower is incomplete if it is missing any of the following parts; pistil, stamen, sepals, petals.

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indehiscent

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not splitting open at maturity along predetermined lines. staying closed compare with dehiscent

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inflorescence

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a collection of flowers sharing a common stalk. see ament, head, raceme

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internode

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The portion of a stem between leaf nodes. Also, used with conifers to indicate the portion of branch between whorls of smaller branches

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involucre

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a whorl of bracts subtending a flower or inflorescence. the cap of an acorn is an involucre

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lanceolate

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lance-shaped. much longer than wide, with the widest part below the midpoint

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lateral

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bome on the side. compare with terminal

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leaf

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a flattened, expanded portion of the stem that is usually photosynthetic. the parts of complete include, blade, the petiole, and sometimes stipules. in compound leaves, a single leaf is composed of multiple leaflets

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leaf scars

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the scar or mark let on a twig when a lea falls or is removed

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leaflets

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one blade of a compound leaf

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legume

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a dry, dehiscent fruit derived from a single carpel and usually opening along two lines of dehiscence. for example a pea pod.

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lenticle

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a slightly raised. Pore on the surface of a young twig. often lens-shaped and corky. arises from an epidermal cell. aids the plant in breathing

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linear

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long and narrow with almost parallel sides.

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lobe

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a rounded or pointed projection of an organ for which the sinus extends 1/4 to 1/2 way toward the center

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margin

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edge, as the edge of a leaf

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meristem

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undifferentiated, actively dividing tissues that result in plant growth. Primary meristems occur at the growing tips of shoots and roots, and result in elongation.secondary meristems include the vascular and cork cambia and result in diameter growth

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midrib

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the central rib or vein of a leaf or other organ. also called a midvein

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monoecious

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denotes plants in which the male and female flowers (each unisexual) occur on the same plant

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multiple fruit

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a fruit formed from several separate flowers crowded together on the same axis like a pineapple or mulberry

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mycorrhiza

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a symbiotic relationship between a fungus and a root

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naked

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uncovered. lacking hair or scales. buds naked when they are not covered with scales

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nectar

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a sugary, sticky fluid secreted by many plants to attract pollinators

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nectar guides

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lines or spots directing pollinators toward nectaries; often invisible except under ultraviolet light

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node

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the place on a stem where leaves or branches originate

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nut

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a hard, dry indehiscent fruit usually containing a single seed

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ob-

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prefix meaning inverse or reverse direction.

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odd-pinnate

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pinnately compound leaf ending with a single leaflet, resulting in an odd number. Also termed imparinnate.

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opposite

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when two leaves (or other organs) arise from the stem directly across from one another.

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organ

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a plant part with a specific function-like leaves, shoots, and roots

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oval

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broadly elliptical, with the width over 1/2 the length

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ovate

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egg-shaped, with the point of attachment at the broad end

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palmate

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lobed, veined, or divided from a common point

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palmately compound

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a compound leaf in which the leaflets arise from a common point.

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palmately veined

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when the primary veins of leaf arise from a common vein.

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panicle

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a branched, racemose inflorescence in which the flowers mature from the bottom upwards.

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pedicel

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the stalk of a single flower or an inflorescence.

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peltate

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shield shaped. a flat surface borne on a stalk attached to it middle

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penniveined

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pinnately veined. Veined in a fashion resembling a feather.

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perfect

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a flower containing both sexual organs - a pistil and stamens

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persistent

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remaining attached after similar parts are normally dropped.

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petal q

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an individual segment of the corolla- often brightly colored and scented to attract pollinators; often absent in wind-pollinated species. thought to be modified leaves

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petiolate

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having a petiole

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petiole

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the stalk of a leaf. in a compound leaf, the part of the stalk below the lowest set of leaflets. the stalk on each leaflet of a compound leaf is called a petiolule

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phloem

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the food conducting tissue of vascular plants.

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phyliotaxy

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the arrangement of leaves around a stem. in broadleaves, typically expressed as a fraction in which the numerator indicates the number of revolutions around a leaf required in moving from one leaf to another directly above it on the stem

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pinnately compound

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a compound leaf in which the leaflets arise along a central axis, rather than from a common point.

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pinnately veined

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veined a pinnate fashion-or penniveined

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pistil

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the female reproductive organ of a plant, consists of a stigma, style and ovary.

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pistillate

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having a pistil, but not stamens

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pitch

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another term for resin, a sticky substance produced by some plants as a part of their defense mechanism. typically called resin while inside the plant and pitch once its outside the plant

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pith

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the central portion of most plants. typically spongy when young, but may turn hard with age. may be solid, chambered, or hollow. typically round, but amy be other shapes in some species

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pod

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any dry, dehiscent fruit, especially a legume or capsule

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pollen

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microspores of seed plants that contain the male gametes

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pollination

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the transfer of pollen from the anther to the stigma

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pome

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a fleshy, indehiscent fruit, typically with multiple sees enclosed inside a papery core.

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prickle

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a small, sharp projection arising from the bark--usually not containing vascular tissue. easy to break off

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prop root

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adventitious roots arising from the stem or branches and providing additional support to the structure from which they arise

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prostrate

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lying flat on the ground

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pubescence

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in general terms, it means any type of hairless. more technically, it means covered with short, soft hairs.

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pubescent

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bearing pubescence or any kind of hairs

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raceme

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an unbranched, elongated inflorescence containing flowers borne of stalks (pedicles). flowers may be perfect or imperfect. flowers mature from the bottom upwards

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rachis

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the main axis of compound leaf or flower. the part of the main rib between the first and last set of leaflets or flowers

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radicle

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the part of the plant embryo that develops into the primary root

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rank

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a verticle row of leaves or flowers. plants with two rows of leaves are said to be 2-ranked; three rows are 3 ranked. the denominator of the phyllotaxic fraction.

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resin

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a group of substances produced by plants as a defense mechanism against insects, disease, and other damaging agents. often sticky and acidic in nature;usually secreted by special cells into ducts or canals in the leaves or bark. some yield important commercial products like turpentine

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revolute

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rolled under. in leaves, with margins rolled down and under, sometimes loosely and sometimes very tightly

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rhizome

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a horizontal underground stem, unlike roots, rhizomes contain buds

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samara

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a dry, indehiscent, single seeded, winged fruit

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sap

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the juice of a plant -- both nutrient--laden water moving upward and food-rich water moving downward

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sapwood

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the outer, younger portion of a wood still active in the transport of water and nutrients, usually light in color.

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scale-like

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leaves that are small and lightly overlapping---typically flat in cross-section, but may also be rounded

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seed

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a ripened ovuie. seeds are composed of an embryo and nutritive tissue (cotyledon or endosperm). the development of seeds, which limits the importance of water in the germination process, was significant step forward in the colonization of dry land by plants

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seed coat

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the outer covering of a seed: typically must be broken or ruptured before germination can occur

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sepal

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a single segment of the calyx. typically green, but may be brightly colored

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serrate

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saw-toothed with the teeth pointing forward.

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sessile

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without a stalk or petiole

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sheath

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a papery covering--for example the bundle sheath that surrounds the bundle of pine needles

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shoot

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a young stem or branch

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shrub

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a woody plant, typically with multiple stems and smaller than a tree at maturity

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simple

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undivided-- a simple leaf has only one blade per petiole, a simple pistil has only one carpel

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sinus

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the indentation between two lobes

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softwood

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A category of trees based roughly on the hardness of their wood. all conifers are classified as softwoods

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species

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a group of individuals capable of interbreeding and producing fertile offspring. similar species are combined into a genus

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spike

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an unbranched, enlongated inflorescence with sessile or subsessile flowers maturing from the bottom up

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spine

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a modified leaf or stipule that is stiff, slender, and sharp. spines arise from below the epidermis and contain vascular tissue.

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spinose

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bearing spines

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spiral

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a type of leaf arrangement in which each node arises from the twig slightly above and to the side of the preceding node (in a spiral fashion).

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spray

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a small shoot or branch

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sour shoots

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short, stout twigs with little or no elongation between leaf nodes, often giving the appearance that leaves are whorled.

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stamen

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the male reproductive organ of a flower -- consistenting of an anther and filament

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staminate

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the male reproductive organ of a flower -- consisting of an anther and filament.

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Stele

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the primary vascular tissue of a stem or root, including all tissues internal to the vascular tissues. Occurs at the center of a stem or root

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stipule

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a small modified leaf that occurs near the base of the petiole in some species. If present, typically occurs in pairs; in some species, may be further modified into spines

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stolon

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a long horizontal stem that creeps along the ground and roots at the nodes

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stoma or stomata

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a pore or opening in the surface of a leaf for the purpose of gas exchange. Each stoma is surrounded by two guard cells that open and close the stoma. plural of stoma is stomata.

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strobile

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the reproductive structures of gymnosperms - the male strobile produces pollen and the female typically develops into cone. In angiosperms, a type of dry composite fruit whose seeds are achenes (resembles a cone) also called a strobilus

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sucker

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a shoot originating belo