Basics of Plant Taxonomy

Acaulescent

lacking a main stem, stemless

Achene

a small dry seed typical in Asteraceae & Cyperaceae; they do not split open at maturity

Actinomorphic

regular, radially symmetrical

Alternate

a leaf arrangement in which the leaves originate in an alternate fashion up the stem; only a single leaf is attached at each node

Anther

the pollen-bearing portion of a stamen, male

Awn

a slender, stiff terminal bristle attached at its base to another structure. In grasses, awns typically extend from the lemmas of the florets.

Auricle

a small earlike lobe or appendage

Bilabiate

having two labia (upper and lower)

Bipinnate

twice pinnately compound

Biternately compound

compound leaf, thar is divided into three primary parts (ternate), and each of those three parts is further divided into three leaflets

Blade (Lamina)

the expanded terminal portion of a leaf, petal or other structure, i.e. that portion of the leaf that does not include the stalk or petiole

Bract

a modified leaf which may be reduced in size or different in other characteristics from the foliage leaves and which usually subtends a flower or an inflorescence (They sit on the stem just below a flower, flower stalk, or inflorescence)

Calyx

the outer whorl (layer) of the perianth, composed of the sepals, usually but not always green, which enclose other flower parts in bud

Campanulate

Bell Shaped (Campanula)

Cypselae

a dry single seeded fruit formed from a double ovary, or which only one forms a seed (characteristic of Asteraceae)

Capsule

a dry, generally many-seeded fruit

Catkin

drooping group of flowers (Oaks)

Compound

made up of two or more similar parts, as in a leaf which has leaflets

Corolla

the inner whorl of the perianth, between the calyx and the stamens, a collective term for the petals of a flower

Corymb

a broad, flat-topped inflorescence in which the marginal flowers open first

Costa

mid-vein of leaf, typically used in ferns

Cyme

a broad, flat-topped inflorescence in which the central flower is the first to open

Decumbant

prostrate at the base but ascending at the end

Deflexed

bent down or backward

Dehiscent

opening spontaneously when ripe to discharge the seed

Deltoid

broadly triangular in shape

Dioecious

having staminate and pistillate flowers on separate plants (male & female plants)

Drupe

a fleshy indehiscent fruit enclosing a nut or hard stone (e.g. peach);

Elliptical

broadest near the middle and tapering gradually to both ends;

Filament

the basal, sterile portion of a stamen below the anthers;

Fimbriate

having a fringed margin;

Funnelform

a flower that widens gradually from the base;

Frond

a large compound leaf, typically used for ferns

Glabrous

without hair

Glaucous

covered with a thin, light-colored wax or powder

Glandular

producing tiny globules of sticky or oily substance (Glands)

Glomerule

a head or dense cluster of flowers (e.g. Juncus)

Hypanthium

floral cup is a structure where basal portions of the calyx, the corolla, and the stamens form a cup-shaped tube

Hypogynium

That structure which supports the ovary in such plants as sedges

Indehiscent

not opening by itself, of a seed pod

Inflorescence

the flowering portion of a plant

Involute

with both edges enrolled or folded, toward the midvein

Internode

the portion of a stem between two successive nodes;

Joint

the point on a plant stem from which a leaf or leaf-bud grows, aka node;

Lacerate

irregularly cut of cleft;

Lanceolate

Significantly longer than wide and widest below the middle, gradually tapering toward the apex;

Leaflet

one segment of a compound leaf;

Lobe

usually a rounded segment

Membranous

thin, flexible and more or less translucent

Monecious

having staminate and pistillate flowers on the same plant (male and female)

Node

a point on a stem where leaves or branches originate

Nut

a dry, usually one-seeded, indehiscent fruit with a hard walled exterior

Oblong

two to four times longer than broad

Obovate

inversely ovate

Opposite

a leaf arrangement in which the leaves originate in an opposite fashion up the stem

Orbicular

having the shape of a ring or disc

Ovary

the basal portion of a pistil where female germ cells develop into seeds after germination

Ovate

egg-shaped, wider below the middle

Ovoid

an egg-shaped solid

Palmate

radiating from a single point like the spreading fingers of an outstretched hand

Panicle

an elongated, branched inflorescence with sessile or nearly-sessile flowers

Pappus

the bristles, hairs or scales at the apex of an achene in the Asteraceae

Peduncle

stalk of a flower

Perianth

a collective term for the calyx and corolla

Petal

a single segment of a divided corolla

Petiole

the stalk of a leaf

Phyllary

one of the bracts below the flowerhead in the Asteraceae

Pinna

leaflet of a fern

Pinnate

with separate segments that are arranged feather-like on either side of a common axis

Pinnule

Any of the ultimate leaflets of a bipinnate or tripinnate leaf; a subleaflet

Pistil

the central reproductive organ of a flower, consisting of ovary, style and stigma, female

Pome

fleshy indehiscent fruit derived from an inferior, compound ovary (e.g. apple)

Prophyllate

subtended by prophylls

Prophylls

bracteole subtending an individual flower;e.g., in some species of Juncus

Pubescent

general term describing the presence of hairs

Raceme

an elongate, unbranched inflorescence with pedicelled flowers on the main stem

Rachis

main axis of a structure, typically an inflorescence or leaf

Reflexed

abruptly pointed or bent backwards

Retrorse

Bent or turned backward or downward; (e.g., hairs pointing down a stem)

Rhizome

an underground stem capable of producing new stems or plants at its nodes

Rotate

flower that is circular and flattened

Sagittate

arrowhead-shaped, with two retrorse basal lobes

Sepal

a single segment of a divided calyx

Serrate

having sharp, forward-pointing teeth on the margin

Serrulate

serrate with very small teeth

Sheath

a leafy, tubular structure usually on a sedge or grass that envelopes the stem

Silique

Dry, dehiscent, variously shaped,many-seeded,2-valved capsule with valves splitting from the bottom and leaving a false partition known as a replum

Simple

a leaf that has one part, not subdivided into leaflets

Sori

a cluster of sporangia on the back of a fen leaf

Spadix

Spike like inflorescence born on fleshy stem (typical Arisaema)

Spatulate

Spatula-shaped; rounded above and gradually narrowed to base

Spiral

a leaf arrangement in which the leaves originate in a spiral fashion up the stem

Spike

an elongated, unbranched inflorescence with sessile or nearly-sessile flowers

Sporophyte

Fertile (i.e. Spore bearing) portion of plant, typically ferns or mosses

Stigma

the terminal portion of a pistil, which receives the pollen

Stipule

an appendage at the base of a petiole, usually in pairs

Stolon

an elongated horizontal shoot above the ground, rooting at the nodes or apex

Strobilus

A usually globose or cylindrical structure involved in reproduction and composed of an axis with a spiral, usually dense aggregation of sporophy (a.k.a. Cone)

Style

the narrowed portion of a pistil between and connecting the ovary and the stigma

Taproot

the primary root continuing the axis of the plant downward often quite deeply into the ground