Plant Term Glossary

Oregon Biodiversity Information Center
About ORBIC
Rare Species of Oregon
About Species Ranking
Rank Definitions
Rank Documentation
Survey and Manage Assessment
Endangered Invertebrate Program
Natural Areas Program
Natural Areas Plan
Register of Heritage Resources
Dedicated Conservation Areas
Research Natural Areas
Invasive Species
Invasive Plants in Oregon
Invasive Species Links
Rare Plant Information
T&E Plant Guide
T&E Plants by Basin
Biodiversity Data and Services
Data Requests
Submit Data
Publications and Reports
Staff and Contacts
Employment
Links
Site Index
 

Achene

A non-fleshy, 1-seeded fruit.

Alternate

Type of leaf arrangement in which only a single leaf is attached at each node. Term may also apply to other plant structures attached one per node.

Annual

A plant with a 1-year life cycle, growing from seed, producing flowers and fruits, and dying in 1 year.

Anther

The pollen-bearing part of the stamen.

Appressed

Lying close and flat against another part.

Auricle

A small projecting lobe or appendage, as found at the base of leaf blades of some species of the grass family (Poaceae).

Awn

A slender bristle-tip.

Awnless

Lacking an awn.

Axil

The point of the angle between the stem and leaf attachment.

Banner

The enlarged upper petal of a flower of the pea family (Fabaceae).

Basal

Related to, or located at the base.

Beak

A prolonged, usually narrowed tip of a thicker structure, as in some fruits and petals.

Beaked

Ending in a beak.

Biennial

A plant that lives for two growing seasons, usually flowering only in the second year.

Bilateral (symmetry)

Divisible into identical halves in only one plane; found in "irregular" flowers such as orchids.

Blade

The expanded, flattened part of a leaf or petal.

Bract

A reduced leaf subtending a flower, usually associated with the inflorescence.

Bristle

A hair-like structure; in members of the sunflower family (Asteraceae), it refers to one type of pappus, while in certain members of the sedge family (Cyperaceae) it refers to reduced perianth parts.

Bulb

A short, vertical underground shoot which has modified leaves or thickened leaf bases developed as food storage organs.

Bulbil

A small bulb.

Calcareous

Referring to limestone or lime-rich soils.

Callus

A firm thickening, like the thickened base of the lemma of many grasses (Poaceae).

Calyx

Outer whorl of flowering parts, collective term for all the sepals of a flower, (plural = calyces).

Capsule

A dry fruit that opens by slits, lids, pores, or teeth to release seeds.

Catkin

An inflorescence composed of an often drooping, or pendulous, cluster of unisexual, petal-less flowers, typical of wind pollinated trees and shrubs, such as willows, cottonwoods, oaks, and birches; also called an ament.

Chaffy

Covered by thin, dry scales.

Clasping

Leaf base partly or wholly surrounding the stem.

Cobwebby

With the appearance of spider webbing, usually referring to very fine hairs.

Column

A group of united filaments.

Compound (leaf)

A leaf divided into leaflets.

Congested

Crowded, as in an inflorescence with many densely clustered flowers.

Connate

Grown together or attached in a circle.

Contracted

Narrowed in a particular place.

Corolla

Collective term for all the petals of a flower, these petals may be separate or fused together.

Cotyledon

A leaf of the embryo of the seed.

Deciduous

Falling off; not permanent or evergreen.

Decumbent

Resting on the ground, but with the tip rising up (in contrast to prostrate, in which a structure lies completely flat on the ground).

Dehiscent

Splitting open along regular lines, as in a fruit or anther.

Disk

The tubular flowers found at the center of the flower head of many members of the sunflower family (Asteraceae).

Dolabriform (hair)

Pick-shaped; attached along the middle.

Ecotype

Genetically distinct individuals of a species that are adapted to a particular environment.

Elliptic

Oval shaped, with the ends rounded and the widest point at the middle.

Entire

Undivided; in leaves; having even-edged leaf margins rather than incised or toothed.

Erect

Upright in relation to the ground.

Evergreen

Bearing green leaves or stems over the winter; not deciduous.

Farinose

Covered with a meal-like powder.

Fertile

Bearing or producing reproductive structures.

Fibrous (roots)

Roots with several to many more or less equal branches; lacking a large central taproot.

Filiform

Very slender, threadlike.

Flaccid

Weak and lax.

Frond

The leaf of a fern.

Fruit

The ripened, seed-containing reproductive structure of a plant.

Galea

Upper lip enclosing the anthers in the paintbrush genus (Castilleja)

Gametophyte

The generation which has n chromosomes and produces gametes as reproductive bodies.

Glabrous

Without hairs.

Gland

A depression or appendage which usually secretes a sticky fluid.

Glandular

Bearing glands.

Glaucous

Covered with a waxy coat, often whitish or bluish in color.

Glumes

The pair of bracts at the base of a grass spikelet.

Head

A dense cluster of flowers, usually nearly spherical in outline. Individual flowers in the head are usually sessile or nearly so.

Herbaceous

Non-woody; dying to the ground each year.

Hood

Erect or spreading petal-like blade with incurved margins in the milkweed family (Asclepiadaceae).

Horn

An appendage extending from the hood in the milkweed family (Asclepiadaceae).

Indusium

A covering over the cluster of sporangia in many ferns.

Inflated

A structure that is bladdery or expanded like a balloon.

Inflorescence

The flowering part of a plant, usually referring to a cluster of flowers on a single stem.

Inrolled

Curled or curved inwards; involute.

Internode

The portion of a stem between two successive nodes, the gap between successive points of attachment of leaves on a stem.

Interrupted

Discontinuous; in an inflorescence, having clusters of flowers interspersed with bare areas of stem.

Involucre

A whorl of bracts located beneath (subtending) a flower cluster, as in the heads of members of the sunflower family (Asteraceae).

Keel

A prominent ridge shaped like the keel of a boat; in some members of the pea family (Fabaceae) referring to the lower, boat-shaped petal of the flower that encloses the ovary and stamens.

Lacerate

With an irregularly-jagged margin.

Lanceolate

Lance-shaped, much longer than broad and tapering to a tip.

Lateral

On or at the side.

Leaflet

Any subdivision of a compound leaf.

Lemma

The larger of the two bracts (the other being the palea) that enclose the stamens and pistil in a grass floret.

Ligule

Membranous structure or fringe of hairs found at the junction of the leaf blade and sheath of grasses.

Linear

Several times longer than wide, usually refers to very narrowly shaped leaves or fruits.

Lip

The lowermost, often highly modified, petal of some flowers as in orchids, mints, and penstemons.

Lobe

A division or segment of a structure, usually rounded in outline.

Margin

An edge, as in the edge of a leaf blade.

Mealy

Soft, dry, and crumbly textured, as in certain fruits.

Membranous

Thin, soft, and pliable.

Midrib

The main, central vein of a leaf, bract, scale, or petal.

Mucilaginous

Slimy.

Node

The point of attachment of a leaf or leaves on a stem; the joint of a stem.

Nutlet

A small, one-seeded, nut-like structure; the specialized fruit of members of the borage (Boraginaceae) and mint families (Lamiaceae).

Oblanceolate

A structure that is broadest near the tip and tapering to a narrower base.

Oblong

Much longer than broad, with nearly parallel sides; wider than linear.

Once-pinnate

A compound leaflet divided into entire leaflets (the leaflets are not further divided into lobes or secondary leaflets).

Opposite

Type of leaf arrangement in which two leaves are attached on opposite sides of a stem at the same node.

Ovary

The part of the pistil of a flower that contains the ovules.

Ovate

Egg-shaped, with the broadest end toward the base.

Palea

The smaller of the two bracts (the other being the lemma) that enclose the stamens and pistil in a grass floret.

Palmate

Lobed or veined with 3 or more branches or veins arising from a common point, like the fingers of a hand.

Panicle

A much-branched inflorescence in which the central axis (main stem) bears flowering branches which are themselves branched again.

Pappus

The modified sepals (calyx) of members of the sunflower family (Asteraceae) found at the top of the fruit in the form of thin bristles, feather-like plumes, scales, or sharp awns.

Partition

Line separating the two halves of the fruit of a mustard (Brassicaceae).

Pectinate

Resembling a comb in having very narrow parallel segments borne at a right angle to the main axis.

Pedicel

The stalk of a single flower in a flower cluster, a single fruit, or a single grass spikelet.

Peduncle

The stalk of a flower or flower cluster.

Perennial

A plant which lives for three or more years.

Perianth

Collective term for the calyx and corolla of a flower.

Pericarp

The wall of the fruit.

Perigynium

Sac-like structure enclosing the fruit in species of the cyperus family (Cyperaceae). Plural = perigynia.

Persistent

Remaining attached, as in the calyx on a fruit or remnant, dead leaves.

Petal

The usually colored, individual components of the corolla of a flower.

Petiole

A leaf stalk.

Pinnae

One of the primary divisions of a compound leaf.

Pinnate

With leaflets, lobes, or veins originating from several different points on each side of a main axis, as in the structure of a feather.

Pinnately compound

Division of a leaf blade into leaflets arranged on each side of a common leafstalk.

Pistil

The ovule-bearing structure of a flower, consisting of a stigma, style, and ovary; the "female" part of a flower.

Pistillate

With pistils, but lacking stamens; "female".

Plumose

Feathery.

Pod

Any dry, dehiscent fruit, such as that of many members of the pea family (Fabaceae).

Prostrate

Lying flat upon the ground (in contrast to decumbent in which a structure lies flat on the ground except for the tip which rises upward).

Pubescence

Any type of hair-like structure on a plant part.

Pubescent

Having hairs.

Raceme

An elongate inflorescence made up of stalked flowers attached directly to the main axis.

Rachis

A main axis, such as that of a compound leaf.

Ray

The strap-like flowers at the margin of a head in members of the sunflower family (Asteraceae); a primary branch of the inflorescence in members of the parsley family (Apiaceae).

Recurved

Curved downward or backwards.

Reflexed

Abruptly bent downward or back.

Reticulate

Forming a network pattern.

Rhizomatous

Bearing rhizomes.

Rhizome

An underground stem or rootstock bearing reduced, scaly leaves.

Rib

Prominently raised vein or wing-like structure.

Rootstock

Slow-growing, woody upright underground base of a perennial herb that gives rise to yearly growth of stems and leaves; caudex.

Rosette

A crowded cluster of leaves located at, or near the ground, at the base of a stem.

Runner

A slender stolon.

Scabrous

Rough to the touch like sandpaper, usually due to very short, stiff hairs or outgrowths of the epidermis.

Scale

Any thin, short, often membranous structure; in the sedge family (Cyperaceae) often used in reference to the bracts that subtend individual staminate and Distillate flowers; small, sharp-tipped leaves of certain clubmosses (Lycopodiaceae).

Secund

Oriented on one side of an axis, as in fruits or flowers all being on one side of a stem.

Sepal

An individual leaf-like segment of the calyx of a flower.

Sessile

Lacking a stalk, attached directly at the base (as in a leaf without a petiole).

Sheath

The lower part of the leaf that enfolds the stem in grasses, sedges, and rushes; in horsetails (Equisetum) used to describe the ring of papery leaves at each stem joint.

Shrub

A woody plant with several equally large stems from the base, usually less than 4.5 m tall.

Silique

A fruit type found in certain members of the mustard family (Brassicaceae) characterized by its long, slender shape that is typically 3 or more times longer than wide.

Simple

Unbranched or undivided; in leaves refers to condition in which leaves are not divided into leaflets.

Sorus

A cluster of sporangia (plural=sori).

Spike

An elongated inflorescence of sessile flowers or florets.

Spikelet

The basic unit of the inflorescence of grasses and sedges. In grasses (Poaceae), it is composed of a pair of basal glumes subtending 1 or more florets. In sedges (Cyperaceae) it consists of a single bract subtending a flower.

Sporangium

A case or container for spores (plural=sporangia).

Spore

The reproductive body produced and dispersed by ferns, horsetails, club mosses and other "lower" vascular plants that do not reproduce by true seeds.

Sporophyll

A leaf which bears or subtends 1-more sporangia.

Spreading

Diverging at nearly a right angle from a structure; nearly prostrate.

Spur

A tubular or sac-shaped extension of a petal or sepal.

Stamen

The pollen-producing structures of a flower; the "male" part of a flower.

Staminate

With stamens, but lacking a pistil; "male".

Staminode

A modified stamen which does not produce pollen.

Sterile

Non-fertile; structure lacking reproductive parts or abilities.

Stigma

The surface of the pistil on which pollen grains land and germinate.

Stipule

Leaf-like or scaly appendages (typically paired) at the base of the petiole in many plants. These may be fused at the base as in some members of the pea family (Fabaceae).

Stolon

A horizontal stem, usually growing along the surface of the ground, often giving rise to new plants at its tip; runner.

Strobilus

Cone-like reproductive structure; spore-bearing structure of horsetails (Equisetaceae) and clubmosses (Lycopodiaceae; plural = strobili.)

Style

The portion of the pistil between the ovary and the stigma.

Subtend

To be situated immediately below, as in bracts beneath a flower.

Taproot

The primary root from which secondary (smaller, lateral) roots arise.

Tendril

A slender, coiling or twining organ by which a plant clings to a support.

Tepal

A segment of the perianth not clearly differentiated between sepals and petals.

Terminal

Located at the tip of a structure.

Ternately compound

Divided into threes, as in a leaf consisting of three leaflets.

Tooth

Any small, marginal lobe, usually on the edge of a leaf blade.

Tufted

A close-growing cluster of stems, as in certain bunchgrasses, sedges, and mat-forming herbs.

Tussock

A compact, densely tufted growth form of some grasses and sedges.

Twig

The current year's growth of a woody stem; the endmost section of a branch.

Umbel

A flower cluster in which the individual flower stalks arise from a common point, like the rays of an umbrella.

Valve

One of the segments into which a dehiscent fruit separates.

Vegetative

A sterile structure of a plant, not associated with the production or dissemination of seeds, spores, or pollen.

Vein

A vascular bundle of a leaf or petal; nerve.

Viscid

Sticky; with sticky exudates.

Whorl

a ring of 3-more similar structures radiating from a common point.

Wing

A thin, often dry or leaf-like extension bordering a structure; also referring to the 2 lateral petals of the flower in some members of the pea family (Fabaceae).

Woolly

with long, interwoven hairs.
Photo of the Illinois River
© Larry N. Olson
 

 © 2014 Institute for Natural Resources