Home :: Weed Department » Noxious Weeds Glossary

Alternate-leaves that are arranged singly up the stem; not opposite each other.
Annual-plant that germinates, flowers, seeds, and dies during one growing season.
Anther-structure in a flower in which pollen is formed
Auricle-lobe-like structure at the collar of a grass leaf.
Awn-slender bristle at the tip of grass seed structures.
Axil-the angle formed between a leaf and a stem.
Basal-at the base of a plant or plant part.
Biennial-plant that germinates in one growing season, then flowers, seeds, and dies during a second.
Bract-leaf-like structure at the base of flowers or leaves.
Calyx-all the flower leaves together, normally green in color.
Clasping leaves-leaves that appear to wrap around the stem at their base.
Compound leaves-leaves with 2 or more distinct leaflets.
Cotyledons-the first leaf-like structures that appear after germination; seed leaves.
Crown-the structure formed where leaves, stems, and roots grow together.
Dissected-deeply and repeatedly divided into smaller parts.
Entire-not toothed or otherwise cut.
Glumes-the 2 bracts surrounding a grass spikelet.
Head-a group of flowers borne tightly together.
Leaflets-leaf-like structures within a compound leaf.
Ligule-the structure at the collar of a grass leaf between the sheath and the stem.
Linear-long, narrow, and slender.
Lobed-a cut into a leaf from the edge toward the center; greater than toothed, but not quite compound.
Margin-the edge of a leaf.
Membranous-thin and flexible, usually not green.
Midrib-the center and usually most prominent vein on a leaf.
Nodding-a flower that is not pointed upward, but bent downward or sidewise to the stem.
Opposite-leaves situated directly across the stem from each other.
Ovate-egg shaped in outline.
Panicle-a much-branched inflorescence.
Perennial-a plant that lives for more than 2 growing seasons.
Petiole-a leaf stalk.
Pinnate-with 2 rows of leaflets, like a feather.
Plume-a hair-like or feather-like structure, often on a seed.
Pubescence-the hairs on a leaf, stem or flower.
Rhizome-a creeping, underground stem.
Rosette-a circular, normally basal, clump of leaves.
Sheath-the extension of leaf tissue surrounding a stem.
Simple leaf-one with a blade in one piece; not compound.
Spike-a narrow, non-spreading inflorescence.
Spikelet-a single or group of floral structures in a grass.
Spur-a hollow appendage on a flower.
Stolon-a creeping stem along the surface of the ground.
Succulent-fleshy and juicy.
Taproot-a thick, central root with minimal branching.
Trifoliate leaf-a leaf made of 3 leaflets; clover-like.
Whorled-3 or more similar structured arranged as spokes on a wheel.

© 1999 University of Idaho: Text and photographs for these pages from Idaho's Noxious Weeds, by Robert H. Callihan and Timothy W. Miller (revised by Don W. Morishita and Larry W. Lass).

Please contact: Ag Publishing, University of Idaho, Moscow, Idaho 83844-2240; 208 882-7982; cking@uidaho.edu; or visit the Resources for Idaho website at http://info.ag.uidaho.edu, for more information about this or other publications.