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;  ; or visit the Resources for Idaho website at  , for more information about this or other publications.