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.