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 UI Extension/CALS Publications and Multimedia Catalog website at www.cals.uidaho.edu/edComm/catalog.asp, for more information about this or other publications.
