Weed Glossary

Grass-weeds

Leaf blade:  The free part of the grass leaf 1  6.

Leaf sheath:  The part of the grass leaf that grasps the stem 2  6.

Awn:  A bristle arising from the outer covering of the seed of a grass 3.

Rhizome: An underground stem that runs horizontally 4.

Stolon: A stem that runs horizontally on the soil surface 5.

Auricles

Ligule: Membranous extension at the junction of the leaf sheath and blade 6.

Boat-shaped tip: Characteristic of Poa spp 7

Tramlines: Two parallel lines, one either side of the mid-rib. Easily seen if held up to the light. Characteristic of Poa spp 8.

Ribbed leaf9

Non-ribbed leaf10

Rolled in bud:  Characteristic of Italian rye-grass11.

Folded in bud:  Characteristic of Perennial rye-grass12.

Spikelet: A small spike or branch-like part, usually referring to the spike supporting the arrangement of blossoms on grasses.

Panicle: The compound flowering head or ear of a grass in which each spikelet has a distinct stalk attached to the main stem.

Inflorescence: Compound flower head - there are three main types:

  • Spike-type inflorescence - each spikelet has no individual stalk but is borne directly on the main stalk e.g. black-grass, rye-grasses and couch13.
  • Lobed inflorescence - each panicle has large spikelets e.g. bromes and Cock'sfoot 14.
  • Spreading inflorescence - each panicle has many small spikelets e.g. meadow-grasses, Yorkshire fog and bent grasses 15.

Broad-leaved weeds

Annual: A plant that completes its lifecycle, from germination to death, within one year.

Calyx: The outermost part of the flower.

Cotyledon(s): The first leaves sent out by the germinating seed - the seed leaves.

Entire:  Describes leaves with an even margin.

Node(s):  The point on a stem from which a leaf arises.

Notch: An indentation or cut out.

Perennial: A plant that lives for more than two years and usually flowers annually.

Prostrate: Lying on the surface of the soil.

Rosette: A cluster of leaves in a circular form on the soil.

True leaves: The later leaves of a seedling developing after the cotyledons(s).

Umbellifer: A plant bearing flat-topped or rounded flower clusters

Whorl: Three or more leaves arising at the same node.