Department of Soil&Crop Sciences

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Grassy Weeds

Proper recognition and identification of turfgrass species is a critical skill that turfgrass managers must possess and continually improve upon. Turfgrass management uses cultural systems and pesticides that depend on the turf, pest and environmental conditions. Incorrect diagnosis of turfgrasses and pests can result in turf damage, and monetary losses. Turfgrass identification depends heavily on the vegetative characteristics of the plant. Additional clues used in identification are time of year, cutting height, soil moisture, and shade. Vegetative identification of grasses requires careful inspection of primary vegetative characteristics.

The vegetative keys are based primarily on the vernation, ligule, auricle, collar, and sheath. Recognition of these structures is essential for successful grassy weed identification.

Vernation.The arrangement of the leaves of the budleaf (youngest leaf) and the surrounding sheath. A folded vernation has the leaves folded in a V-shape with the margins meeting, but not overlapping. A rolled vernation has the leaves curled such that the margins are overlapping.

Ligule.A protruding structure from the upper surface of the leaf where the blade and the sheath are joined. This structure may be membranous, a fringe of hairs, or a membrane with hairs. The ligule can vary in both shape and size, and may also be absent.

Auricle.A pair of appendages protruding from the side of the grass leaf at the junction of the blade and the sheath. Auricles may be blunt, large and claw-like and have short hairs attached, or be absent.

Sheath.The basal portion of the grass leaf between the crown and the blade. The sheath margins may be split, split with overlapping margins, or be closed.

Collar.The region on the back side of a leaf where the leaf blade and sheath are joined. Collars may be divided by the midrib or be continuous. Collar shapes vary from broad to narrow and may have straight or slanted borders.

Blade.The portion of the leaf, which is divided from the sheath by the collar and ligule. The length, width, type of tip, and roughness or smoothness are a few of the characteristics of various species.

Rhizomes.An underground stem that produces a new plant. Rhizomes are present or absent, strong or weak.

Stolons.A horizontal, above ground stem that takes root at nodes and gives rise to new plants.

Seedhead The collection of flowering or seeding parts which are arranged in various ways (spike, panicle, etc.)

Examples of Seedheads.Seedheads