General Description: A coarse-textured perennial producing spreading clumps and short, thick rhizomes. The center of the clump is often devoid of green leaves.
Seedling: Leaves are narrow and rolled in the bud. Ligule is tall and membranous with a rounded or bluntly pointed tip. Auricles are absent. Blades of the first leaves may be softly hairy, but most lack hairs except for long silky hairs at the collar. Sheaths are flattened with a prominent midrib. Those of the first leaves are softly hairy and persist through the growing season. Later leaves have smooth sheaths. Mature Plant: Robust plants, with prostrate or ascending leaves arising from tillers and short, shallow rhizomes. Most vegetative characteristics are similar to those of seedling plants. Mature leaf blades are flat, 4 to 12 in (10 to 30 cm) long by 1/4 to 1/2 in (6 to 15 mm) wide, and lack hairs, except for a few long hairs at the collar. Leaf margins are finely hairy and rough. Sheaths lack hairs (except for the few, older leaves), are strongly compressed, with a prominent midvein, and may be tinged red with age. The collar is broad, light green, smooth, often with long hairs at the edges. Tillers are stout and do not root at the nodes. Flowers and Fruit: Plants flower from midsummer to early fall. Flowers and seeds are produced on a rachis in a raceme that bears 3 to 5 spreading or loosely ascending spike-like branches 2 to 4 in (5 to 10 cm) long. The spikelets are ovate, 1/8 to 1/6 in (3 to 4mm) long and 1/13 to 1/10 in (2 to 2.5 mm) wide, hairy, and crowded in 4 rows on the racemes. Spikelets are covered with silky soft hairs. Seeds are oval, shiny, yellow to brown. Distribution: Widely distributed in the across the United States Crops Affected: Turf, Pastures, Roadsides, and No-till Corn, Soybean, Wheat Animal Poisoning: None Similar Species: Dallisgrass seedlings strongly resemble large crabgrass, with hairy leaves, rolled leaf buds, and membraneous ligules; however, dallisgrass has rhizomes, and the leaves of more mature plants lack hairs, whereas, large crabgrass leaves remain hairy. Knotgrass is similarly coarse-textured perennial, but with a stoloniferous habit, shorter leaves, and fewer racemes (2), on stalks arising from leaf axils.