Plants with C₄ photosynthesis, annual or perennial, without noticeable rhizomes, forming tufts or clumps. Flowering stems erect or ascending, usually branched, sometimes only near the base. Leaf sheaths open most of their length, the ligule a fringe of short hairs, sometimes from a minute, membranous base. Leaf blades narrow, often inrolled. Inflorescences narrow panicles or spikelike racemes (broad panicles with spreading branches elsewhere). Spikelets with 1 fertile floret, disarticulating above the glumes. Glumes 2, the lower occasionally shed early, papery, linear to narrowly lanceolate, with 1, 3, or 5 nerves, often with an awn, in species with multiple nerves the upper glume also with 2 soft lateral awns. Lemmas hardened, linear, wrapped around the palea and fruit, rounded on the back, 3‑nerved, yellowish green or more commonly green mottled with purple, the tip tapered to 3 awns, these sometimes united into a column at the base, the lateral awns sometimes reduced and much shorter than the central awn. Paleas much shorter than the lemmas, usually 2‑nerved, lacking awns. Stamens (1)3. Fruits linear, shed inside the persistent lemmas. About 250 species, worldwide, but most abundant in tropical and warm‑temperate regions.

Although the long, often bent or twisted awns of Aristida species aid in dispersal of the fruits in animal fur or botanists’ socks, they render these grasses relatively uninteresting as forage to livestock and other grazers, which can receive injuries to the noses, eyes, mouths, and intestines when attempting to graze on them.