Plants hermaphroditic, caespitose, annual or perennial. Culms erect or ascending; internodes solid, glabrous, slightly
flattened; nodes glabrous. Leaves basal and cauline, not distinctly distichous; sheaths with compressed keels, margins open;
auricles absent; ligules a ciliate membrane; blades flat or folded, linear, lax, apex obtuse to acute. Spicate racemes
terminal (occasionally axillary inflorescences per culm), not aromatic; rachis hairy; pedicels not having a longitudinal
groove, hairy, semi-terete. Spikelets paired at each inflorescence node, dissimilar is size and shape, (pedicellate
spikelets larger), disarticulation below the glumes, dorsiventrally compressed, sessile (or short pediceled) spikelets fertile,
pedicellate (or long pediceled) spikelets staminate or neuter. Pedicellate spikelets well developed but usually
staminate, awnless. Sessile spikelets perfect; first glumes 0-keeled, gland-like depressions or pits not present;
abaxial surface convex, smooth, coriaceous, hairy, awnless; second glumes length equal to the first glumes; lower floret
sterile; lemmas hyaline (3-veined), entire, awnless; paleas absent; upper florets perfect, lemmas (3-veined)
cartilaginous below, entire, awned from apex, awns 1-geniculate and dark brown; paleas present, or absent, (reduced
when present). Stamens 0 or 1 or 2 or 3; anthers brown. Caryopses dorsiventrally compressed, longitudinally grooved. Base
chromosome number x=10.
A genus of about seven species that occur in tropical and subtropical regions of the world. Tanglehead (H.
contortus) has a worldwide distribution and is a important forage in the southwestern United States.