Plants annual or perennial; cespitose. Culms (2)5-65 cm, herbaceous, usually rooting at the lower nodes; nodes and internodes glabrous. Leaves cauline; sheaths open, usually shorter than the internodes, mostly glabrous but long-ciliate at the edges of the collar; ligules membranous, truncate, ciliate; blades usually flat, margins ciliate. Inflorescences terminal, exceeding the upper leaves, narrow, cylindrical panicles; branches 0.5-5 mm, resembling burs, with 2-5 spikelets; disarticulation at the base of the branches. Spikelets crowded, attached individually to the branches, with 1 floret; proximal spikelet(s) bisexual, larger than the distal spikelet(s); terminal spikelets often sterile. Glumes unequal; lower glumes absent or minute, veinless, membranous; upper glumes usually exceeding the florets, 5-7-veined, with 5-7 longitudinal rows of straight or uncinate spinelike projections; lemmas 3-veined; paleas 2-veined, hyaline, membranous. x = 10. Name from the Greek tragos, he-goat.