3. Bothriochloa Kuntze (bluestem)

Plants perennial, forming clumps. Flowering stems erect, sometimes highly branched above the basal portion, with a longitudinal groove. Leaf sheaths glabrous, often somewhat glaucous, mostly rounded on the back, the ligule membranous, the margin becoming irregular or torn with age. Leaf blades linear, not rounded or heart‑shaped at the base, flat or sometimes folded at maturity, often somewhat glaucous. Inflorescences sometimes partly enclosed by the subtending leaf sheaths, dense panicles with the branches spikelike racemes (reduced to nearly palmate clusters elsewhere), the lowermost branches sometimes rebranched. Individual racemes with the axis and spikelet stalks hairy, breaking apart into joints (as a unit with the associated spikelets) at maturity, the spikelets paired at the nodes. Stalked spikelet staminate or sterile, when sterile then reduced in size, the stalk strongly grooved on both sides, the grooved portion thin and easily ruptured. Sessile spikelet with the perfect, upper floret subtended by a sterile floret, this reduced to a membranous lemma lacking an awn. Glumes of sessile spikelet longer than the florets, the lower glume strongly 2‑nerved, the upper glume strongly 1‑nerved. Fertile lemma membranous, narrowly ovate, the thickened midnerve extended into a long awn. Palea reduced or absent. Fruits 2–3 mm long. About 35 species, nearly worldwide, but most diverse in tropical and warm‑temperate regions.