63. Echinochloa P. Beauv. (barnyard grass)

(Gould et al., 1972)

Plants with C₄ photosynthesis, annual (perennial elsewhere), forming tufts or small clumps. Flowering stems usually spreading in the basal portion and sometimes rooting at the lower nodes, otherwise erect to spreading, circular in cross‑section or slightly flattened, glabrous or rarely sparsely hairy at the nodes. Leaf sheaths glabrous or hairy, somewhat flattened and keeled, the ligule absent (a line of hairs elsewhere). Leaf blades flat, glabrous or hairy, the base rounded or abruptly narrowed, the midvein conspicuous and thickened on the undersurface. Inflorescences panicles with the primary branches unbranched or with several short secondary branches, the branches consisting of somewhat or strongly 1‑sided, spikelike racemes, these with a spikelet at the tip. Spikelets solitary or paired along the axis, not subtended by bristles or spines, disarticulating below the glumes, without a cuplike ring or knoblike disk at the base. Lower glume up to about 1/2 as long as the rest of the spikelet, broadly ovate, pointed at the tip, awnless, 3‑nerved, glabrous or hairy. Upper glume about as long as the rest of the spikelet, elliptic to ovate, not inflated, sometimes tapered to an awn at the tip, 5‑nerved. Lowermost floret sterile, the palea well developed (absent or highly reduced in E. crus‑pavonis), the lemma about as long as the rest of the spikelet, elliptic to ovate, sometimes tapered to an awn at the tip, 5‑nerved. Fertile floret with the lemma elliptic to elliptic‑ovate, abruptly contracted to a short, often wrinkled, sharp, awnlike point at the tip, this differentiated from the body of the lemma by a usually green band, nerveless or obscurely nerved, glabrous, smooth, usually shiny, light yellow to straw‑colored or grayish white, thickened and relatively hard (usually somewhat bonelike) at maturity, the margins not thinner or lighter colored, noticeably wrapped around the palea, but not enclosing its free tip. Paleas glabrous, slightly shorter than and similar in texture to the lemma. Fruits broadly elliptic to ovate in outline. About 40 species, nearly worldwide, mostly in tropical and warm‑temperate regions.