19. Alopecurus L. (foxtail)

Plants annual or perennial, forming tufts or small clumps. Flowering stems erect or ascending, sometimes from spreading bases, glabrous, darkened just below the nodes. Leaf sheaths rounded on the back, glabrous or roughened. Leaf blades flat, glabrous or usually roughened along the margins and on the upper surface. Inflorescences appearing as dense, cylindrical (or nearly so) spikes, the short branches appressed to but not fused with the main axis, not apparent at flowering time without dissecting the inflorescence. Spikelets strongly flattened laterally, disarticulating below the glumes, with 1 perfect floret and without additional staminate or sterile florets. Glumes about as long as the lemma, similar in size and shape, oblong to elliptic‑ovate, rounded to sharply pointed at the tip, awnless, usually fused toward the base, strongly keeled and 3‑nerved, hairy, at least on the midnerve (keel). Lemma thin and membranous, oblong‑elliptic, rounded to sharply pointed at the tip, with a short to long, slender awn attached at or below the midpoint of the back, faintly 3‑ or 5‑nerved, glabrous. Palea absent. Stamens 3. Fruits broadly elliptic in outline, yellow to olive or light brown. About 35 species, U.S., Canada, South America, Europe, Asia.

The awns on the lemmas of some Alopecurus species are easily overlooked. In order to see the attachment point of the awn, it is necessary to dissect the spikelet, because it is at or below the middle of the lemma and is hidden by the glumes.