2. Bouteloua gracilis (Kunth) Lag. ex Griffiths (blue grama)

Pl. 142 a, b; Map 573

Chondrosum gracile Kunth

Plants with rhizomes absent or short and stout, forming dense clumps. Flowering stems 15–30(–60) cm long, erect or ascending. Leaf sheaths glabrous or the lowermost sparsely hairy. Leaf blades 2–15 cm long, 1–2 mm wide, usually somewhat curled and with the margins inrolled, sparsely pubescent on the margins near the base with short, pustular‑based hairs and often roughened on the upper surface. Inflorescence relatively short, with 1–4 loosely spaced spikes, these spreading, the spike axis persistent, with spikelet disarticulation above the glumes, leaving the axis appearing chaffy or scaly after the florets have been shed. Spikes 14–40 mm long, with 20–60 spikelets, the axis of the spike straight or more commonly somewhat curled upward at maturity, not extended past the uppermost spikelet. Lower glume 1.5–3.5 mm long, linear or awnlike, glabrous or roughened. Upper glume 3.5–5.0 mm long, narrowly lanceolate, sparsely pubescent along the midnerve with pustular‑based hairs. Fertile lemma 3.5–5.0 mm long, lanceolate, hairy, especially toward the base, the nerves extended into short awns 0.5–1.5 mm long at the tip. Sterile lemma with the body 1–3 mm long, the nerves extended into awns 1–3 mm long. Anthers 1.5–3.0 mm long, yellow or less commonly greenish yellow. Fruits 2.5–3.0 mm long. 2n=20–84, mostly 2n=20, 40, 60. July–September.

Scattered in the Glaciated Plains Division in westernmost Missouri and introduced in St. Louis County (western U.S. east to Wisconsin and Arkansas, introduced sporadically farther east; Canada, Mexico; introduced in South America). Upland prairies, especially loess hill prairies; also railroads.

Blue grama is an important and widespread range grass in the Great Plains and western United States, where it is considered an excellent native forage species. However, it is too uncommon in Missouri to be considered important for grazing.