3. Bouteloua hirsuta Lag. var. hirsuta (hairy grama)

Pl. 142 c–e; Map 574

Chondrosum hirsutum (Lag.) Sweet

Plants without rhizomes, forming dense clumps. Flowering stems 10–40(–60) cm long, erect or ascending. Leaf sheaths glabrous or roughened to sparsely hairy, especially near the tip. Leaf blades 1–15(–20) cm long, 1–3 mm wide, flat, sparsely pubescent on the margins and sometimes also the surfaces near the base with short, pustular‑based hairs, sometimes also roughened. Inflorescence relatively short, with 1–3 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 15–35 mm long, with 20–60 spikelets, the axis of the spike straight or more commonly somewhat curled upward at maturity, extended 4–10 mm past the uppermost spikelet as a stiff, hairlike projection. Lower glume 1.5–3.5 mm long, linear or awnlike, glabrous or roughened. Upper glume 3–5 mm long, narrowly lanceolate, densely pubescent along the midnerve with pustular‑based hairs. Fertile lemma 2.0–4.5 mm long, lanceolate, hairy, the nerves extended into short awns 0.5–1.5 mm long at the tip. Sterile lemma with the body 0.5–2.0 mm long, the nerves extended into awns 2–4 mm long. Anthers 2.0–2.5 mm long, yellow or less commonly greenish yellow. Fruits 1.5–2.0 mm long. 2n=12–50, mostly 2n=20, 40, 60. July–September.

Uncommon in the Glaciated Plains Division in northwesternmost Missouri and known from a single historical collection from Clark County (western U.S. east to Wisconsin and Louisiana, introduced sporadically further east; Canada, Mexico). Loess hill prairies and sand prairies.

A second variety, var. glandulosa (Cerv.) Gould, occurs from Arizona south to Guatemala, and differs from var. hirsuta in having the flowering stems hairy below the nodes. A closely related species endemic to portions of Oklahoma and Texas, B. pectinata Feath., sometimes also is treated as a variety of B. hirsuta (var. pectinata (Feath.) Cory), and differs in having a dense tuft of hairs at the base of the sterile lemmas.

Hairy grama is very uncommon in Missouri and presently is known from a single extant site in Atchison County.