Muhlenbergia pectinata
Plants annual. Culms 10-33 cm, erect or decumbent, sometimes rooting at the lower nodes; internodes glabrous. Sheaths usually longer than the internodes, glabrous, margins sparsely hairy distally, hairs to 1 mm, coarse; ligules 0.3-0.9 mm, membranous, truncate, ciliate; blades 1-6 cm long, 0.6-2 mm wide, flat to loosely involute, appressed-pubescent to sparsely pilose. Panicles 4-12 cm long, 0.5-2.6(4) cm wide; primary branches 2-3.5 cm, appressed or diverging up to 70° from the rachises; pedicels 1-3 mm, glabrous, appressed; disarticulation above the glumes. Spikelets 2.5-5 mm, borne singly. Glumes glabrous, 1-veined, acute to acuminate, unawned or awned, awns to 1.5 mm; lower glumes 0.8-1.7 mm, entire; upper glumes 1-2(3) mm; lemmas (2.5)3-4.5(5) mm, subulate to lanceolate, calluses appressed-pubescent, lemma bodies appearing 5-veined (the intermediate "veins" are actually rows of short barbs on top of folded epidermal ridges), lateral veins occasionally ciliate, apices acuminate, awned, awns 10-32 mm, slender, flexuous; paleas 2.4-4.4 mm, narrowly lanceolate, glabrous, acuminate; anthers 0.3-0.6 mm, yellowish. Caryopses 0.6-3.1 mm, narrowly fusiform, light brownish. 2n = 20.
Discussion
Muhlenbergia pectinata grows on rock outcrops, rocky cliffs, canyon walls, steep slopes, and road cuts, at elevations of 45-2400 m in thorn-scrub forests, gramma grasslands, and pine-oak woodlands. It is almost entirely restricted to vertical surfaces that are seasonally wet. Its range extends from southeastern Arizona to Oaxaca, Mexico.
Selected References
None.