Plants : perennial; cespitose, not rhizomatous. Culms: (35)50-150 cm tall, to 5 mm thick near the base, stiffly erect, not rooting at the lower nodes; internodes glabrous. Sheaths: longer than the internodes, smooth or scabridulous, rounded dorsally, bases somewhat flat and chartaceous; Ligules: 0.5-2(3) mm, firm, truncate, usually ciliolate; Blades: 10-50 cm long, 1.5-6 mm wide, flat or involute, stiff, glabrous abaxially, scabrous adaxially. Panicles : 15-60 cm long, 0.5-1.2 cm wide, spikelike, dense, grayish-green, often interrupted below; primary branches 0.2-4 cm, appressed; pedicels 0.2-3 mm, hispidulous, strongly divergent. Spikelets : 2.4-4 mm. Glumes subequal, 1.8-3.2 mm, almost as long as the florets, scabrous to scabridulous, 1-veined, usually acute or obtuse, occasionally acuminate or notched, occasionally mucronate, mucros to 0.6 mm; lemmas 2.4-4 mm, lanceolate, pubescent on the calluses, lower 1/6 of the margins, and midveins, hairs to 0.4 mm, apices scabrous, acute or obtuse, unawned, rarely mucronate, mucros to 1 mm; paleas 2.3-3.8 mm, lanceolate, acute; anthers 1.3-1.8 mm, yellow to purple. Caryopses : 1.8-2.2 mm, fusiform, brownish. 2n = 40.

Muhlenbergia rigens grows in sandy washes, gravelly canyon bottoms, rocky drainages, and moist, sandy slopes, often along small streams, at elevations of 90-2500 m. Its geographic range extends to central Mexico. It is available commercially as an ornamental.

Muhlenbergia rigens is similar to M. dubia, but differs in having tighter, spikelike panicles, shorter ligules, yellow or purplish anthers, and shorter lemmas, but differs in having tighter, spikelike panicles, shorter ligules, yellow or purplish anthers, and shorter lemmas.

FNA 2003

Common Name: deergrass Duration: Perennial Nativity: Native Lifeform: Graminoid General: Stiffly erect perennial bunchgrass with densely clumped stems from a hard knotty base, 60-150 cm tall. Vegetative: Blades firm, grayish, usually margins rolled upward, 10-50 cm long, tapering to a tip; sheaths rounded, flat with age; ligule thin and translucent, truncate, with slight lobes on either side, 0.5-2 mm long. Inflorescence: Dense spike, 15-60 cm long, rarely more than 1 cm thick; glumes subequal, lance-shaped, rough-textured, tapering to a pointed tip or tipped with an abrupt, sharp point (mucronate), half to nearly as long as lemma; lemma 2.5-4 mm long, inconspicuously nerved, slightly pilose on callus, tapers to a pointed tip, occasionally mucronate. Ecology: Found in gravelly or sandy canyon bottoms or washes, often in moist soil, less frequently on dry plateaus and meadows; 3,000-8,500 ft (914-2286 m); flowers July-October. Distribution: CA, NV, AZ, NM, w TX; south to s MEX. Notes: Muhlenbergia is a large and diverse genus primarily distinguished by having single-flowered spikelets with unequal glumes. M. rigens is a large, robust perennial bunchgrass with long rolled blades and an erect, long, narrow, spicate inflorescence with dense, single-flowered spikelets that are awnless. It is quite conspicuous in washes and canyons. Ethnobotany: Seeds were ground and eaten as a mush, made into cakes and bread, used as a forage, and used in basketmaking and other weavings, also used ceremonially. Etymology: Muhlenbergia is named for Gotthilf Heinrich Ernst Muhlenberg (1753-1815) a clergyman and botanist from Pennsylvania; while rigens is Latin word for stiff. Synonyms: Epicampes rigens, Muhlenbergia marshii, M. mundula Editor: SBuckley 2010, FSCoburn 2014, AHazelton 2015