Muhlenbergia racemosa (Michx.) Britton, Sterns, & Puggenb.

Green muhly

Poaceae (Grass family)

General Description: A stiffly erect perennial grass, 25-100 cm tall, from long, creeping, scaly rhizomes. The flat leaf blades are more or less evenly distributed along the culm and 5-15 cm long by 2-7 mm broad. Internodes are glabrous. The membranous ligules are up to about 1.5 mm long. The inflorescence is a narrow, spike-like panicle 4-17 cm long with densely clustered, light green, 1-flowered spikelets. The subequal glumes are 3-7 mm long and taper into a short awn. Lemmas are 2-4 mm long, pubescent along the lower half, and either awnless or with a short awn tip. Anthers are small, up to 0.8 mm long.

Illustration.

Field Identification Tips: The relatively tall, rhizomatous habit, spike-like inflorescence, 1-flowered, light green-colored spikelets, and short-awned glumes are useful field characteristics. Positive identification requires using a technical key and measuring technical morphological characteristics.

Phenology: Flowers July to September.

Similar Species: Several perennial Muhlenbergia species with spike-like inflorescences that occur in moist habitats could be confused with M. racemosa. Muhlenbergia glomerata (marsh muhly) closely resembles M. racemosa, and the two have been merged in some treatments. Muhlenbergia glomerata differs in its finely puberulent internodes, shorter ligules (0.2-0.6 mm), and slightly longer anthers (about 1 mm long). In addition, M. glomerata typically occupies wetter habitats such as streambanks, wet meadows, and lakeshores. Muhlenbergia andina (foxtail muhly) differs in a number of technical characters. The easiest one to see in the field is the dense, silky callus hairs about as long as the lemma. Muhlenbergia mexicana (Mexican muhly) has puberulent internodes, shorter glumes (up to about 3.5 mm long), and slightly spreading branches in the inflorescence.

Habitat: Drying meadows, rocky slopes, along irrigation ditches, and often in cultivated and other disturbed sites.

Global Distribution: Alberta to Ontario, south throughout much of the United States, except for the southeast and parts of the northeast. Uncommon in the Intermountain Region.

Idaho Distribution: The disposition of several Idaho populations is unresolved. Reports of this species are known from Bonner and Boundary counties in northern Idaho, and Bannock, Caribou, Fremont, and Teton counties in the eastern part of the state.

References:

Cronquist, A., A. H. Holmgren, N. L. Holmgren, J. Reveal, and P. K. Holmgren. 1977. Intermountain Flora. Vascular plants of the Intermountain West, U.S.A. Vol. 6. Published for The New York Botanical Garden by Columbia University Press, NY. 584 pp.