Wisconsin State Herbarium Photo Photographer: Emmet J. Judziewicz CLICK PHOTO FOR A LARGER IMAGE

Nassella viridula (Trin.) Barkworth

Green needlegrass

Poaceae (Grass family)

Synonym: Stipa viridula Trin.

General Description: A tufted perennial bunchgrass 50-100 cm tall, with mainly basal leaves having curled margins, and often thread-like towards the tip. The upper leaves are sometimes flat, with blades 3-6 mm broad and usually between 10-30 cm long. The ligule is a smooth or hairy membrane up to about 3 mm long. The inflorescence is a narrow greenish panicle with erect branches, and 10-25 cm long. Spikelets are one-flowered, with membranous glumes tapering to a sharp tip, 8-13 mm long, and with 3 prominent green veins. Lemmas are cylindrical, brown, leathery, evenly soft hairy, 5-6.5 mm long, with a short, blunt white-bearded base (callus), and twice bent awn 25-35 mm long. The palea is less than half as long as the lemma and hairless.

Illustration.

Field Identification Tips: Green needlegrass is recognized by its tall, tufted habit, relatively narrow and curled leaves, narrow panicle, hairy, leathery lemma with a twice bent awn, and tiny, hairless palea.

Phenology: Flowers June and July

Similar Species: Green needlegrass is most likely to be confused with some species of Achnatherum (Stipa in part), especially those in the A. occidentale and A. nelsonii complexes, A. pinetorum, and A. lettermanii. These species are distinguished from green needlegrass on technical differences in the awn, callus, and margins of the lemma, the size of the palea, and other small features not always easy to determine in the field. Most tend to be shorter and have thinner leaves than green needlegrass.

Wisconsin State Herbarium Photo Photographer: Emmet J. Judziewicz CLICK PHOTO FOR A LARGER IMAGE

Habitat: Grasslands and sagebrush slopes and adapted to a wide range of soil textures. One Idaho population is on dry, rocky/gravelly volcanic soil with Artemisia tridentata, Leymus cinereus, Pseudoroegneria spicata, and Poa secunda.

Global Distribution: Southern British Columbia, Alberta, and Saskatchewan, southward through Montana, mostly east of the Continental Divide to Arizona and New Mexico, but also in Utah and Idaho, and throughout the Great Plains south to Kansas and east to Illinois. It has also been introduced in many parts of eastern North America.

Idaho Distribution: Idaho collections are from the foothills of the southern Beaverhead Mountains in Clark County, and from near Soda Springs in Caribou County.

References:

Hitchcock, A. S. 1950. Manual of the grasses of the United States. Second Edition revised by Agnes Chase. United States Department of Agriculture, Miscellaneous Publication No. 200. United States Government Printing Office, Washington, D.C. 1051 pp.

Spahr, R., L. Armstrong, D. Atwood, and M. Rath. 1991. Threatened, endangered, and sensitive species of the Intermountain Region. U.S. Forest Service, Intermountain Region, Ogden, UT.

U. S. Department of Agriculture, Forest Service. 1937. Range plant handbook. United States Government Printing Office, Washington, D.C.