Scientific Name
Achnatherum nelsonii (Scribn.) Barkworth ssp. nelsonii (Synonyms: Stipa nelsonii)
Common Name(s)
Columbia needlegrass, Nelson’s needlegrass
Tribe / Family Name
Stipeae
Flowering Period
June to August
Symbol
ACNEN2
Description
Columbia needlegrass is a native cool-season perennial bunchgrass that reproduces from seeds and tillers. Culms range from 40–175 cm in height. Its inflorescence is a narrow, compact or rather loose panicle 9–36 cm long with short, appressed branches, and numerous spikelets. Spikelets are appressed to the branches, 1-flowered, and awned (the lemma awns 19–45 mm long, twice geniculate, scabrous or with hairs <0.5 mm along the first two segments, and straight and glabrous to scaberulous along the terminal segment). Ligules are sometimes up to 2 mm long, membranous, truncate, erose, glabrous, occasionally higher on the sides, and decurrent.
General Info
This drought-tolerant and long-lived species can be found along roadsides, dry mountain meadows, sagebrush steppe, pinyon-juniper woodlands, foothills, and montane to subalpine sites.
Similar Species
Columbia needlegrass looks similar to other needlegrass (Achnatherum) species, especially Letterman’s needlegrass (Achnatherum lettermanii). Although both species have awns that are scabrous along the first two segments, they can be distinguished by their heights, leaves, inflorescences, and awns. Columbia needlegrass is usually a more robust plant with wider leaves, bigger inflorescences, and longer awns, and Letterman’s needlegrass is usually a less robust plant with narrower leaves, shorter inflorescences, and smaller awns. Also, Columbia needlegrass has apical hairs on the paleae that are generally not exceeding the apices, and Letterman’s needlegrass has apical hairs on the paleae that generally exceed the apices.
Picture of growth habit.
Close-up picture of narrow panicle inflorescence.
Close-up picture of spikelet.
Close-up picture of callus (bottom), hairy lemma (middle), and scabrous awn (top).
Close-up picture of subequal glumes.
Close-up picture of membranous ligule.
Illustration of Columbia needlegrass. USDA-NRCS PLANTS Database / Hitchcock, A.S. (rev. A. Chase). 1950. <i>Manual of the grasses of the United States</i>. USDA Miscellaneous Publication No. 200. Washington, DC.