Achnatherum swallenii (C.L. Hitchc. & Spellenb.) Barkworth
Annotated by E. Poor, 11 Dec 2007. Sources: Flora of PNW.

Idaho: Custer County: About 12 mi. n.w. of Mackay on hiway, alt. 93, 1.8 mi. s. of Elkhorn Creek.
T8N R22E S2
Datum: NAD 27. Uncertainty: 800 meters. Coordinate Source: TRS2LL.
Growing on alluvial fan of rocky calcareous soil; with Astragalus calycosus, Sitanion hystrix, Poa gracillima, Agropyron spicatum, Artemisia frigida, Lesquerella alpina var. laevis, Phlox muscoides, Musineon divaricatum, Artemisia tridentata, Opuntia polycantha, Coryphantha missouriensis, Oryzopsis hymenoides. Plants forming dense tufts to about 20 cm. across. On live plants, a slight pull disarticulates the awn from the lemma. Mature fruits collected from plants grown outdoors at Seattle are as follows: body about 3.5 mm. long, 1 mm. broad; lemma gray-brown with silvery appressed pubescence; margins of the lemma .3-.5 mm. apart, exposing the palea, extending a two whitish, nearly hyaline, acute lobes almost .5 mm. long past the base of the awn; awn once geniculate, the bend in the lower 1/3. Plants in this population had chromosome complements of N=17II, 2N=34. Phenology: Fertile.

R. Spellenberg 1731, June 14, 1967
ID, Accession: 54910, Barcode: ID022237