Achnatherum swallenii (C.L. Hitchc. & Spellenb.) Barkworth

Idaho: Custer: About 12 mi. n.w. of Mackay on hiway, alt. 93, 1.8 mi. s. of Elkhorn Creek.
44.038649° N, 113.82861° W,
Growing on alluvial fan of rocky calcareous soil. Associated taxa: 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. HerbariumSpecimenDuplicate: Achnatherum swallenii | herbariumSpecimenDuplicate: Oryzopsis swallenii | herbariumSpecimenDuplicate: Achnatherum swallenii | herbariumSpecimenDuplicate: Achnatherum swallenii | herbariumSpecimenDuplicate: Achnatherum swallenii 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 0.3-0.5 mm apart, exposing the palea, ext ending a two whitish, nearly hyaline acute lobes almost 0.5 mm. long past the base of the awn, awn once geniculte, the bend in the lower 1/3. Plants in this population had chromosome complements of N=17 II, 2N=34; growing on alluvial fan of rocky calcareous soil. Https://intermountainbiota.org/portal/collections/individual/index.php?occid=30810850.

R. Spellenberg 1731, 1967-6-14
WS, Catalog: 261141