Genomic constitution

StHNN, the St genome being from Pseudoroegneria, the H genome from wild barley (Hordeum), and the N genome from Leymus.

Distinguishing features

Rhizomatous perennial species with solitary spikelets and glumes that are stiff, narrow from near the base, and "lean sideways".

Description

Plants perennial, rhizomatous. Culms 20-100 cm tall, glabrous.

Leaf blades 1-5 mm wide, folded to loosely involute, often glaucous.

Inflorescence spikelike, 5-17 cm long; rachis touch, terminating in a spikelet; middle internodes 4.5-11 mm long; disarticulation below the florets.

Spikelets 12-30 mm long, with 2-12 florets, 1-3 times as long as the adjacent internode, usually solitary, sometimes 2 at the lower nodes, solitary spikelets tangential to the rachis.

Glumes 5-15 mm long, tapering from at or below midlength to an acuminate tip, appearing 1-veined distally, the vein curving sideways distally. Lemmas 6-14 mm long, acute or mucronate to awned, awns to 5 mm. Paleas slightly shorter than the lemmas. Lodicules. Anthers 4-5 mm long.

Size

There is only one species in the genus, Pascopyrum smithii.

Distribution

Pascopyrum is restricted to North America.

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Alternative interpretations

Pascopyrum is sometimes included in Elymus, sometimes in Elytrigia.

Type species

Pascopyrum smithii (Rydb.) Barkworth & D.R. Dewey

Known problems

No particular problems. It is often difficult to distinguish Pascopyrum smithii from Elymus lanceolatus and Leymus triticoides. It differs from Elymus lanceolatus in having glumes that narrower from midlength or below and lean sideways distally and in tending to have a shorter and wide first rachilla segement, their length width ratio being 1.8 versus 2.6 in Elymus lanceolatus.

References

Flora of North America, vol. 24.
Barkworth, M.E., J.J.N. Campbell, and B. Salomon. 2007. Elymus, pp. 288-343 in M.E. Barkworth, K.M.C. Capels, S. Long. L.K. Anderton, and M. Piep (Eds), Flora of North America, vol. 24. Oxford University Press, New York, United States.