Poaceae

Agropyron

Intermountain Flora, v. 6, p. 318

• 1. Spikelets spreading from the axis of the spike, much compressed and crowded, the rachis internodes only 0.3-2.2-(3) mm long in the middle of the spike. Agropyron
• 1.1. Spikelets divaricate at broad angles, giving the spike an oblong-oval, flat shape, the spikelets crowded, separated by short rachis internodes (0.7)-1-1.9-(2.3) mm long.
• 1.2. Spikes subglabrous to grabrate; glumes scabrous only on the keel. Agropyron cristatum ssp. pectinatum = Agropyron pectiniforme

Agropyron cristatum	Agropyron cristatum

• 1.2' Spikes densely hairy. Agropyron cristatum ssp. cristatum
• 1.1' Spikelets more ascending, giving the spike a narrow-oblong subcylindrical shape, the spikelets separated by longer rachis internodes (1.5)-2.5-3.5-(5) mm long. Agropyron desertorum = Agropyron cristatum ssp. desertorum
• 1' Spikelets apressed to the rachis of the spike, the rachis internodes (2.5)-4-25 mm long in the middle of the spike (the short internodes found in A. scribneri and x Agrositanion saundersii).
• 2. Plants with long, creeping rhizomes.
• 3. Lemmas awnless or merely awn-tipped with awns no more than 5 mm long (upto 10 mm in some A. repens) and straight.
• 4. Glumes and lemmas obtuse or rounded to acute, if awned the awn arising from a minutely bifid apex; blades usually lax and flat; plants usually green, rarely glaucous.
• 5. Glumes and lemmas obtuse to rounded. Thinopyrum intermedium = Agropyron intermedium

Thinopyrum intermedium	Thinopyrum intermedium

• 5' Glumes acute.
• 6. Glumes about 1/2 the length of the spikelet. Elymus repens = Agropyron repens

Elymus repens	Elymus repens	Elymus repens

• 6' Glumes 2/3 to nearly equaling the spikelet. Elymus X pseudorepens = Agropyron pseudorepens
• 4' Glumes acute to acuminate, gradually tapering into a point or awn tip; lemmas acute; blades firm, stiff, mostly involute; plants usually glaucous.
• 7. Glumes narrow-lanceolate, acuminate, tapering from below the middle into an awn tip. Pascopyrum smithii = Agropyron smithii

Pascopyrum smithii	Pascopyrum smithii	Pascopyrum smithii

• 7' Glumes oblong lanceolate, acute to acuminate, broadest at or above the middle. Elymus lanceolatus = Agropyron dasystachyum
• 7'1. Lemmas scabrous to villous; plants of dry, usually sandy soils. Elymus lanceolatus ssp. lanceolatus = Agropyron dasystachyum var. dasystachyum

Elymus lanceolatus ssp. lanceolatus	Elymus lanceolatus ssp. lanceolatus	Elymus lanceolatus ssp. lanceolatus

• 7'1' Lemmas glabrous to scaberulous; plants of more mesic habitats, usually in heavy soils. Elymus lanceolatus ssp. riparius = Agropyron dasystachyum var. riparium
• 3' Lemmas with awns 5 mm or more long, the awns divergent at maturity; Rich, Summit, Wasatch, Uintah counties. Elymus albicans = Agropyron albicans

Elymus albicans	Elymus albicans

• 2' Plants without creeping rhizomes (occasionally short rhizomes present in A. spicatum and A. trachycaulum).
• 8. Rachis continuous; glumes awnless or shortly awn-tipped.
• 9. Glumes no more than half as long as the spikelet; anthers 4-6 mm long; internodes of the rachis 9-25 mm long.
• 10. Lemmas awnless; glumes thick, indurate, obtuse to truncate. Thinopyrum elongatum = Thinopyrum ponticum = Agropyron elongatum

Thinopyrum elongatum	Thinopyrum elongatum

• 10' Lemmas usually distinctly awned with awns up to 25 mm long; glumes not thick or indurate, acute to acuminate, sometimes obtuse; (two vars: var. spicatum: lemma awned and var. inerme: lemma awnless or nearly awnless). Pseudoroegneria spicata = Agropyron spicatum

Pseudoroegneria spicata	Pseudoroegneria spicata	Pseudoroegneria spicata

• 9' Glumes 2/3 to nearly as long as the spikelet; anthers small, 1-1.8-(2) mm long; internodes of the rachis 4-8-(11) mm long. Elymus trachycaulus = Agropyron trachycaulum

Elymus trachycaulus	Elymus trachycaulus

• 8' Rachis tardily disarticulating; glumes long-awned.
• 11. Culms prostrate-spreading, or at least decumbent at the base, mostly less than 3 dm tall; fertile subalpine or alpine species. Elymus scribneri = Agropyron scribneri

Elymus scribneri	Elymus scribneri

• 11' Culms erect, mostly more than 4 dm tall; steryle hybrids of low to midmontane elevations.
• 12. Awns of the lemma long and spreading, often recurved, mostly (14)-18-37 mm long; internodes of the rachis mostly 7-10 mm long. X Agropyron saxicola
• 12' Awns of the lemma shorter, 4-17-(35) mm long; if very long, straight; internodes of the rachis mostly 2.5-6-(7) mm long. X Agropyron saundersii