P, by assignment. Diploids and tetraploids are known.
Perennial with solitary spikelets. Glumes are strongly keeled throughout. In many species, the middle internodes of the inflorescence are less than one third as long as the adjacent spikelets.
Plants perennial, not or only shortly rhizomatous. Culms 25-110 cm tall, geniculate or erect; lowest internode 1-2 mm thick.
Leaf blades 1.5–9 mm wide, flat, folded, or convolute, upper surface with 8–12 prominent ribs.
Inflorescence spikelike, stiff; rachis tough, with solitary spikelets; lowest internode subequal to much several times longer than the middle internodes; middle internodes 1-5 mm, often less than one third as long as the adjacent spikelets.
Spikelets solitary, tangential to the rachis, sessile, sometimes strongly divergent; lowest spikelet longer than the adjacent internode, sometimes many times longer; middle spikelets from almost twice as long as the adjacent internode to many times longer.
Glumes shorter than the adjacent lemmas, strongly keeled from the base to the tip, glabrous or hairy, not scabrous, acuminate.
Lemmas often keeled from base to tip, not or shortly awned. Paleas not winged, tapering with straight sides to a narrow tip, the keel veins often extending beyong the intercostal region. Lodicules lobed, ciliate. Anthers 0.4-5 mm.
About 10 species, with approximately 20 infraspecific taxa. For listing, see http://herbarium.usu.edu/triticeae/agropyron.html
Native to Western and Central Asia. Some species have become established in other parts of the world after being introduced for soil stabilization.
Agropyron used to be interpreted as including all the perennial Triticeae with solitary spikelets and tough rachises. That interpretation has now been universially rejected and the sense used here universally accepted. The genus was recognized as such before it was appreciated that all its members were diploids or tetraploids based on the P genome.
Agropyron cristatum (L.) Gaertn.
All work on Agropyron so far has either been traditional in its approach - which is fine as far as it goes, but we can go farther nowadays - or it has been conducted on accessions in genebanks which have often been grown and multiplied under conditions that permit hybridization. The genetic basis and relationships among its taxa needs to be evaluated.
Asay, K.H., K.B. Jensen, C. Hsiao, and D. R. Dewey. 1992. Probable origin of standard crested wheatgrass, Agropyron desertorum Fisch. ex Link, Schultes. Can. J. Plant Sci. 72: 763-772.