Plants perennial; cespitose, forming dense to loose clumps, sometimes stoloniferous, sometimes rhizomatous. Culms 15-120 cm, erect or decumbent. Basal sheaths closed, becoming somewhat fibrillose; ligules 0.2-0.3 mm, membranous; auricles sometimes present. Inflorescences spikes; disarticulation at the rachis nodes above the spikelets. Spikelets sessile, 2-3 per node, with 1-2(3) florets, often with additional reduced florets distally. Glumes (including awns) equal to unequal, (3.5)4.2-48.5(65) mm, subulate, scabrous to pubescent, obscurely 1-veined, not united; lemmas 5.5-14.3 mm, narrowly elliptic, rounded, glabrous or pubescent, 5-7-veined, veins often prominent apically, apices sharply acute to awned, sometimes with a minute tooth on either side of the awn base, awns (0.9)1.4-34 mm, ascending to slightly divergent, sometimes with a violet tinge; paleas equaling or slightly longer than the lemmas, membranous, scabrous to pilose on and sometimes between the keels, bifid; anthers 3, 3-6.8(7) mm, yellow or violet; lodicules 2, acute, entire, ciliate. Caryopses pubescent apically, tightly enclosed by the lemmas and paleas at maturity. x = 7. Name from the Greek psathyros, fragile, and stachys, spike.

Psathrostachys has eight species, all of which are native to arid regions of central Asia, from eastern Turkey to Xinjiang Province, China and eastern Siberia. One species has been introduced into North America as a potential forage species.

Psathyrostachys is very similar to Leymus, particularly the cespitose species of Leymus. Both genera are monogenomic, having only the N genome. Bödvarsdóttir and Anamthawat-Jónsson (2003) could not find any molecular probes that would distinguish between the two genera.

1.   Psathyrostachys juncea (Fisch.) Nevski
Russian Wildrye

Plants densely cespitose. Culms (20)30-80(120) cm, erect or decumbent at the base, mostly glabrous, pubescent below the spikes. Basal sheaths glabrous, grayish-brown, old sheaths more or less persistent; blades (1)2.5-18(30) cm long, (1)5-20 mm wide, flat or involute, abaxial surfaces smooth or scaberulous, often glaucous; auricles 0.2-1.5 mm; ligules 0.2-0.3 mm. Spikes (3)6-11(16) cm long, 5-17 mm wide, erect; rachises hirsute on the margins, puberulent elsewhere; internodes 3.5-6 mm. Spikelets 7-10(12) mm (excluding the awns), strongly overlapping, the lateral spikelets slightly larger than the central spikelets. Glumes (3.5)4.2-9.4 mm, subulate, scabrous or with 0.3-0.8 mm hairs; lemmas 5.5-7.5 mm, lanceolate, glabrous or with 0.3-0.8 mm hairs, sharply acute or awned, awns 0.8-3.5 mm; paleas 5.8-7.6 mm, scabrous, acute; anthers 2.5-5.1 mm; lodicules 1.3-1.5 mm. Caryopses 4.3-5 mm. 2n = 14, rarely 28.

Psathyrostachys juncea is native to central Asia, primarily to the Russian and Mongolian steppes. It was introduced into North America as a forage grass. It has become established at various locations from the Yukon Territory through the prairie provinces to Arizona. It is drought resistant and tolerant of saline soils. In its native range, it grows on stony slopes and adjacent to roads,at elevations up to 5500 m.

Psathyrostachys juncea closely resembles Leymus cinereus, differing primarily in having a rachis that breaks up at maturity. Immature plants can be identified by their shorter ligules and the more uniform appearance of the spikelets compared to Leymus cinereus. Plants with pilose florets have been treated as a distinct taxon; such recognition is not merited.