Genomic constitution

N, by assignment. Only diploids are known.

Distinguishing features

Perennial plants that are not rhizomatous. Spikelets usually three per node, sometimes two, with narrow, subulate glumes. The inflorescence breaks up at maturity, sometimes tardily. Lemmas usually awned (only awn-tipped in Psathyrostachys juncea, the species that has been introduced into different parts of the world for soil stabilization).

Description

Plants perennial, cespitose, forming dense or loose tufts, sometimes rhizomatous or stoloniferous. Culms erect, 15-90(110) cm tall.

Sheaths becoming subfibrillose to fibrillose with age; blades of lower leaves 0.8-18 mm wide.

Inflorescences spikelike, 1-11(12.5) cm long, erect; middle internodes 2.4-3.9(4.6) mm long; disarticulation in the rachis, breaking up at maturity, the spikelets falling with the internode below.

Spikelets ellipsoid, usually 3, occasionally 2 per node, all sessile, usually with 2 florets, the lower fertile the upper sterile or rudimentary, occasionally with 2 fertile florets and a rudimenary or sterile third floret.

Glumes subulate, equal to subequal, scabrous to hairy, not united at the base. Lemmas mucronate to awned, awns, sometimes a minute tooth on either side of the awn; paleas equaling or slightly longer than the lemmas; lodicules acute, entire, ciliate; anthers 3, 3-7.5 mm long.

Size

There are about 8 species of Psathyrostachys. There is a listing at http://herbarium.usu.edu/Triticeae/Psathyrostachys.htm

Distribution

Western,central, and eastern Asia.

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Miscellaneous comments

Psathyrostachys juncea is used for soild stabilization in the U.S. and has become established there.

Alternative interpretations

Most taxonomists now accept Psathyrostachys.

Type species

Psathyrostachys lanuginosa (Trin.) Nevski

Known problems

No known problems. A phylogeny of the N genome species would be highly desirable.

References

Baden, C. 1991. A taxonomic revision of Psathyrostachys (Poaceae). Nordic J. Bot. 11:3-26.

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