Trisetum orthochaetum

Illustrator: Cindy Roché

Copyright: Utah State University

Plants perennial, with both fertile and sterile shoots; shortly rhizomatous. Culms 80-110 cm, solitary, decumbent, often anthocyanic at the base, glabrous. Leaves evenly distributed; sheaths usually glabrous; ligules 3-5 mm, truncate or rounded, erose; blades 8-20 cm long, 3-7 mm wide, flat, lax, scabrous. Panicles 13-20 cm, narrow, moderately dense, nodding, pale green, slightly tinged with purple; branches loosely ascending, naked below for 1-2 cm, the spikelets closely and evenly distributed distally. Spikelets 7-9 mm, subsessile or on pedicels to 1 cm, oblong-ovate, with 2-3(4) florets; rachilla internodes to 2 mm; rachilla hairs about 1 mm. Glumes lanceolate or oblanceolate; lower glumes about 5.5 mm long, about 1 mm wide, widest near the base, slenderly acuminate; upper glumes to 6.3 mm long, about 2 mm wide at or just above the middle, acuminate; callus hairs about 0.5 mm; lemmas 5-6.5 mm long, about 1/3 as wide as long, apices bifid, teeth shorter than 1 mm, awned, awns 4-6 mm, arising about 1 mm below the teeth, not twisted basally, straight or flexuous, exceeding the lemma apices; paleas almost equaling the lemmas; anthers minute or to 1 mm, appearing non-functional; ovaries pubescent. Caryopses to 2.5 mm, malformed. 2n = unknown.

Distribution

• Generated Map
• Legacy Map

Mont.

Discussion

Trisetum orthochaetum is known only from Montana, in or near the edges of marshes, seeps, and creeksides, where it grows at about 1465 m. It may be a sterile hybrid between T. canescens and T. wolfii (Shelly 1987).

Selected References

None.

Lower Taxa

None.