Trisetum orthochaetum

HABIT Perennial; caespitose. Culms 110 cm long. Ligule an eciliate membrane; 3–5 mm long; pubescent on abaxial surface; entire; obtuse. Leaf-blades 8–20 cm long; 4–7 mm wide.

INFLORESCENCE Inflorescence a panicle.

Panicle open; lanceolate; 15–18 cm long. Primary panicle branches ascending; 4–8 cm long. Panicle branches capillary.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 3 fertile florets; with a barren rhachilla extension. Spikelets oblong; laterally compressed; 8–9 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes pilose; with 1 mm long hairs. Floret callus pubescent.

GLUMES Glumes persistent; similar; shorter than spikelet; thinner than fertile lemma; shiny. Lower glume lanceolate; 5.5 mm long; 0.9 length of upper glume; membranous; 1-keeled; 1 -veined. Lower glume lateral veins absent. Lower glume apex acuminate. Upper glume lanceolate; 6.3 mm long; 1 length of adjacent fertile lemma; membranous; 1-keeled; 3 -veined. Upper glume apex acute.

FLORETS Fertile lemma oblong; 6 mm long; membranous; keeled; 5 -veined. Lemma apex dentate; 2 -fid; awned; 1 -awned. Principal lemma awn dorsal; arising 0.75–0.8 way up back of lemma; straight, or curved; 5–6 mm long overall. Palea gaping; hyaline. Rhachilla extension pilose.

FLOWER Anthers 3; 1 mm long.

FRUIT Caryopsis with adherent pericarp. Hilum punctiform. Endosperm soft.

DISTRIBUTION North America: northwest USA.

NOTES Aveneae. Fl Pac NW 1994.

Please cite this publication as detailed in How to Cite Version: 3rd February 2016.