Trisetum filifolium

HABIT Perennial; caespitose; clumped loosely. Butt sheaths persistent and investing base of culm. Culms geniculately ascending; 50–100 cm long. Leaves mostly basal. Leaf-sheaths antrorsely scabrous. Ligule an eciliate membrane; 0.5–1 mm long; entire. Leaf-blades flexuous; filiform; involute; 15–30 cm long; 0.5–1 mm wide. Leaf-blade surface scabrous.

INFLORESCENCE Inflorescence a panicle. Peduncle scaberulous above.

Panicle open; elliptic; nodding; 10–15 cm long. Primary panicle branches appressed, or ascending. Panicle axis angular; scabrous. Panicle branches capillary; pubescent.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 3 fertile florets; with a barren rhachilla extension. Spikelets oblong; laterally compressed; 5–6 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes pilose. Floret callus pubescent. Floret callus hairs 0.5 mm long.

GLUMES Glumes persistent; similar; shorter than spikelet; thinner than fertile lemma; shiny. Lower glume oblong; 4 mm long; 1 length of upper glume; membranous; 1-keeled; 1 -veined. Lower glume lateral veins absent. Lower glume apex acute. Upper glume oblong; 4 mm long; 1 length of adjacent fertile lemma; membranous; 1-keeled; 3 -veined. Upper glume apex acute.

FLORETS Fertile lemma oblong; 4 mm long; membranous; keeled; 5 -veined. Lemma surface scaberulous. Lemma apex dentate; 2 -fid; awned; 1 -awned. Principal lemma awn dorsal; arising 0.5–0.66 way up back of lemma; geniculate; 4–5 mm long overall; with twisted column. Palea gaping; hyaline. Rhachilla extension pilose.

FLOWER Anthers 3.

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

DISTRIBUTION North America: Mexico.

NOTES Aveneae. N Amer Fl 1994.

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