Trisetum virletii

HABIT Perennial. Rhizomes elongated. Culms erect, or rambling; 200–300 cm long; 5–10 mm diam. Lateral branches ample; extravaginal. Ligule a ciliolate membrane; 2–5 mm long; truncate. Leaf-blades 30–45 cm long; 8–13 mm wide. Leaf-blade surface glabrous; hairless except near base.

INFLORESCENCE Inflorescence a panicle.

Panicle open; elliptic; loose, or effuse; nodding; 20–45 cm long. Primary panicle branches ascending, or drooping; 10–15 cm long. Panicle branches scabrous.

Spikelets solitary. Fertile spikelets pedicelled. Pedicels flexuous; 1.5–2 mm long.

FERTILE SPIKELETS Spikelets comprising 3–5 fertile florets; with diminished florets at the apex. Spikelets oblong; laterally compressed; 6–7.5 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes 1 mm long; pilose; with 3 mm long hairs. Floret callus pubescent.

GLUMES Glumes persistent; similar; shorter than spikelet; thinner than fertile lemma; shiny; gaping. Lower glume elliptic; 4–5 mm long; 0.8 length of upper glume; membranous; 1-keeled; 1 -veined. Lower glume lateral veins absent. Lower glume apex acute, or setaceously attenuate. Upper glume elliptic; 5–6.5 mm long; 1.1 length of adjacent fertile lemma; membranous; 1-keeled; 3 -veined. Upper glume apex acute, or setaceously attenuate.

FLORETS Fertile lemma lanceolate; 4.5–6 mm long; membranous; keeled; 5 -veined. Lemma surface asperulous. Lemma apex dentate; 2 -fid; obtuse, or acute; awned; 1 -awned. Principal lemma awn dorsal; arising 0.66 way up back of lemma; geniculate; 2–4 mm long overall; with twisted column. Palea gaping; 4–5 mm long; hyaline. Apical sterile florets resembling fertile though underdeveloped.

FLOWER Anthers 3; 2.5–3 mm long. Ovary glabrous.

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

DISTRIBUTION North America: Mexico.

NOTES Aveneae. Fl Nov Gal 1994.

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