Deyeuxia tweedyi

HABIT Perennial. Rhizomes short. Butt sheaths persistent and investing base of culm; with fibrous dead sheaths. Culms 60–150 cm long. Lateral branches lacking. Leaves basal and cauline. Ligule an eciliate membrane; 6–15 mm long; erose, or lacerate. Leaf-blades 5–20 cm long; 7–13 mm wide. Leaf-blade surface scabrous; rough adaxially.

INFLORESCENCE Inflorescence a panicle.

Panicle contracted; linear, or lanceolate; continuous, or interrupted; 8–16 cm long; 2 cm wide.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 1 fertile florets; with a barren rhachilla extension. Spikelets lanceolate; laterally compressed; 5.5–7 mm long; breaking up at maturity; disarticulating below each fertile floret. Floret callus pubescent. Floret callus hairs 0.5–1 mm long; 0.1 length of lemma.

GLUMES Glumes persistent; similar; exceeding apex of florets; firmer than fertile lemma. Lower glume lanceolate; 1 length of upper glume; membranous; 1-keeled; 1 -veined. Lower glume lateral veins absent. Lower glume apex acute. Upper glume lanceolate; 5.5–7 mm long; 1.1 length of adjacent fertile lemma; membranous; 1-keeled; 1–3 -veined. Upper glume apex acute.

FLORETS Fertile lemma lanceolate; 5–6.5 mm long; membranous; without keel; 5 -veined. Lemma surface scaberulous. Lemma apex dentate; 4 -fid; awned; 1 -awned. Principal lemma awn dorsal; arising 0.5 way up back of lemma; geniculate; 10–12 mm long overall; clearly exserted from spikelet; with twisted column. Palea 1 length of lemma. Rhachilla extension 2–4 mm long; villous.

FLOWER Lodicules 2; 1–1.5 mm long. Anthers 3; 4 mm long; purple. Stigmas 2.

FRUIT Caryopsis with adherent pericarp. Hilum punctiform. Disseminule comprising a floret.

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.