Stipa thurberiana

HABIT Perennial; caespitose; clumped densely. Culms 30–70 cm long. Culm-nodes pubescent. Leaf-sheaths glabrous on surface to hirsute. Ligule an eciliate membrane; 2–5 mm long; scaberulous on abaxial surface; lacerate; truncate, or acute. Leaf-blades filiform; involute; 10–15 cm long; 1–2.2 mm wide. Leaf-blade surface scabrous; rough abaxially; pilose; sparsely hairy; hairy adaxially.

INFLORESCENCE Inflorescence a panicle.

Panicle open; linear; 7–13 cm long. Primary panicle branches appressed.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 1 fertile florets; without rhachilla extension. Spikelets lanceolate; subterete; 9–14 mm long; breaking up at maturity; disarticulating below each fertile floret. Floret callus elongated; 1–1.5 mm long; pubescent; pungent.

GLUMES Glumes persistent; similar; exceeding apex of florets; thinner than fertile lemma. Lower glume lanceolate; 1 length of upper glume; membranous; much thinner above; without keels; 3 -veined. Lower glume apex acuminate. Upper glume lanceolate; 9–14 mm long; hyaline; much thinner above; without keels; 3 -veined. Upper glume apex acuminate.

FLORETS Fertile lemma lanceolate; subterete; 7–9 mm long; coriaceous; without keel; 5 -veined. Lemma surface pubescent; hairy all along. Lemma margins convolute; covering most of palea. Lemma apex acute; awned; 1 -awned. Principal lemma awn bigeniculate; 40–50 mm long overall; with twisted column. Middle segment of lemma awn 10 mm long; hirsute. Column of lemma awn 10 mm long; hirsute; with 1–2 mm long hairs. Palea 0.8 length of lemma; coriaceous (at tip); 2 -veined; without keels.

FLOWER Lodicules 3; 2 mm long. Anthers 3; 3–4 mm long; anther tip smooth. Stigmas 2. Ovary glabrous.

FRUIT Caryopsis with adherent pericarp. Hilum linear.

DISTRIBUTION North America: northwest USA and southwest USA.

NOTES Stipeae. Fl Pac NW 1994.

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