Stipa richardsonii

HABIT Perennial; caespitose. Culms 40–100 cm long. Leaves mostly basal. Leaf-sheaths glabrous on surface, or puberulous. Ligule an eciliate membrane; 0.5 mm long. Leaf-blades conduplicate, or involute; 15–25 cm long; 1.5–3 mm wide. Leaf-blade surface scaberulous.

INFLORESCENCE Inflorescence a panicle.

Panicle open; pyramidal; 7–20 cm long. Primary panicle branches spreading, or drooping.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 1 fertile florets; without rhachilla extension. Spikelets lanceolate; subterete; 8–10 mm long; breaking up at maturity; disarticulating below each fertile floret. Floret callus evident; 1 mm long; pubescent; acute.

GLUMES Glumes persistent; similar; exceeding apex of florets; thinner than fertile lemma. Lower glume lanceolate; 8–10 mm long; 1.3 length of upper glume; membranous; without keels; 5 -veined. Lower glume apex acuminate. Upper glume lanceolate; 6–7.5 mm long; hyaline; without keels; 3 -veined. Upper glume apex acuminate.

FLORETS Fertile lemma lanceolate; subterete; 5–6 mm long; membranous; light brown; without keel; 5 -veined. Lemma surface pubescent. Lemma margins flat; covering most of palea. Lemma apex acute; awned; 1 -awned. Principal lemma awn bigeniculate; 18–25 mm long overall; with twisted column. Middle segment of lemma awn pubescent. Column of lemma awn hirtellous. Palea 0.75 length of lemma; 2 -veined; without keels.

FLOWER Lodicules 3; 1.5 mm long. Anthers 3; 2 mm long; anther tip penicillate. Stigmas 2. Ovary glabrous.

FRUIT Caryopsis with adherent pericarp. Hilum linear.

DISTRIBUTION North America: Subarctic, western Canada, northwest USA, and north-central USA.

NOTES Stipeae. Fl Pac NW 1994.

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