Stipa swallenii

HABIT Perennial; caespitose; clumped densely. Culms erect; 15–40 cm long. Leaf-sheaths smooth. Ligule an eciliate membrane; 3 mm long; erose, or trilobed; truncate. Leaf-blades erect; filiform; involute; 3–6 cm long; 0.3–0.5 mm wide; stiff. Leaf-blade surface scabrous.

INFLORESCENCE Inflorescence a panicle. Peduncle antrorsely scabrous above.

Panicle contracted; linear; 5–6 cm long. Primary panicle branches appressed.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 1 fertile florets; without rhachilla extension. Spikelets elliptic; dorsally compressed; 5–6 mm long; breaking up at maturity; disarticulating below each fertile floret. Floret callus pubescent; obtuse.

GLUMES Glumes persistent; similar; exceeding apex of florets; thinner than fertile lemma. Lower glume elliptic; 5–6 mm long; 1 length of upper glume; hyaline; purple; without keels; 3 -veined. Lower glume surface glabrous, or puberulous. Lower glume apex acute. Upper glume elliptic; 5–6 mm long; 1.6 length of adjacent fertile lemma; hyaline; purple; without keels; 3 -veined. Upper glume surface glabrous, or puberulous. Upper glume apex acute.

FLORETS Fertile lemma elliptic; subterete; 3–3.5 mm long; membranous; without keel. Lemma surface pubescent. Lemma margins flat; covering most of palea. Lemma apex dentate; 2 -fid; obtuse; awned; 1 -awned. Principal lemma awn from a sinus; geniculate; 5–6 mm long overall; with twisted column; deciduous. Palea 1 length of lemma; coriaceous; 2 -veined; without keels.

FLOWER Lodicules 3; oblong; 1.5 mm long; ciliate. Anthers 3; 2 mm long; anther tip penicillate. Stigmas 2.

DISTRIBUTION North America: northwest USA.

NOTES Stipeae. Fl Pac NW 2000.

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