Stipa stillmanii

HABIT Perennial; caespitose. Culms erect; 70–100 cm long; 4–5 -noded. Leaf-sheaths glabrous on surface. Leaf-sheath oral hairs pubescent. Ligule a fringe of hairs. Leaf-blades 15–30 cm long; 3–6 mm wide. Leaf-blade surface ribbed; scabrous; rough adaxially.

INFLORESCENCE Inflorescence a panicle.

Panicle contracted; linear; interrupted; 10–20 cm long. Panicle branches scabrous.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 1 fertile florets; without rhachilla extension. Spikelets lanceolate; subterete; 15–18 mm long; breaking up at maturity; disarticulating below each fertile floret. Floret callus evident; 1 mm long; pilose; obtuse.

GLUMES Glumes persistent; similar; exceeding apex of florets; thinner than fertile lemma. Lower glume lanceolate; 1 length of upper glume; membranous; without keels; 1 -veined. Lower glume lateral veins absent. Lower glume surface asperulous. Lower glume apex acuminate; awned; 1 -awned. Lower glume awn 2–3 mm long. Upper glume lanceolate; 15–28 mm long; membranous; without keels; 3–5 -veined. Upper glume surface asperulous. Upper glume apex acuminate; awned; 1 -awned. Upper glume awn 2–3 mm long.

FLORETS Fertile lemma lanceolate; subterete; 8 mm long; membranous; pallid; without keel; 5 -veined. Lemma surface pubescent. Lemma margins flat; covering most of palea. Lemma apex lobed; 2 -fid; with lobes 2–3 mm long; awned; 1 -awned. Principal lemma awn from a sinus; geniculate; 25–30 mm long overall; with twisted column. Palea 1 length of lemma; 2 -veined; without keels.

FLOWER Lodicules 3. Anthers 3; anther tip smooth. Stigmas 2. Ovary glabrous.

FRUIT Caryopsis with adherent pericarp; fusiform. Hilum linear.

DISTRIBUTION North America: southwest USA.

NOTES Stipeae. Hitchcock 1995.

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