Aristida arizonica

HABIT Perennial; caespitose. Butt sheaths withering, or persistent and investing base of culm; with curly dead sheaths. Culms erect; 30–100 cm long. Leaf-sheaths without keel; outer margin glabrous, or hairy. Leaf-sheath oral hairs lacking, or ciliate. Ligule a fringe of hairs; 0.5 mm long. Leaf-blades flat; 10–25 cm long; 1–3 mm wide.

INFLORESCENCE Inflorescence a panicle.

Panicle contracted; linear; 10–25 cm long; bearing few spikelets. Primary panicle branches appressed; 2–6 cm long.

Spikelets solitary. Fertile spikelets sessile.

FERTILE SPIKELETS Spikelets comprising 1 fertile florets; without rhachilla extension. Spikelets linear; subterete; 13–18 mm long; breaking up at maturity; disarticulating below each fertile floret. Floret callus elongated; 1–1.5 mm long; pubescent; pungent.

GLUMES Glumes similar; reaching apex of florets; thinner than fertile lemma. Lower glume lanceolate; 12–17 mm long; 0.9–1 length of upper glume; membranous; 1 -veined. Lower glume lateral veins absent. Lower glume apex setaceously attenuate. Upper glume lanceolate; 13–18 mm long; 1 length of adjacent fertile lemma; membranous; 1 -veined. Upper glume lateral veins absent. Upper glume apex setaceously attenuate.

FLORETS Fertile lemma linear; subterete; 13–16 mm long; coriaceous; without keel; 3 -veined. Lemma margins convolute; covering most of palea. Lemma apex awned; 3 -awned. Principal lemma awn 3-branched; with 20–35 mm long limb; with twisted column. Column of lemma awn 3–6 mm long. Lateral lemma awns 15–30 mm long; shorter than principal.

FLOWER Anthers 3.

DISTRIBUTION North America: northwest USA, southwest USA, south-central USA, and Mexico.

NOTES Aristideae. Gr Tex 1993.

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