Setaria arizonica

HABIT Annual. Culms erect, or geniculately ascending; 25–50 cm long. Culm-nodes pubescent. Leaf-sheaths glabrous on surface; outer margin hairy. Ligule a fringe of hairs; 1–2 mm long. Leaf-blades 7–15 cm long; 5–8 mm wide. Leaf-blade surface scabrous; rough adaxially; pilose; hairy adaxially; with tubercle-based hairs.

INFLORESCENCE Inflorescence a panicle. Peduncle scaberulous above.

Panicle spiciform; linear; loose; tapering above; 5–12 cm long. Primary panicle branches 0.5–1.5 cm long; sterile at the tips. Panicle axis angular; scabrous. Panicle branches scabrous.

Spikelets subtended by an involucre. Fertile spikelets pedicelled; 1 in the cluster. Involucre composed of bristles; 5–15 mm long. Involucral bristles persistent; 1 per spikelet; flexible; antrorsely scaberulous; glabrous. Pedicels oblong.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets ovate; dorsally compressed; 1.8–2 mm long; falling entire.

GLUMES Glumes shorter than spikelet; thinner than fertile lemma. Lower glume ovate; 0.5 length of spikelet; membranous; without keels; 3 -veined. Lower glume apex acute. Upper glume ovate; 0.66 length of spikelet; membranous; without keels; 5 -veined. Upper glume apex obtuse.

FLORETS Basal sterile florets barren; with palea. Lemma of lower sterile floret ovate; 1 length of spikelet; membranous; 5 -veined; acute. Palea of lower sterile floret 1 length of lemma. Fertile lemma ovate; dorsally compressed; gibbous; 1.8–2 mm long; indurate; without keel. Lemma surface corrugate. Lemma margins involute. Palea involute; indurate. Palea surface rugose.

DISTRIBUTION North America: southwest USA.

NOTES Paniceae. Rominger 1994.

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