Biorepository Data Portal

Plants annual. Culms 25-50 cm; nodes pubescent. Sheaths glabrous, margins ciliate distally; ligules 1-2 mm, ciliate; blades 7-15 cm long, 5-8 mm wide, flat, scabrous, abaxial surface conspicuously hispid over the veins with papillose-based hairs, adaxial surface sparsely hispid over the veins; bristles solitary, 5-15 mm, flexible. Panicles 5-12 cm, loosely spicate; rachises scabrous. Spikelets 1.8-2 mm. Lower glumes about 1/3 as long as the spikelets, 3-veined, lateral veins coalescing with the central vein below the apices; upper glumes about 2/3 as long as the upper lemmas, 5-veined, obtuse; lower paleas equaling the lower lemmas, broad; upper lemmas very strongly and coarsely transversely rugose; upper paleas similar to the upper lemmas. 2n = unknown.

Setaria arizonica is locally abundant in sandy washes on both sides of the Arizona-Sonora border, southwest of Tucson.

FNA 2003

Common Name: Arizona bristlegrass Duration: Annual Nativity: Native Lifeform: Graminoid General: Tufted annual grass, 25-50 cm tall; stems geniculate; nodes pubescent. Vegetative: Sheaths glabrous, the margins ciliate distally; ligules 1-2 mm, ciliate; blades 7-15 cm long, 5-8 mm wide, flat, scabrous, the lower surface conspicuously hispid over the veins with papillose-based hairs, the upper surface sparsely hispid over the veins. Inflorescence: Loosely spicate panicles, 5-12 cm; spikelets 2 mm long and 2-flowered, the lower floret sterile or staminate and the upper floret bisexual; each spikelet subtended by a solitary bristle, 5-15 mm long; lower glumes about 1/3 as long as the spikelets, 3-veined; upper glumes about 2/3 as long as the upper lemmas, 5-veined, obtuse; upper lemmas very strongly and coarsely transversely rugose. Ecology: Found in sandy washes, from 2,000- 4,000 ft (610-1219 m); flowers August-September. Distribution: Pima and Santa Cruz Counties, AZ and neighboring Sonora, MEX, as far south as Navajoa. Notes: Setaria spp. have inflorescences with short, mostly contracted branches and single-seeded, hard spikelets subtended by persistent bristles that remain on the plant after the spikelets have fallen. S arizonica is an annual, locally abundant in sandy washes on both sides of the Arizona-Sonora border, southwest of Tucson. It is distinguished by its loosely paniculate inflorescence, with distinct branching and visible gaps between the branches; this is in comparison to other Setarias which tend to have tighter, spikelike panicles. Note also that each spikelet is subtended by a single bristle. Ethnobotany: Unknown. Synonyms: Panicum appendiculatum, Setaria appendiculata Editor: LCrumbacher2012, AHazelton 2015 Etymology: Setaria comes from the Latin saeta, "a bristle or hair" in reference to the bristly spikelets, while arizonica means of or from Arizona.