Plants rhizomatous. Culms 1-2 m tall, 2-4 mm thick. Lower sheaths hispid; upper sheaths essentially glabrous; ligules erose, not ciliate; blades to 100 cm long, 8-30 mm wide, glabrous or slightly pubescent. Terminal inflorescences with 4-7(10) rames. Pistillate spikelets 2-3 mm wide, beadlike in appearance. Staminate spikelets in sessile-pedicellate pairs; glumes 5-10 mm long, 1.5-2 mm wide, usually membranous, acute; pedicels 2-5 mm long, less than 0.3 mm wide, almost flat to plano-convex in cross section, flexible. 2n = 72.

Tripsacum lanceolatum grows in moist soil (often in canyon bottoms) of mountains from southeastern Arizona and southwestern New Mexico through Mexico to Guatemala. It has not been found in New Mexico since the 1800s.

FNA 2007, Gould 1980

Common Name: Mexican gamagrass Duration: Perennial Nativity: Native Lifeform: Graminoid General: Rhizomatous perennial from thick, knotty rhizomes in large clumps with stems 1-2 m tall, 2-4 mm thick. Vegetative: Lower sheaths hispid, upper essentially glabrous, blades to 1 m long, 8-30 mm wide, tapering to a slender tip, ligule a membranous collar, 1 mm, erose. Inflorescence: Spicate raceme in clusters of 4-7 rames (an inflorescence with branches bearing stalked and sessile spikelets); pistillate spikelets 2-3 mm wide, beadlike in appearance, staminate spikelets in sessile-pedicellate pairs, one sessile and one pedicellate, pedicels 2-5 mm long, less than 0.3 mm wide, flat to plano convex in cross section, glumes 5-10 mm long, 1.5-2 mm wide, membranous and acute. Ecology: Found in moist soil in canyon bottoms, at the foot of slopes and in rocky draws from 4,000-6,000 ft (1219-1829 m); flowers August-October. Notes: Very large grass, sometimes 1 m in diameter across for some clumps. A notable genus as you move south into Mexico, as it is linked closely with the genus Euchlaena (teosinte) which is known to be the progenitor of Zea mays. The thick stem and the emergence of multiple spikes right out of the sheath. Ethnobotany: Unknown Etymology: Tripsacum comes from an unknown source, while lanceolatum means lance shaped, presumably for its leaves. Synonyms: None Editor: SBuckley, 2010