Plants cespitose, with a knotty base of short rhizomes. Culms 20-100 cm, suberect to spreading, stiff, simple to sparingly branched. Sheaths mostly glabrous, throats sometimes pubescent; collars conspicuously pubescent; ligules about 0.2 mm; blades (1.5)2.5-12 cm long, (2)5-10(18) mm wide, somewhat cordate at the base, mostly glabrous, often pubescent near the basal margins. Panicles (6)11.5-30(35) cm; branches (3)7-24 cm, stiffly spreading to somewhat reflexed, spikelet-bearing from the base, spikelets remote to slightly imbricate. Spikelets with 1(2) florets. Glumes 4-7 mm; calluses bearded; bisexual lemmas 2.5-5(6) mm, awns 4-12.2 mm; second florets often reduced to an obliquely inserted 2.4-6.2 mm awn; anthers 3, 0.8-1.2 mm. Caryopses 2-3 mm long, 0.2-0.5 mm wide. 2n = 40.

Gymnopogon ambiguus grows in sandy pine woodlands of the southeastern United States, Haiti, and the Dominican Republic. It often grows with G. brevifolius, from which it differs in being more robust, having long, wider leaves, longer lemma awns, and, usually, having panicle branches that are spikelet-bearing to the base. Although spikelets of Gymnopogon ambiguus usually have only one floret, several plants from Texas have been found in which two florets per spikelet were the norm.

There is an 1853 collection of G. ambiguus supposedly from Doña Ana County, New Mexico, but there have been no recent collections from anywhere near there; it is possible that the locality data on the label are incorrect.

On September 19, 1934, I found a large colony of this species in very sandy soil on the crest of a sand ridge in an open place in a woods in sec. 35 about 5 miles north- west of Washington, Daviess County. In 1938 Kriebel found it here and in a woods a mile southwest of Plainville and in a woods 4 miles north of Washington.

Culms mostly solitary, 3-6 dm; lvs crowded toward the base; sheaths overlapping; blades divaricate, the larger 5-10 cm נ6-12 mm, rounded or subcordate at base, glabrous; panicle constituting a third to half of the entire shoot; spikes numerous, 10-15 cm, at first erect, later widely and stiffly divaricate; spikelets remote, the summit of the glumes barely or not reaching the base of the next above; glumes 4-6 mm; lemma 3.5-4.3 mm, sparsely pilose-ciliate; awn straight, 4.5-9 mm; rachilla prolonged nearly to the summit of the lemma, there bearing an awn 1-5 mm. Dry sandy woods and barrens; coastal plain from s. N.J. to Fla. and Tex., and in the interior from s. O. and Ky. to s. Mo. and southward.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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