17.02   UNIOLA L.
H. Oliver Yates

Plants perennial; rhizomatous or stoloniferous. Culms to 2.5 m, erect, glabrous, unbranched. Ligules of hairs; blades flat, becoming involute when dry, margins scabrous, tapering to an attenuate apex. Inflorescences terminal, simple panicles, exceeding the leaves; disarticulation below the glumes. Spikelets 8-50 mm long, 6-16 mm wide, ovate-elliptical to ovate-triangular, strongly laterally compressed, with 3-34 florets, lowest 2-8 florets sterile, remaining floret(s) bisexual. Glumes subequal, shorter than the adjacent lemmas, midveins keeled, serrate to serrulate, apices unawned; lemmas 3-9-veined, midveins keeled, serrate to serrulate, apices somewhat blunt to acute or mucronate, unawned; paleas, if present, from slightly shorter than to exceeding the lemmas, 2-keeled, keels winged, serrulate or ciliate; anthers 3; ovary glabrous; styles 1, with 2 style branches. Caryopses linear; embryos less than 1/2 as long as the caryopses. x = 10. Name from the Latin unione glumarum, united bracts, apparently a reference to the spikelets.

Uniola has two species, both of which grow on coastal sand dunes. There is one species native to the Flora region; the second, U. pittieri Hack., extends from northern Mexico to Ecuador, primarily along the Pacific coast. Uniola used to be interpreted as including Chasmanthium, a genus that is now included in the Centothecoideae.


SELECTED REFERENCES Grass Phylogeny Working Group. 2001. Phylogeny and subfamilial classification of the grasses (Poaceae). Ann. Missouri Bot. Gard. 88:373-457; Yates, H.O. 1966a. Morphology and cytology of Uniola (Gramineae). SouthW. Naturalist 11:145-189; Yates, H.O.1966b. Revision of grasses traditionally referred to Uniola, I. Uniola and Leptochloöpsis. SouthW. Naturalist 11:372-394; Yates, H.O. 1966c. Revision of grasses traditionally referred to Uniola, II. Chasmanthium. SouthW. Naturalist 11:415-455.

1.   Uniola paniculata L.
Sea Oats

Plants perennial; rhizomatous. Culms to 2.5 m. Sheaths glabrate, mostly glabrous at maturity, with tufts of hairs near the collar; collars ciliate to pubescent; blades to 67 cm long, about 1 cm wide. Panicles 27-67 cm, open; branches drooping or nodding at maturity. Spikelets 15-30(50) mm long, 6-16 mm wide, ovate-elliptical, with (3)5-34 florets, the lower (3)4-5(8) sterile. Glumes 5-12 mm, acute; lemmas essentially glabrous, (7)9(13)-veined; paleas present only in the functional florets; anthers 4-6 mm. Caryopses 3-5 mm long, 1-1.5 mm wide. 2n = 40.

Uniola paniculata grows on the beaches and sand dunes of the Atlantic and Gulf coastal plains from Maryland to Veracruz, Mexico, and on the Florida Keys, the Bahama Islands, and Cuba. Seed production is generally poor; the reason is not known.