Plants perennial; loosely cespitose. Culms 6–75 cm, not woody; nodes numerous, swollen. Sheaths open; adaxial ligules membranous; pseudopetioles 1–2 mm; bladeslanceolate to ovate, folding downwards at night or when stressed, bases and apices asymmetric. Inflorescences racemes, partly enclosed by the leaf sheaths; axillary racemes unisexual or bisexual, if bisexual, the staminate spikelets below 1 to several pistillate spikelets, pedicels clavate; terminal racemes staminate, pedicels filiform. Spikelets with 1 floret. Pistillate spikelets much larger than the staminate spikelets, floret borne on a persistent peglike rachilla internode; glumes exceeding the floret, subequal, several-veined; lemmas helmet-shaped, indurate, laterally compressed, the margins from overlapping the palea margins to nearly concealing the paleas; style branches 2, plumose. Staminate spikelets lanceolate, early deciduous; glumes absent; lemmas translucent, 3-veined; anthers 3. x = 11. Name from the Greek litho, ‘stony’, and achne, ‘scale’ or ‘chaff’, a reference to the indurate lemma and palea of the pistillate floret.
Lithachne has four species. Its primary range extends south from Mexico and the Caribbean islands to Ecuador, but there are disjunct populations in Peru, southern Brazil, northern Argentina, and Paraguay. One species is sold as an ornamental in the United States.
SELECTED REFERENCES Judziewicz, E.J. 1990. Flora of the Guianas: 187. Poaceae (series ed. A.R.A. Görts-van Rijn). Koeltz Scientific Books, Koenigstein, Germany. 727 pp.; Judziewicz, E.J., L.G. Clark, X. Londoño, and M.J. Stern. 1999. American Bamboos. Smithsonian Institution Press, Washington, D.C., U.S.A. 392 pp.; Paisooksantivatana, Y. and R.W. Pohl. 1992. Morphology, anatomy and cytology of the genus Lithachne (Poaceae: Bambusoideae). Revista Biol. Trop. 40:47–72; Pohl, R.W. 1994. Lithachne P. Beauv. Pp. 215–216 in G. Davidse, M. Sousa S., and A.O. Chater (eds.). Flora Mesoamericana, vol. 6: Alismataceae a Cyperaceae. Universidad Nacional Autónoma de México, Instituto de Biología, México, D.F., México. 543 pp.; Soderstrom, T.R. 1980. A new species of Lithachne (Poaceae: Bambusoideae) and remarks on its sleep movements. Brittonia 32:495–501.