Maguire, Bassett. 1967. The botany of the Guayana Highland--Part VII. Mem. New York Bot. Gard. 17: 1-439.
Cyperaceae
Genus Description - Plants perennial, sometimes with elongate rhizomes. Leaves radical and cauline, sometimes in part obscurely 2-ranked; laminae linear or linear-lanceolate, 1- or 3-costate; sheaths frequently purplish-tinged, orifice truncate, pubescent, sometimes with deltoid contra-ligule. Culms central or lateral, in the latter case surrounded at base with bladeless sheaths. Inflorescences at few to several nodes of culms paniculate-cymose with many small globose heads and verticillate rays, rarely congested in a terminal head; bracts leaf-like. Spikes compound, sessile or short-peduncled; glumes 6 (including a prophyll); prophyll and the lower 2 empty; the upper 3 bearing an axillary staminate spikelet; fructification solitary, terminal; cupule utricle-shaped, upper part hyaline, puberulent, open only at the tip with a small orifice, the base thickened and spongy; achene globose or lenticular, white, bony; stigmas 3 or 2.
Distribution and Ecology - Distribution. Widely distributed in tropical America, from southern Mexico throughout Central America southwards to Bolivia and southeastwards to eastern Brazil covering the entire Guayana and the Guianas, absent from the West Indies except in the islands Trinidad and Tobago. Five species as undergrowth of tropical rainforest.
Heteranthe Schrader ex Xees, Fl. Brasil. 2(1): 193-195. 1842. Nomen invalidum. Becquerelia Brongn. subg Calyptrocarya (Nees) H. Pfeiffer, Repert. Sp. Nov. 18: 380. 1922
Taxonomic difficulty in this small genus consists in the great variability in plant parts. As most species are phenotypically similar, the specific separation depends principally on the dimensions of fructifications, or leaf blades, or both. This fact has prevented previous workers from satisfactory segregation of specie's since they did not have access to sufficient material. The species of the Calyptrocarya poeppigiana complex and the C. glomerulata complex have been defined through careful measurements made on ample collections deposited at The New York Botanical Garden, the U. S. National Herbarium, and the Harvard University Herbarium. Because of the difference in the spikelet structure (see discussion in the general part) C. bullata has been removed from the genus, and a new species is proposed from the Guayana region. The century-old nomencla-tural confusion is clarified, and five species are recognized as valid.