Cryptangium Schrad. ex Nees, Flora Brasiliensis (Martius) 2(1): 163 (1842).

Lagenocarpus section Corymbosae H. Pfeiffer, Repert. Sp. nov. 18: 87 (1922).; emend. T.Koyama & Maguire, Mem. N.Y. Bot. Gard. 12 (3): 48 (1965).

Monoecious herbs, with short and/or creeping rhizome; caudex absent.Leaf blades reduced to sheaths or well-developed; long lanceolate to linear when developed, margins glabrous to hairy at base and increasingly scabrid towards apex. Inflorescence terminal, solitary, panicle-like. Involucral bracts leaf-like, with linear-lanceolate to lanceolate blades. Paracladia monomorphic: male and female spikelets mixed in the paracladia (female generally distal). Male spikelets 6–7 flowered; stamens 2 per flower, rarely 3. Female spikelets 1(2)-flowered, 3 glumes; stigmas 3. Glumes spirally or sub-distichally arranged. Fruit (nutlet) stipitate, obovoid, trigonous with noticeable ridges, with conspicuous cavities at the base, glabrous or with some trichomes in the ridges at the sides of cavities; hypogynous scales reduced and glabrous; beak short conical and glabrous, persistent.

The genus occurs in non-Andean South America regions, from of Guyana and Brazilian Shields southwards to southern areas of Brazil (probably São Paulo state), from western Brazilian coast to eastern Colombian Vaupés, on sandy soils. Total number of species: 1 (one).

The only species accepted to Cryptangium was under the name Lagenocarpus verticillatus (Sprengel) T.Koyama & Maguire, according to Koyama (2004). There is a. manuscript dealing with the history and combination of this species submitted and to be published soon (Fábio Vitta, personal communication).