Exochogyne C.B.Clarke, Verh. Bot. Vereins Berlin Brandenburg

Costa, Suzana M., Vitta, Fabio A., Thomas, William W., Muasya, A. Muthama, Morokawa, Rosemeri, Bittrich, Volker, Shepherd, George J. & Do Amaral, Maria Do Carmo E., 2021, An updated generic circumscription for Cryptangieae (Cyperaceae, Poales) based on a molecular phylogeny and a morphological character reconstruction, Phytotaxa 483 (3), pp. 211-228 : 225

Exochogyne C.B.Clarke, Verh. Bot. Vereins Berlin Brandenburg 47: 101 (1905).

Type species: Exochogyne amazonica C.B.Clarke

Lagenocarpus section Exochogyne (C.B.Clarke) T.Koyama, Makinoa , new series 4: 47 (2004).

Monoecious herbs, with short creeping rhizome; caudex absent. Leaf blades well-developed, linear-lanceolate. Inflorescence terminal, solitary, congested or laxly spike-like. Involucral bracts leaf-like, with linear-lanceolate to lanceolate blades, expanded at base and enclosing the paracladia. Paracladia monomorphic: male and female spikelets mixed in the paracladia. Male spikelets multiflowered; stamens 2 per flower (rarely 4 or 6). Female spikelets 1 flowered, 4 glumes; stigmas 2. Glumes distichally arranged. Fruit (nutlet) abruptly or gradually attenuate at base, ovoid, ellipsoid or obovoid, biconvex with distinguishable ridges, glabrous; hypogynous scales absent; beak conical, persistent.

This genus occurs in northern South America, on the eastern Guyana Shield and in the Amazon basin, mainly in open vegetation, but is also found in forested white-sand savannas, on nutrient poor sandy soils and among rocks. Total number of species: 2.

Exochogyne lacks both the trigonous nutlet and the hypogynous scales typical of Cryptangieae and presents a spike-like inflorescence uncharacteristic for the tribe. Typical morphological characters of the tribe that also occur in the genus include the unisexual spikelets and the reddish-pink stigmas, and also the distribution more centered in the Amazon biome on poor nutrient soils. The genus was considered as incertae sedis by Goetghebeur (1998) but its species are included in Lagenocarpus in Koyama’s morphology based works (2004) and included in Cryptangieae based on molecular data in Muasya et al. (2009).

1. Exochogyne amazonica C.B.Clarke, Verh. Bot. Vereins Berlin Brandenburg 47: 101 (1906).

2. Exochogyne steyermarkii Gilly, Fieldiana, Bot. 28(1): 53 (1951).