Thoracostachyum
Content
Description
Perennial herbs, (in the Mal. spp.) with long-creeping stolons hardening into woody, creeping rhizomes covered with lanceolate acute scales.
Leaves 3-ranked, equitant, subcoriaceous, linear, flat or somewhat folded lengthwise, very gradually narrowed into a very acute to filiform scabrous point, conduplicate at the base (in 2 Indochinese spp. narrowed into a petiole);
Inflorescence terminal, paniculate, with divaricate rigid branches and several to many spikelets;
Flowers hermaphrodite, strongly dorsiventrally compressed, their structure as in Mapania:
Distribution
Africa: Seychelles (Seychelles present), Asia-Tropical, Carolines present, Fiji Islands present
Small genus of about 7 closely related spp.; 1 in the Seychelles, 2 in Indo-China, 1 in the Carolines, 1 in the Fiji Islands, in Malesia 2 spp. I am not certain that they all deserve specific rank.
Notes
The structure of the flowers is not as constant as it is usually assumed. Sometimes the lowest 4 (instead of 3) of the hypogynous scales bear stamens in their axils. UITTIEN () even observed 6 stamens in some of the flowers of T. vitiense UITTIEN all scales then being fertile. T. pacificum HOSOKAWA is described as having 4 or 5 stamens.
Thoracostachyum combines the habit of Hypolytrum with the flower-structure of Mapania. From Hypolytrum the genus is sufficiently distinguished by the different number of hypogynous scales and the 3 stigmas. It is very closely related to Mapania, the only differences with Mapania sect. Cephaloscirpus lying in the paniculate (not capitate) inflorescence, and the hard, non-drupaceous fruit.
Thoracostachyum combines the habit of Hypolytrum with the flower-structure of Mapania. From Hypolytrum the genus is sufficiently distinguished by the different number of hypogynous scales and the 3 stigmas. It is very closely related to Mapania, the only differences with Mapania sect. Cephaloscirpus lying in the paniculate (not capitate) inflorescence, and the hard, non-drupaceous fruit.