Thoracostachyum

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Thoracostachyum

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.

Uses

T. sumatranum is sometimes used for making mats.

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.

Citation

UITTIEN - in Rec. Trav. Bot. Néerl. 1936: 133