Monochoria vaginalis var. Angustifolia, a new variety of the Pontederiaceae from Thailand
泰国雨久花属(雨久花科)一新变种--窄叶鸭舌草

A new variety of Monochoria C. Presl from Thailand, M. vaginalis (N. L. Burman) Kunth var. angustifolia G. X. Wang, is described. This variety can be distinguished from the typical one, M. vaginalis var. vaginalis, by having mature leaves narrowly lanceolate, 3-7×0.3-2.0 cm with the basal lobes up to 0.2 cm long, apex acute or acuminate, and 3-7-flowered raceme. In M. vaginalis var. vaginalis the mature leaves are elliptic to cordate, 4-9×2-8 cm, the basal lobes up to 2 cm long, and raceme 6-10-flowered.