Impatiens rapiformis, a new species of Impatiens with root tuber from Yunnan, China

Impatiens rapiformis (Balsaminaceae), a new species from Malipo County, Yunnan, China, is described and illustrated. The new species is superficially similar to I. apalophylla, I. malipoensis and I. guizhouensis, but differs by having cylindric or subfusiform root tuber, elliptic or obovate-oblong leaf blades and falcate outer lateral sepals. The characters of its seed micromorphology and pollen morphology under SEM are given. A preliminary molecular phylogenetic study suggests that I. rapiformis should be placed in I. subg. Clavicarpa.