Henckelia siangensis, a new species from Arunachal Pradesh of Northeast India, is described and illustrated here. The new species is remarkably different from all other allied species by its 5-winged calyx and elliptic-ovate calyx segments. It superficially resembles H. calva in glabrous stem and petioles, but differs from it in having persistent bracts, a campanulate 5-winged calyx and a style with glandular indumentum. A detailed morphological description, photographic illustration, and distribution of the new species are presented.
Keywords: Arunachal Pradesh; Himalaya; flora of India; morphology; new taxon.
Momang Taram, Dipankar Borah, Ojar Taku, Hui Tag.