N. Vietnam, Thai Nguyen prov., Dong Hy distr., Tan Long municipality, vicinities of Mo Ba village (21°46′26′'N, 105°52′25′'E). Primary wet broad-leaved evergreen closed forest (with Burettiodendron hsienmu as a main dominant) on remnant highly eroded limestone ridge at elev. 400-550 m a.s.l. Terrestrial and lithophytic herb in wet rocky places. Leaves deep green above, deep purple-violet below, petiole deep brown, nearly black. Flowers light yellowish-green. Abundant at elev. 400-530 m a.s.l.