This research provides a description and illustrations for a new species from the Phong Nha-Ke Bang National Park,
Cynanchum quangbinhense. The distribution, habitat, phenology and conservation assessment for the species are also presented.
The new species differs from closely related species, C. ovalifolium in many characters such as leaf shape, inflorescence type, fewer
and smaller flowers, colour of petals, margins of the corona, and anthers appendages shape, and differs from C. kwangsiense in
having small leaves, umbellate inflorescences, triangular sepals, retuse apex of petals, and plicate margin of corona. Our discovery
raises the known species of this genus in Vietnam to seven. In addition, a key to species of Cynanchum in Vietnam, and notes on
morphological variation of C. officinale are presented in this paper.