Nanhaia is a genus of flowering plants belonging to the family Fabaceae.[1] Its native range is Southern China to Northern Vietnam.
Nanhaia species are twining vines, sprawling or scrambling among rocks and scrub. Their stems are green or brown. Their leaves are evergreen and generally have 4–16 paired leaflets plus a terminal leaflet. The leaflets are long by wide. The erect or pendant inflorescence is a panicle, long, frequently composed of several leafy lateral racemes. The individual flowers are long and have the general shape of members of the subfamily Faboideae. The standard petal is long by wide, white, cream or pink in colour, with a green nectar guide. The wing petals are about the same length as the keel at long by wide, free from the keel and with short basal claws. The keel petals are long by wide with a claw up to long. Nine of the stamens are fused together, the other is free; all curve upwards at the apex. The flat seed pods are long by wide, brown and hard when dry, splitting to release their 2–10 seeds.
The genus Nanhaia was established in 2019 following a molecular phylogenetic study which showed that two species that Anne M. Schot had placed in Callerya in 1994 did not belong with the type species of that genus. The genus name is based on the Chinese name for the South China Sea between China and Vietnam, .
Nanhaia is placed in the tribe Wisterieae, where it forms a clade with the genus Wisteriopsis. Nanhaia has larger flowers (usually over rather than under long) and densely hairy rather than hairless ovaries.
, Plants of the World Online accepted two species:
Nanhaia species are native to south-central and southeast mainland China, Hainan and Vietnam.