Vietnam, Quang Binh Prov., Quang Ninh Distr., Truong Son municipality, around Long Son village at 17°17′51″N 106°26′49″E.
Secondary broad-leaved forest on steep slopes of highly eroded karst limestone hills composed with gray solid marble limestone along Long Dai River, at elevation about 30 m a.s.l.
Herbaceous vine to 10 m long in open road cut, Flowers light violet. Very common.
HAL 11549 14 April 2008 photo Coll.: L.Averyanov, P.K.Loc, N.T.Vinh, N.S.Khang