Laos, Khammoune prov., Boualapha distr., Nong Seng village, Chanh Daeng mountain, around point 17°31′11.1″N, 105°46′41.4″E.
Primary dry evergreen and semideciduous broad-leaved forest on very steep rocky slope near karstic hill top composed with solid, marble-like highly eroded limestone at 400-600 m a.s.l.
Woody vine to 10 m long among exposed rocks near mountain top. Flowers dark purple-violet. Common.
11 May 2018, L. Averyanov, Khang Sinh Nguyen, T. Maisak, Littideth Xaiyavongsa, Siphanom Keovankham, AL 990.