Phu Tho Prov., Tan Son Distr., Xuan Son Municipality, Du village, Nhon Mountain, around mountain top, point 21°06′51”N 104°57′34”E.
Remnants of primary evergreen primary forest on very steep slopes and cliffs composed with solid highly eroded marble-like limestone at elevation about 600 m a.s.l.
Undershrub to 2 m tall on the rocky top of mountain. Flowers yellowish with purple tint. Occasional.
HAL 12823 19 February 2009 Photo. Coll.: L.Averyanov, P.K.Loc, N.T.Vinh, L.T.Son.