Acanthaceae Xylacanthus laotica Aver. et K. S. Nguyen
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.
Shrub or treelet 2-3 m tall on open rocky slope near mountain top. Very common.
11 May 2018, L. Averyanov, Khang Sinh Nguyen, T. Maisak, Littideth Xaiyavongsa, Siphanom Keovankham, AL 1023.