FLORA OF VIETNAM. Elatostema sp. N. Vietnam, Prov. Cao Bang, distr. Tra Linh, municipalite Quoc Toan,. vicinity of Thang Heng and Lung Tao villages near Thang Heng lake. Remnant closed evergreen primary broadleaved forest in foothills of. limestone ridges and mesas near karst lake at 500 m alt. Terrestrial and epilitic herb up to 0.4 m hg on wet open steep rocky. lake slope. Common. No VH 4928  25-27.05.1997. International Botanical Expedition of the U.S.A. National Geographic. Society (grant No 5803-96). . Collectors: L. Averyanov, N.T. Hiep