In the framework of the study of "Flora of Rao An watershed " the Preliminary Checklist of orchids of Son Kim (Rao An and Rao Bun watersheds) and Son Hong (Song Con, Khe Van watersheds) was compiled on the base of exploration field works of 1999-2004 years. During these studies were documented by nearly 100 herbarium voucher specimens 76 species, which belong to 42 genera. Among them 55 (72.4%) species of wide distribution mainly of Himalayan origin, 2 (2.6%) species endemic for Indochinese Peninsula, 4 (5.3%) species endemic for South Chinese- Northern Vietnam floristic province and 15 (19.7%) species endemic to Vietnam. Last group includes local Vietnamese endemics of very restrict distribution. These species (Biermannia calcarata, Dendrobium ochraceum, Epigeneium chapaense, Eria calcarea, E. gagnepainii, E. thao, Gastrodia taiensis, Habenaria tonkinensis, Liparis balansae, L. chapaensis, L. pumila, Micropera poilanei, Phalaenopsis gibbosa, Pholidota guibertiae, Pteroceras simondianum) underline primary aboriginal character of the flora. Spectrum of florogenetic elements outlines flora of studied area as very specific and highly endemic. Largest genera here are Dendrobium (10), Liparis (8), Eria (6) and Bulbophyllum (5 species). Other genera include one or two species. one discovered species (Stereosandra javanica) was new for the flora of Vietnam. According to threat of extinction most orchids in the flora belong to group of LR (27) and VU (40 species). Some species have still uncertain status - DD (5 species). Species of other groups are very rare and need protection. Group of endangered species (EN) includes Dendrobium ochraceum, Micropera poilanei, Phalaenopsis gibbosa. These rare species have large significance in ornamental horticulture, and commercial collecting may be serious factor of their extinction. only one species belongs to critically endangered (CR). This is Stereosandra javanica, very rare saprophytic orchid occurring on low elevation. Limiting factor for this plant may be destruction of its habitat.
Leonid V. Averyanov
Komarov Botanical Institute - Russian Academy of Sience
Phan Kế Lộc
HUN & IEBR, VAST
Nguyễn Tiến Hiệp, Phạm Văn Thế