Tên Khoa học: Dendrobium christyanum Reichb.f.Tên tiếng Anh: Tên tiếng Việt: Hỏa hoàng; Bạch hỏa hoàngTên khác: Dendrobium margaritaceum Fin.;
Typus. — Thailand. Siam, sine loc., Veitch, Herb. Reichenbach, 32377 (holo-, W). haBitat, phenoLogy and conservation status. — Epiphyte on tall trees in primary and secondary evergreen humid broad-leaved and mixed forests on steep slopes on granite, particularly along mountain edges, often on ericaceous and pine trees. (1000)1500-2400 m. Fl. January-March, August-September.
Expected IUCN Red List status – EN.
Vietnam (Khanh Hoa, Kon Tum, Lam Dong, Nghe An, Ninh Thuan).
Thailand, S. China.
Stems fusiform to cylindrical, (4)5-15(25) cm long, 5-8 mm in diameter, of few to many nodes. Leaves lanceolate to oblong lanceolate, 3-8 cm long, 0.6-1.4 cm wide. Inflorescences 1-2(3), each with 1-2(3) flowers. Pedicel and ovary pale greenish, 1.2-2.5 cm long. Flowers odorless, widely opening, 4-7 cm across, white, disc bright red, usually with contrasting yellow spot in the front on adaxial surface. Sepals triangular ovate, acute, 2.2-3.5 cm long, 0.8-1.4 cm wide; mentum broadly conical, 0.8-1.2 cm long. Petals narrowly obovate to oblong, as long as sepals, as wide as sepals or little wider, acute to shortly apiculate. Lip broadly obovate, pandurate, 3-lobed, 3-5(5.5) cm long, 2.5-3.2 cm wide, side lobes half circular, as long as emarginate, obcordate median lobe; disc with 3(5) low rugose granulose keels. Column
This species was observed in the past as an abundant plant on many tops of the Ngoc Linh and Phu Xai Lai Leng moun-tains. It was also abundant on old trees of Pinus krempfii in the Lang Bian plateau to the west of the Hon Giao Mountains. Presently the species has become rare due to deforestation and extensive collection for the trade.