Dendrobium christyanum Rchb.

Averyanov, Leonid V., Ponert, Jan, Nguyen, Phi Tam, Duy, Nong Van, Khang, Nguyen Sinh & Nguyen, Van Canh, 2016, A survey of Dendrobium Sw. sect. Formosae (Benth. & Hook. f.) Hook. f. in Cambodia, Laos and Vietnam, Adansonia 38 (2), pp. 199-217 : 204-205

2. Dendrobium christyanum Rchb. f.

The Gardeners’ Chronicle 1: 178 (1882). — Gagnep., Flore générale de l’Indo-Chine 6 (2): 239 (1933). — Seidenf., Opera Botanica 83: 105, fig. 61, table 13c (1985); 114: 210, fig. 133 (1992). — Aver., Identification Guide to Vietnamese Orchids: 183 (1994). — P.H.Ho, An Illustrated Flora of Vietnam 3: 826, fig. 11056 (2000). — Aver. & Averyanova, Updated Checklist of the Orchids of Vietnam: 26 (2003). — Newman et al., A Checklist for the Vascular Plants of Lao: 262 (2007). — Schuiteman et al., Nordic Journal of Botany 26: 280 (2008). — Zhu Guanghua et al., Flora of China 25: 391 (2009). Dendrobium margaritaceum Finet , Bulletin de la Société botanique de France 50: 379, table 14, fig. 31-38 (1903). — Gagnep., Flore générale de l’Indo-Chine 6 (2): 226 (1933).

Dendrobium fuerstenbergianum Schltr., Repertorium specierum novarum regni vegetabilis 3: 277 (1907). — Seidenf., Opera Botanica 83: 106, fig. 62, table 13d (1985).

Dendrobium sinense Tang & F.T.Wang, Acta Phytotaxonomica Sinica 12: 41 (1974).

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. Locally common. Expected IUCN Red List status – EN.

DISTRIBUTION. — Vietnam (Khanh Hoa, Kon Tum, Lam Dong, Nghe An, Ninh Thuan). Thailand , S. China .

MATERIAL EXAMINED. — Vietnam. Khanh Hoa, Nhatrang, Chevalier 4080 ( P [ P00386241 ]) ; Kon Tum, Ngoc Linh mt. , VH 110 ( HN, LE, MO, P [ P00386246 ]) , VH 127 ( HN, LE, MO, P [ P00386245 ]) , VH 563 ( HN, LE, MO, P [ P00386244 ]) , VH 950 ( HN, LE, P [ P00386243 ]) ; Kon Tum, Ngok Peng Oei, Dak Gley, Poilane 32931 ( P [ P00386239 ]) ; Kon Tum, Sa Thay , P. K.Loc s.n., anno 2003 ( LE photo) ; Lam Dong, Bi-Doup, Poilane 30229 ( P [ P00386240 ]) ; Lam Dong, Dalat area, Petrov s.n., IV.2013 ( LE photo) ; Lam Dong, Haut Donaï, Lang Bian, Vernet 2 ( P [ P00386242 ]) ; Nghe An, Ky Son, Phu Xai Lai Leng mt. , CPC 6038 , CPC 6391 ( CPC Herbarium, LE, LE photo) ; Ninh Thuan, Ninh Hai, Nui Chua mt. , HLF 4614 ( HN, MO) .

DESCRIPTION

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 white, 4-5 mm tall; anther cap white, conical, truncate ( Fig. 1C, D ).

REMARK

This species was observed in the past as an abundant plant on many tops of the Ngoc Linh and Phu Xai Lai Leng mountains. 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.

Figures

FIG. 1. — A, B, Dendrobium bellatulum Rolfe; A, VH 2566; B, VH 2567; C, D, D. christyanum Rchb.f.; C, VH 950; D, CPC 6038; E, D. scabrilingue Lindl. (Konstantinov 29); F, G, D. suzukii T.Yukawa; F, Duy s.n., III.2014; G, L.Averyanov s.n., XI.2013); H, D. draconis Rchb.f. (HLF 7347); I, D. kontumense Gagnep.(LA-VN 21a). Photos: A-D, G-I, L. Averyanov; E, E. Konstantinov; F, N.V. Duy.