Dendrobium bellatulum Rolfe

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

1. Dendrobium bellatulum Rolfe

The Journal of the Linnean Society (Botany) 36: 10 (1903); Botanical Magazine 18: table 7985 (1904). — Gagnep., Flore générale de l’Indo-Chine 6 (2): 226, fig. 19, 6-8 (1933). — Seidenf., Opera Botanica 83: 103, fig. 60, table 13b (1985); 114: 210, table 13c (1992). — Aver., Identification Guide to Vietnamese Orchids: 183 (1994). — P.H.Ho, An Illustrated Flora of Vietnam 3: 826, fig. 11055 (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).

TYPUS. — SW China. Yunnan: Mengtze 5000 ft., Henry 11109 (holo-, K [ K000943750 ]) .

HABITAT, PHENOLOGY AND CONSERVATION STATUS. — Epiphyte on tall trees in primary and secondary, closed and open broad-leaved, mixed and coniferous forests, particularly on ericaceous trees on mountain tops. [phone](2000) m. Fl. December-April. Locally common. Expected IUCN Red List status – EN.

DISTRIBUTION. — Laos (Champasak), Vietnam (Dak Lac, Kon Tum, Lam Dong, Ninh Thuan). NE. India, Myanmar, S. China, Thailand. MATERIAL EXAMINED. — Laos. Champasak, Bolovens, Sedone, A.D.Kerr 1645 (C).

Vietnam. Dak Lac, Krong Bong, Chu Yang Sinh mt., VH 6155 ( HN, MO); Kon Tum, Dacuy, L.Averyanov et al., LX-VN 2214 ( HN, LE); Kon Tum, Dak Gley, VH 2297 ( HN, P [ P 00386129], MO); Kon Tum, Konplong, Mang Den, L.Averyanov et al., LX-VN 2282 ( HN, LE); Kon Tum, L.Averyanov et al., LX-VN s.n. anno 1985 ( LE photo); Lam Dong, Dalat, CRST 13 ( P [ P 00386139]), Evrard 937 ( P [ P 00386133]), 1798 ( P [ P 00386134]), 1880 ( P [ P 00386135]), 1913 ( P [ P 00386136]), 1962 ( P [ P 00386137]), 2168 ( P [ P 00386138]), A.D.Kerr s.n. ( C), L.Averyanov HAL s.n. 2004 ( LE photo); Lam Dong, Lac Duong, Bi Dup mt., VH 2693 ( HN, LE, MO), HLF 5202 ( HN); Lam Dong, Langbian, Chevalier 30699 ( P [ P 00386130, P 00386131]); Lam Dong, 8.5 km to S from Dalat, VH 2623a ( HN, LE photo); Lam Dong, 14 km to NNW from Dalat, VH 2566 ( HN, LE, MO), VH 2567 ( HN, LE); Ninh Thuan, Ninh Hai, Nui Chua mt., HLF 4318 ( HN, MO); Vietnam, sine loc., Eberhardt 69 B ( P [ P 00386132]).

DESCRIPTION

Stems erect, clavate to obovoid, 2-5(7) cm long, 1-1.5 cm in diameter, with 2-5(6) nodes. Leaves 2-4, ovate to oblong, 1.5- 4 cm long, 0.6-1.4 cm wide, shortly black hairy, unequally bilobed at apex. Inflorescence 1(2), 1-2(3) flowered, subterminal on mature stems; peduncle and rachis 2-6 mm long; floral bracts ovate, membranaceous, 5-8 mm long. Pedicel and ovary pale greenish, 1-2 cm long. Flowers widely opening, 2.5-3 cm across, white, lip red with yellow epichile, rarely entirely red. Sepals and petals subsimilar, narrowly ovate, acute, 1.5-2 cm long, 5-8 mm wide, lateral sepals oblique; mentum broadly conical, 1-1.5 cm long. Lip pandurate, 2-2.6 cm long, 1.2- 1.6 cm wide; lateral lobes ovate, erect; median lobe 2-lobed, bent down; disc fleshy, with 5 indistinct rugose to papillose keels. Column pink, 2-3 mm tall; anther cap broadly conical, papillose ( Fig. 1A, B ).

REMARKS

Remarkable forms of this species with entirely red lip lacking any yellow on epichile occasionally occur in highland Pinus kesiya woodlands around Dalat city area in Lam Dong province of the southern Vietnam ( Fig. 1B ).

Some cultivated plants originated from Thailand develop pseudobulbs to 7 cm long consisting of 6 (or more) nodes. Such plants do not differ in any other character.

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.