Dendrobium chapaense Aver.

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 : 214-215

15. Dendrobium chapaense Aver.

Rheedea 16: 3, figs 2, 3c. (2006). — Zhu Guanghua et al., Flora of

China 25: 391 (2009).

Dendrobium meghalayense C.Deori et al. , Rheedea 16: 55, figs 1, 2k-o (2006), non Y. Kumar & S. Chowdhury (2003), syn. nov.

Dendrobium jaintianum Sabap., Indian Journal of Forestry 30: 371 (2007), syn. nov.

Dendrobium tamenglongense Kishor et al. , Nordic Journal of Botany 32 (2): 151 (2013), syn. nov.

TYPUS. — N Vietnam. Lao Cai Prov., Sa Pa Distr. Vic. of Sa Pa town mt., forest at about 1500-2000 m., 25.XI.2005 , L. Averyanov , P. K. Loc , HAL 8321 (holo-, LE).

HABITAT, PHENOLOGY AND CONSERVATION STATUS. — Epiphyte on tall trees and lithophyte on mossy cliffs in primary and secondary humid broad-leaved montane forests on granite and quartzite, particularly on mountain tops. (1500) 1800-2400 m. Fl. October-November.Locally common. Expected IUCN Red List status – EN.

DISTRIBUTION. — Vietnam (Lai Chau, Lao Cai). NE India , S China .

MATERIAL EXAMINED. — Vietnam. Lai Chau, Phong Tho , HAL 10637 ( HN, MO); Lai Chau, Tam Duong, HAL 10202, HAL 10326 ( HN, LE, MO); Lao Cai, Sa Pa, Hoang Lien Range, N. A . Duc et al., HL 131 ( HNU, LE); Lao Cai, Sa Pa area, cult. in Dalat city, 25.XI.2015, L . Averyanov s.n. ( LE photo) .

Beside scientific herbarium collections many plants come into private cultivation from tourist areas of northern Vietnam where the species is not rare. Collectors and precise original localities of such plants remain unknown.

DESCRIPTION

Stems cylindric, fleshy,10-25(30)cm long, 0.5-1 cm in diameter, of many nodes. Leaves lanceolate to oblong lanceolate, 4-6(8) cm long, 0.7-1.2 cm wide.Inflorescences 1-3(4), 1-2.5 cm long, each with 1-3(5) flowers; floral bracts ovate, acute, 5-12 mm long. Pedicel and ovary 2-3 cm long, slender, circular in section. Flowers odorless, not widely opening, 1.5-2 cm across. Sepals and petals white; median sepal narrowly ovate, acute to acuminate, 1.4-1.6 cm long, 5-6 mm wide; lateral sepals triangular, 2-2.5 cm long, form spur-like, straight, cylindrical white mentum 1-1.6 cm long; petals, lanceolate, narrowing toward the base, acute to acuminate, 1.5-1.8 cm long, 3-4 mm wide. Lip orange-pink to yellow-orange, broadly obovate rhombic, 2-2.5 cm long, 1.6-2.5 cm wide, 3-lobed, disc with low, orangered keel dissected into 3 warty lines at the base of midlobe; side lobes half circular; median lobe triangular ovate, acute, 3-7 mm long, 4-6 mm wide, strongly undulate and irregularly denticulate along the margin. Column orange, 2.5-3.5 mm tall; anther cap white. Capsule narrowly ovoid, 1.5-2 cm long ( Figs 3I ; 4 A-C).

REMARK

The species is close to D. longicornu Lindl. , which is fairly common in northern Vietnam, eastern India and southern China. From this widespread species D. chapaense distinctly differs in having usually shorter and thicker stems, smaller flowers,shorter spur and in distinctly 3-lobed orange-red lip with acute triangular median lobe.Probably, this species is an endemic element of the SE Himalayas, embracing highlands of north-eastern Vietnam, south of Yunnan, Manipur and Meghalaya.

Figures

FIG. 3. — A, Dendrobium multilineatum Kerr (LA-VN 256); B-D, Dendrobium williamsonii Day & Rchb.f. (CPC 24290); E, F, D. cariniferum: Rchb.f.; E, VH 2256a; F, HLF 5500a; G, H, D. longicornu Lindl. (CPC 5378); I, D. chapaense Aver. (N.A.Duc et al., HL 131). Photos: A, N. S. Khang; B-H, L. Averyanov; I, N. A. Duc.

FIG. 4. — A-C, Dendrobium chapaense Aver. (25.XI.2015, L.Averyanov s.n.); D, E, D. ochraceum De Wild.; D, CPC 3576; E, HAL 8056; F, G, D. trankimianum T.Yukawa; F, Hon Giao, J.Ponert et al., s.n.; G, L.Averyanov s.n., 2005; H, D. senile E.C.Parish & Rchb.f. (L.Averyanov s.n., IV.2011); I, D. trigonopus Rchb.f. (CPC 1141a). Photos: A-E, G-I, L. Averyanov; F, J. Ponert.