Dendrobium senile E.C.Parish & 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 : 216

18. Dendrobium senile E.C.Parish & Rchb. f.

The Gardeners’ Chronicle and Agricultural Gazette 1865: 434 (1865). — Gagnep., Flore générale de l’Indo-Chine 6 (2): 223 (1933). — Seidenf., Opera Botanica 83: 42, fig. 20, table 4c (1985); 114: 227 (1992). — Newman et al., A Checklist for the Vascular Plants of Lao: 265 (2007). — Schuiteman et al., Nordic Journal of Botany 26: 287 (2008). — Aver., Taiwania 57 (2): 131, fig. 5 g (2012).

TYPUS. — P eninsular Myanmar. Burma: Shway-gyen distr. , Tenasserim, Parish 135 (lecto-, K [ K000943932 ], designated here) .

HABITAT, PHENOLOGY AND CONSERVATION STATUS. — Epiphyte on tall trees in primary evergreen broad-leaved humid mossy forests on rocky highly eroded crystalline limestone. 900-1200 m. Fl. March- May. Very rare. Expected IUCN Red List status – EN.

DISTRIBUTION. — Laos (Bolikhamxai, Champasak, Vientiane, Xiangkhoang). Vietnam (Dien Bien). Myanmar, Thailand.

MATERIAL EXAMINED. — Laos. Bolikhamxai, sine coll., sine loc. ( NUOL cult. OL1111 ); Champasak, Bolaven, Paksong, E . Konstantinov AL 173 / K400 ( LE photo); Vientiane, Phou Khao Khouay National Protected Area , 9.XII.2015, L . Averyanov et al., AL 158 ass. ( LE photo); Vientiane, sine coll., sine loc. ( NUOL cult. OL1214 ); Vientiane, Phu Khao Khouai, A . D.Kerr 2225, 2229 ( C); Xiangkhoang , Tatom, Chieng Kwang, A. F.G . Kerr 960 ( P [ P00408210 ]) .

Vietnam. Dien Bien, L.Averyanov CPC s.n., XII.2010, 12.IV.2011 ( LE photo).

DESCRIPTION

Stems narrowly fusiform, distinctly flexuose, 5-15 cm long, 0.5-1 cm in diameter, of few nodes, leaves and leaf sheaths densely haired by long white hairs. Leaves, lanceolate to oblong, 4-8 cm long, 0.7-1 cm wide. Inflorescences 1-3(4), each with 1-2(3) flowers. Pedicel and ovary green, 2.5-4 cm long. Flowers widely opening, 2.5-3 cm across, golden yellow, disc yellow-green, base of side lobes red veined. Sepals and petals subsimilar, narrowly ovate, 1.8-2.2 cm long, 8-10 mm wide, petals little wider, sparsely setose. Lip obovate, almost entire to indistinctly 3-lobed, as long as sepals, 1. 5-2 cm wide, clawed at the base; disc papillose to verruculose without distinct keels. Mentum very short, insignificant, broadly conical, 2.5-4 mm long and broad. Column yellow, 3 mm tall; anther cap yellow, conical, truncate, papillose, 2.5 mm tall ( Fig. 4H ).

REMARK

This species has a very isolated position in the section with its yellow flowers and dense pubescence of long white trichomes. Recent molecular phylogenetic studies also supported its isolated position in the genus and indicates it probably needs to be removed from section Formosae to section Dendrobium ( Xiang et al. 2013; Schuiteman & Adams 2014; Takamiya et al. 2014).

Figures

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.