Dendrobium wattii

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 : 209-210

10. Dendrobium wattii (Hook.f.) Rchb.f.

The Gardeners’ Chronicle 2: 724 (1888). — Gagnep., Flore générale de l’Indo-Chine 6 (2): 244 (1933). — Seidenf., Opera Botanica 83: 113, figs 70, 71 (1985); 114: 212, fig. 136 (1992). — Aver., Identification Guide to Vietnamese Orchids: 181 (1994). — P.H.Ho, An Illustrated Flora of Vietnam 3: 828, fig. 11063 (2000). — Aver. & Averyanova, Updated Checklist of the Orchids of Vietnam: 31 (2003). — Newman et al., A Checklist for the Vascular Plants of Lao: 266 (2007). — Schuiteman et al., Nordic Journal of Botany 26: 315 (2008). — Zhu Guanghua et al., Flora of China 25: 392 (2009).

Dendrobium cariniferum Rchb. f. var. wattii Hook. f., Botanical Magazine 109: table 6715 (1883).

Dendrobium evrardii Gagnep. , Bulletin du Muséum national d’Histoire naturelle, 2 ème série, 2 (2): 235 (1930). — Gagnep., Flore générale de l’Indo-Chine 6 (2): 230 (1933).

TYPUS. — NE India. On ascent to Seriphari , Munipore, Watt 5944 (holo-, K [ K000363084 ]) .

HABITAT, PHENOLOGY AND CONSERVATION STATUS. — Epiphyte on tall trees in primary and secondary evergreen broad-leaved, mixed and coniferous humid mountain forests on granite and shale, particularly on very steep rocky slopes and on mountain tops, often in ericaceous thickets in the cloud zone. (900) 1000-2400 m. Fl. September-November, February-March. Rare. Expected IUCN Red List status – EN.

DISTRIBUTION. — Vietnam (Kon Tum, Lam Dong, Ninh Thuan). NE. India, Myanmar , N. Thailand , S. China .

MATERIAL EXAMINED. — Vietnam. Kon Tum, Ngoc Linh peak, VH 564 ( HN, LE, MO, P [ P00408310 ]) ; Kon Tum, Ngoc Linh , L. Averyanov s.n., anno 1995 ( LE photo) ; Lam Dong, Dalat area , L. Averyanov s.n., anno 1995 ( LE photo) ; Lam Dong, Dalat area , L. Averyanov s.n., XI.2013 ( LE photo) ; Lam Dong, Dalat area , HAL 8630 ( LE, LE photo, MO) ; Lam Dong, Dalat , CRST 70 ( P [ P00408311 ]) , Tixier drawing 4/59 ( P) ; Lam Dong, Langbian , Evrard 389 ( P [ P00408313 ]) , Grillet 115 ( P [ P00408312 ]) ; Lam Dong, massif du Bi-Doup, prov. du Haut Donaï, Poilane 31050 ( P [ P00407643 , P00407644 ]) ; Ninh Thuan, Ninh Hai, Nui Chua mt. , HLF 4438 ( HN, LE, MO) .

DESCRIPTION

Stems reed-like, cylindric, (5)10-50(60) cm long, 0.5-1 cm in diameter, of few to many nodes. Leaves oblong lanceolate, (3)4-8(10) cm long. Inflorescences 1-2(3), each with 1-3 flowers; floral bracts ovate, acute, 5-8(12) mm long. Pedicel and ovary white, 2.5-3.5(4) cm long. Flowers odorless, widely opening, spreading, 3.5-5 cm across, white; lip side lobes with yellow to orange stripes, disc yellow, orange or orange-red. Sepals subsimilar, triangular narrowly ovate, acute to shortly acuminate, 2.2-3 cm long, 0.8-1.2 cm wide. Petals rhomboid broadly obovate, bluntly rounded and shortly mucronate, 2.2-3(4) cm long, 1.5-2(2.5) cm wide, little longer and twice broader than sepals. Mentum narrow, cylindric, straight, spur-like, 1.5-2(2.2) cm long. Lip obtriangular broadly obovate, 3-lobed, 2-3 cm long, 1.8-2.2(3) cm wide; side lobes, half circular, erect, embracing the column; median lobe broadly obovate to rectangular, 8-10(12) mm long and wide, narrowing to base, irregularly denticulate and undulate along margin, truncate and shortly apiculate at apex; disc with 3(5) low indistinct parallel keels extending from base of lip to base of median lobe. Column white, 7-9 mm tall; anther cap white, cubic, apically truncate 3-4 mm tall and wide ( Fig. 2F, G ).

REMARKS

This species is close to D. infundibulum and D. multilineatum , but differs in the somewhat smaller flowers and the lip having a broadly obovate, sometimes indistinctly clawed, irregularly denticulate, usually with a shortly apiculate median lobe.

Some early authors expressed opinion that this species is close to D. longicornu and D. infundibulum and may be a natural hybrid of these species ( Seidenfaden 1985). Recent field observations do not support this supposition. In eastern Indochina the areas of both mentioned species do not overlap, making their natural hybridization hardly credible.

Figures

FIG. 2. — A, Dendrobium kontumense Gagnep.(L.Averyanov s.n., X.2005);B, D. roseiodorum Sathap.,T.Yukawa & Seelanan (L.Averyanov s.n., X.2005);C, D, D. daklakense Tich,Schuit. & J.J.Verm.; C, Vo Van Cong, s.n., XI.2015; D, V.Q.Binh & L.Averyanov, s.n., 7.XI.2014; E, D. infundibulum Lindl. (L.Averyanov s.n., Thailand, Chiangmai, 2002); F, G, D. wattii (Hook.f.) Rchb.f.; F, L.Averyanov s.n., XI.2013; G, HAL 8630; H, D. multilineatum Kerr (LA-VN 256). Photos: A-G, L. Averyanov; H, N. S. Khang.