Dendrobium x yengiliense T.M.Reeve, Orchadian 7 (1982) 137, fig. 7.
Type: Reeve 445 (holo LAE; iso K).
A tufted epiphytic herb, up to 4 cm tall. Roots slender, c. 0.5 mm diameter, tips green. Rhizomes short. Pseudobulbs more or less fusiform, rugose, with c. 8 nodes, 10-36 by 4-7 mm, each new stem with 3-5 leaves near the apex. Leaves ovate-lanceolate, 0.7-2.2 cm by 2-8 mm, acute often mucronate. Inflorescences terminal or subterminal, with 5-12 flowers, arising from both leafy and leafless stems, peduncle and rachis short. Bracts ovate, 3-5 by 2-3 mm, acuminate. Ovary with pedicel c. 1 cm long; ovary not distinctly ribbed. Flowers c. 10 mm long. Dorsal sepal ovate, 4 by 2-2.5 mm, obtuse to minutely apiculate. Lateral sepals c. 9 by 3.5 mm with base fused at front for c. 3 mm; mentum apex obtuse. Petals narrowly oblong to spathulate, 4 by 1.5 mm, acute. Lip oblong-linear, c. 8.5 by 2 mm, with a distinct transverse ridge in the centre, base saccate, apex subacute, slightly recurved. Column typical of the section, c. 2 by 1.5 mm; column foot c. 5 mm long; pollinia c. 0.8 mm long.
(after Reeve, 1982).
Colours: Pseudobulbs brown covered with purplish sheaths which become white with age. Leaves green above, purplish beneath. Flowers pale bluish white with ovary, mentum and lip (except apex) purplish and cross-ridge on lip reddish. Pollinia greyish-green.
Habitat: Epiphyte in mntane forest. Altitude c. 2600 m.
Flowering time in the wild: May.
Distribution: New Guinea (endemic).
Distribution in New Guinea: Papua New Guinea (Enga Province).
Map: XYENGMAP.JPG [Dendrobium x yengiliense T.M.Reeve, distribution map.]
Notes: Dendrobium x yengiliense is a natural hybrid of which Dendrobium leucocyanum is one of the parents. It was discovered by Reeve in the Yengili Valley in 1976. The only other common species of section Pedilonum in this area are Dendrobium alaticaulinum and Dendrobium calyculimentum. These species are quite similar, differing mainly in size, and it is difficult to tell which of them is the second parent. The size of the flowers points to D. alaticaulinum as the probable parent but artificial hybridisation would be required to settle the issue. Flower lengths are as follows: D. alaticaulinum 8-12 mm, D. caliculimentum 14-17 mm, D. leucocyanum 8-11 mm, D. x yengiliense 10 mm.
(after Reeve, 1982).
Cultivation: Cool growing epiphyte. Does well mounted on tree fern slabs.