Dendrobium dekockii

Dendrobium dekockii J.J.Sm., Bull. Jard. Bot. Buitenzorg, sér. 2, 2 (1911) 14; Nova Guinea 12, 1 (1913) 68, t. 18, fig. 54.

Type: Kock, de 47 (holo BO).

Erect to semipendulous, tufted, epiphyte, 2-8(-15) cm high. Roots 0.5-1.25 mm diameter (especially when moist). Rhizome usually very short, occasionally elongated and branching. Pseudobulb 0.2-2.5(-5) by 0.1-0.6 cm, polymorphous-ovoid, globose, fusiform, clavate, cylindrical or moniliform, often markedly constricted at central node, apex 1-4-leaved. Leaves 0.5-6 by 0.1-0.35 cm, erect to spreading, linear to lanceolate, apex subacute, mucronate; sheaths finely warty. Inflorescences terminal, mainly on leafy stems, 1-2(-3)-flowered, subsessile; bracts broadly ovate, apiculate to acuminate. Flowers 1.4-2.8 cm long (rarely to 3.2 cm long-usually at high altitude when epiphytic on Cyathea ), erect to suberect, widely opening, long lasting. Median sepal 5-14 by 2-4.5(-5.5) mm, lanceolate to elliptic, acute. Lateral sepals 11-30 by 3-6.5(-7.5) mm, obliquely triangular, sometimes markedly falcate; basal fused part 3-6 mm long, subconical; mentum total length 9-21 mm, tip usually bilobed. Petals 4-12 by 1-2.5(-3.5) mm, narrowly linear to subspathulate-elliptic, subacute to acuminate. Lip 12-27 by 2-4 mm, subtrilobate, linear-oblanceolate, adnate to column foot at base, upper margins incurved, apex shortly cuspidate to triangular-acuminate, erect to abruptly recurved, margins erose. Column 2-3.5 mm long; foot 9-21 mm long; anther 1.5-2.5 mm broad; pollinia 1-1.5 mm long. Ovary 5-ribbed, sometimes the 2 lateral ribs quite indistinct; pedicel and ovary 10-28 mm long. Fruit 14 by 11.5 mm long, obovoid becoming ellipsoid to subglobose.
(after Reeve & Woods, 1989).

Colours: Roots purplish pink. Leaves green to dark purple, occasionally red. Flower bright orange to orange red, anthers similarly coloured. Fruit green, purplish or reddish.

Habitat: Epiphyte in alpine shrubberies and forest margins, often on Dacrycarpus, Altitude (2300 to) 2700 to 3800 m.

Flowering time in the wild: Throughout the year, perhaps with a peak from June to September.

Distribution: New Guinea.

Distribution in New Guinea: Papua (Mt. Carstenz, Mt. Doorman, Mt. Wilhelmina, Mt. Goliath); Papua New Guinea (West Sepik, Enga, Southern Highlands, Western Highlands, Simbu, Eastern Highlands, Madang, Morobe and Central Provinces).

Map: DEKOCMAP.JPG [Dendrobium dekockii J.J.Sm., distribution map, redrawn from T.M. Reeve & P.J.B. Woods, Notes Roy. Bot. Gard. Edinburgh 46 (1989) 284, map 3.]

Notes: This alpine species, often found growing together with Dendrobium brevicaule, is distinguished from that species by its smaller size and the shorter, more erect flowers which do not have purplish black anther caps. Dendrobium dekockii occurs on most of the high mountains in New Guinea and is quite abundant in some localities as on Mt. Wilhelm, Papua New Guinea, where it grows epiphytically on stunted Dacrycarpus trees at c. 3500 m near the lower lake.

In addition to a large range in pseudobulb shape the plant form varies considerably from those with short lanceolate leaves to others with long narrow linear leaves. The flowers vary somewhat in shape as well as size.

Dendrobium dekockii, being an alpine member, has proved a rather difficult species to establish and to cultivate. Although some success has been achieved in growing this species in the Highland Orchid Collection at Laiagam, Papua New Guinea, it has seldom flowered in cultivation. In nature the plants are usually quite floriferous and the bright orange flowers are a striking sight as they are often set amongst a very dark background of black epiphytic mosses which commonly clothe the branches of alpine Dacrycarpus and other host trees (after Reeve & Woods, 1989).

Cultivation: Cool growing epiphyte, prefers light position.