Dendrobium putnamii

Dendrobium putnamii A.D.Hawkes & A.H.Heller, Lloydia 20 (1957) 122 (nom. nov.).

Basionym: Dendrobium coerulescens Schltr.

Small creeping or tufted (if exposed) epiphyte, 1-3 cm high, usually forming a loose mat. Roots c. 0.5 mm in diameter. Rhizome usually distinct, to 1.5 cm long. Pseudobulbs 0.2-1 by 0. 1 5-0.4 cm, 2-3-noded, crowded or more commonly to 1.5 cm apart, set obliquely or erect on rhizome, fusiform, ovoid or spherical, sometimes slightly curved, with 1-3 (usually 2) terminal leaves. Leaves 0.25-1.2(-1.8) by 0.1-0.25 cm, spreading to suberect, lanceolate to linear, usually curved, green to purplish red, sometimes somewhat punctate apex mucronate, attenuated near base; sheaths membranous. Inflorescences terminal, 1(-2)-flowered, subsessile, produced infrequently; bracts c. 4 mm long, ovate, membranous, apex apiculate to acuminate. Flowers 1.1-1.5 cm long lasting several months. Median sepal 4.5-7.5 by 2 mm lanceolate, apiculate to shortly acuminate. Lateral sepals 9-14 by 2.5 mm obliquely lanceolate, apiculate to acuminate; basal fused part c. 2.5 mm long, cylindrical to subconical; mentum total length 6.5-8 mm, tip obtuse. Petals 4-7.25 by 1.25-2 mm, narrowly oblanceolate, acute to acuminate. Lip 7.5-11.5 by 1.5 mm simple to indistinctly trilobulate, linear, adnate to column foot at base, apical part free, margins incurved embracing column, cross-ridge absent, apex triangular acute, straight or slightly deflexed. Column dark blue, 2 mm long; foot 6.5-8 mm long; anther 1.5 mm broad, pollinia 1.2 mm long. Ovary triangular in cross-section; pedicel and ovary 7-l0 mm long. Fruit not observed.
(after Reeve & Woods, 1989).

Colours: Flowers pale blue, sometimes tinged violet and apices of sepals tinged orange; lip pale blue, apex orange to orange-red; column dark blue.

Habitat: Epiphyte forming large mats on trunks and side branches of trees. Altitude 800 to 3000 m.

Flowering time in the wild: September, November.

Distribution: New Guinea.

Distribution in New Guinea: Papua New Guinea (Sandaun, Enga, Western Highlands and Eastern Highlands Provinces).

Map: PUTNAMAP.JPG [Dendrobium putnamii A.D.Hawkes & A.H.Heller, distribution map, redrawn from T.M. Reeve & P.J.B. Woods, Notes Roy. Bot. Gard. Edinburgh 46 (1989) 287, map 10.]

Notes: Schlechter found this species, one of the very few blue flowered orchids, once only and his single specimen had been collected with a solitary flower. The low altitude of c. 800 m recorded for his collection seems odd as more recent collections have all been from 2000 m and above. Assuming that this is a plant of cooler altitudes one might guess that Schlechter's collection may have been from a cold air pocket in its station in the Torricellis.

In its creeping habit Dendrobium putnamii is not unlike Dendrobium parvulum but differs in its narrower, linear-lanceolate not ovate leaves and in its triangular ovary.

Cultivation: According to Reeve & Woods this desirable little species is easy to grow but is reluctant to produce flowers, which even seems to be the case in nature.
(largely after Reeve & Woods, 1989)