Orchids of New Guinea

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Dendrobium soriense

Dendrobium soriense Howcroft, Orchadian 11 (1996) 580, fig. 1 & 2.

Type: Tkatchenko & al. 79016 (LAE holo).

Synonyms:

Durabaculum soriense (Howcroft) M.A.Clem. & D.L.Jones, Orchadian 13 (2002) 489

A medium-sized epiphytic herb similar to Dendrobium conanthum. Rhizomes short, cylindrical. Pseudobulbs slender, cane-like, clustered, terete, many noded, slightly dilated towards the base, 100 cm or more tall, c. 1.5 cm diameter towards base. Sheaths tubular. Leaves oblong-ovate, 4-9 by 2-5 cm or larger, minutely unequally bilobed, leathery. Inflorescences borne towards the apical part of the stem, racemose, spreading to arcuate, about 25 cm or more long, bearing c. 9-20 flowers; peduncle slender, terete. Pedicel approximately at 90 degrees to ovary, 3.5-3.7 cm long, ovary c. 0.6 cm long. Flowers mostly erect, c. 4 cm long. Dorsal sepal upright to reflexed, spirally twisted, narrowly oblong-lanceolate, c. 2.3 cm by 7 mm, margins undulate. Lateral sepals reflexed or not, spirally twisted, oblong-lanceolate, 3.2 cm long along basal margin, 2.2 cm long along top margin, 9 mm wide at base, c. 6 mm wide at midsection, margins undulate, apex acute; mentum conical, prominent. Petals linear-spathulate, 2.7 cm long, 7 mm wide towards apex, spirally twisted once to twice, acute or obtuse. Lip 3-lobed, elliptic in outline, c. 2.8 cm by 15 mm when flattened, with a callus of five keels, the three middle ones prominently raised and terminating on mid portion of the midlobe; lateral lobes narrowly oblong-elliptic, 2 cm by 5 mm, rounded in front, overlapping base of mid-lobe, with verruculose venation and erose margins towards apices; midlobe slightly recurved, oblong-ovate, 0.9-l.O cm long, 8 mm wide, margins not erose, apex subacute. Column 0.6-0.7 cm long, 4 mm wide, with 3-4 teeth on short broad stelidia on each side of the clinandrium; column foot c. 1.3-1.4 cm long, at c. 120 degrees angle from axis of column. Anther cap apically notched.
(after Howcroft 1996).

Colours:

Flower pale yellow brown flushed pink with a violet veined lip.

Habitat:

Epiphyte on trees along rivers through mangrove forests over hanging the water. Altitude 0 m.

Distribution:

Admiralty Islands (endemic).

Distribution New Guinea:

Papua New Guinea (Sed Island and Sori Island near Manus island).

Map: Dendrobium soriense Howcroft, distribution map.

Cultivation:

Warm growing epiphyte.

Flowering time in the wild:

Not recorded.

Classification:

Family Orchidaceae
Subfamily Epidendroideae
Tribe Dendrobieae
Subtribe Dendrobiinae
Genus Dendrobium
Section Spatulata
Species Dendrobium soriense

Notes:

Dendrobium soriense Howcroft is in many ways similar to Dendrobium conanthum Schltr., but may be distinguished by its 5 keels on the lip, of which 3 extend to the midlobe. In D. conanthum only a single keels extends to the midlobe.