Orchids of New Guinea

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Dendrobium crassilabium

Dendrobium crassilabium P.J.Spence, Telopea 10, 2004 782, fig. 1.

Type: Sydney cult. s.n. (Spence & Clements 8190)(holo NSW; iso CANB, Herb. P. Spence 37).

Epiphyte, erect or somewhat spreading, 12 to 28 cm tall. Rhizome abbreviated, to 0.02 cm long. Roots threadlike, glabrous. Stems pseudobulbous, cylindrical, with 1—3 leaves, 0.3—0.8 cm diam.; base slightly attenuate, finely furrowed lengthwise. Leaves (sub-)terminal, spreading at an c. 45°, lanceolate to elliptic, 12—18 by 3—5 cm; base cuneate; apex acuminate. Inflorescence (sub)terminal, shorter than the leaf, 4—14-flowered, 6—10 cm long; peduncle thin, 2—4 by 0.18 cm; rachis 4—8 cm long; bracts at the base with c.15° angle to the rachis, ovate or elliptic, glabrous, 3— 4mm long, with shortly acuminate apex. Flowers at a c. 45° angle to rachis. Lateral sepals slightly falcate, oblong, 1.2 by 0.8 cm; apex cuspidate. Median sepal oblong, 1.4 by 6—0.85 cm; apex apiculate to cuspidate. Petals obliquely lanceolate, c. 1.1 by 0.3—0.4 cm; apex acute or acuminate. Lip 3-lobed, c. 1.5 by 0.7 cm; base a narrow, non- articulate claw; lateral lobes small, spreading, oblong, slightly falcate, 0.3 by 0.25 cm, with obtuse apex; midlobe much larger, porrect, fleshy thick for the section, rigid, transversely elliptic-reniform, cordate to almost quadrangular c. 1.2 by 0.7 cm; median sulcate; apex truncate with a downturned apicule 0.65 cm wide, not exceeding the lateral lobes; callus ligulate, expanded and thickened in front, with abruptly obtuse apex, extending from the lip base to the base of the mid-lobe. Column broadly elliptic, hooded, exceeding the length of the lateral lobes of the lip, 0.8—0.9 by 0.028—0.03 cm wide. Anther hooded, broadly elliptic, glabrous, c. 0.012 by 0.018—0.02 cm; apex slightly truncate. Pedicel slender, 0.8 by 0.2 cm; ovary thick for the size of the flower, almost cylindrical, 0.4—0.6 by 0.34—0.4 cm.
(after Spence 2004)

Colours:

Sepals and petals light apple green to almost olive-green; labellum similar or darker.

Habitat:

Epiphytes exposed to full sun and constant high humidity forming large colonies in humus on trunk and main branches of trees overhanging a river. Altitude 400 m and 2500 m.

Distribution:

Malesia (New Guinea, endemic).

Distribution New Guinea:

Papua New Guinea (Northern and Gulf Provinces).

Cultivation:

Warm to cool growing epiphyte, tolerates exposed potition.

Flowering time in the wild:

August. Specimens of the plant from which the type was collected are reported flowering almost all year round and to last for 2-3 months. Flowering in cultivation in Leiden in November-February.

Classification:

Family Orchidaceae
Subfamily Epidendroideae
Tribe Dendrobieae
Subtribe Dendrobiinae
Genus Dendrobium
Section Latouria
Dendrobium crassilabium

Notes:

Dendrobium crassilabium P.J.Spence differs from the similar Dendrobium subquadratum J.J.Sm. in a.o. the erect habit (versus pendulous), the length of the callus (0.5 versus 1.55 cm), the dimensions of the median sepal (1.4 by 0.85 cm versus 1.4 by 1.35 cm and the length of the pedicel and ovary (1.15—1.2 versus 2 cm).