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ORCHIDACEAE OF HONG KONG.
PART V.
G. A. C. HERKLOTS,
GEODORUM, Jackson.
Leaves
Terrestial herbs with a tuberous leaf bearing pseudo-bulb. few, elliptic, acute, plicate, base sheathing. Flowering peduncle from the side of the base of the pseudo-bulb, stout, erect, sheathed, shorter than the leaves. Flowers crowded in decurved racemes, bracts narrow, membranous, margins involute; sepals and petals similar, conniving, oblong or ovate-oblong, acute; lip superior, sessile on the base or a short foot of the column, as long as the sepals, cymbiform, membranous, margins incurved; base saccate or shortly spurred; disk with or without ridges ending in calli and with a fork- ed basal callus; column short, stout; anthers 2-celled, 2-auricled, from detach- ed portions of the top of the column which adhere to it, pollinia 2, globose, waxy, subsessile on a broad strap or gland.
(Modified from the accounts given in (6) p. 16 and (8) p. 178). DISTRIBUTION :— -A genus of about 10 species only of the Indo-Malayan region, South China and Australia.
GEODORUM DILATATUM, R. Brown.
Ait. Hort. Kew. ed. 2 v. 207 (1813).
Rootstock a chain of hypogeal pseudo-bulbs about 1⁄2 inch in diameter, with thick vermiform roots; leafing stem 4-5 inches, sheathed; leaves 2 or 3, sessile, 8-12 inches long, oblong-lanceolate, acuminate, base narrowed, sheathing, bright green, shining, 3-5 ribbed beneath; peduncle from the base of a tuber, often distant from the leaves, 16-20 inches high, stout, with a few herbaceous tubular sheaths; raceme 3-5 in., sharply decurved in flower erect in fruit, rather closely 10-12 flowered; bracts lanceolate, mem- branous, shorter than the ovary; flowers subsessile, sepals and petals 1⁄2 inch long; linear-oblong, acute or obtuse, lip superior, subpanduriform, tip retuse, disk concave with a broad ridge ending in a yellow warted callus; fruits 14-11⁄2 inches fusiform, pendulous from a shortly decurved pedicel. (Modified slightly from (8) p. 178).
SYNONYMY:-Hooker in 1894 (6) p. 16, gives G. purpureum as a different species the differences recorded being:-scape longer than the leaves, lax flowered raceme and an acute lip. A few years later he writes.
"It is impossible from dried specimens to distinguish G. dilatatum, purpureum, and furcatum. They are possibly all forms of one species." J. D. H. 1898 (8) p. 178. In (7) p. 181-182. King and Pantling include G. dilatatum as synonymous with G. purpureum, and on plate VIII depict G. purpureum which drawings seem to agree in all essentials with our drawings of G. dilatatum illustrating this article.
The Hong Kong Naturalist.
December 1932.
LINCH
Orchidaceae of Hong Kong
171
Figure 1.
Geodorum dilatatum, R. Brown.
CANS
148