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FOC | Family List | FOC Vol. 25 | Orchidaceae

168. Thrixspermum Loureiro, Fl. Cochinch. 2: 516, 519. 1790.

白点兰属 bai dian lan shu

Authors: Xinqi Chen & Jeffrey J. Wood

Herbs, epiphytic, lithophytic, or rarely terrestrial, monopodial, medium-sized. Stems ascending, climbing, or pendulous, either short with several closely spaced leaves, or long with many, well-spaced leaves. Leaves flat, never terete or laterally compressed, sometimes fleshy, base sheathing, jointed. Inflorescence lateral, axillary, racemose, long or short, few to many flowered, a few flowers opening at a time, flowering of many lowland species initiated by a sudden afternoon rainstorm; floral bracts either distichous and persistent on a flattened rachis or facing all directions on terete rachis. Flowers usually ephemeral, often fully open for only half a day, small to medium-sized, very variable, from a few millimeters to several centimeters in diam. Sepals and petals subsimilar; lip adnate at base to end of column foot, immovable, saccate but not truly spurred, usually with a partly hairy or papillose front wall callus, 3-lobed; lateral lobes erect; mid-lobe rather thick and fleshy. Column short, stout, sometimes winged, with a long foot; pollinia waxy, 4, appearing as 2 unequal masses, subglobose, attached by a common short and broad stipe to a solitary viscidium. Capsule long, slender.

About 100 species: Sri Lanka and the Himalayan region east to the Pacific islands, with an apparent center of distribution in Sumatra; 14 species (two endemic) in China.

1 Floral bracts distichous on a ± flattened rachis   (2)
+ Floral bracts facing all directions (quaquaversal) on a terete rachis   (4)
2 (1) Floral bracts ca. 5 mm apart from each other; rachis slender, shorter than 5 cm.   12 T. japonicum
+ Floral bracts close, 1-3 mm apart from each other; rachis stout, longer than 5 cm   (3)
3 (2) Leaves ovate-lanceolate, base cordate, 2-2.5(-5) cm.   13 T. amplexicaule
+ Leaves oblong, base narrowed, 6-24 cm.   14 T. centipeda
4 (1) Plants pendulous or arcuate; stems 30-90 cm; inflorescence 1-2 cm   (5)
+ Plants ascending; stems 2-3(-7) cm; inflorescence 3-8 cm   (7)
5 (4) Leaves linear-lanceolate or lorate, abruptly narrowed some distance from apex, acute; stems often branching.   1 T. subulatum
+ Leaves oblong or elliptic, apex obtusely unequally bilobed or acute; stems simple   (6)
6 (5) Stems flaccid; leaves elliptic, only narrowed a slight distance from apex, acute, dorsally carinate, 5-7 × 2-2.7 cm.   2 T. pensile
+ Stems not flaccid, stout; leaves oblong, obtusely unequally bilobed, 6-12 × 1.9-2.2 cm.   3 T. tsii
7 (4) Flowers well spaced, opening simultaneously, lasting several days   (8)
+ Flowers close, opening successively, lasting less than a day   (9)
8 (7) Flowers white, often tinged with purplish or yellowish; lip with a basal callus; callus with a tuft of brownish yellowish hairs.   4 T. saruwatarii
+ Flowers creamy yellow; lip without a basal callus, base with a tuft of purple hairs.   5 T. laurisilvaticum
9 (7) Sac of lip cylindric, ca. 6 mm.   6 T. formosanum
+ Sac of lip saccate or pouch-shaped, less than 4 mm   (10)
10 (9) Lip nearly triangular or rhombic in outline; mid-lobe with 2 or 3 tufts of white hairs   (11)
+ Lip not triangular nor rhombic in outline; mid-lobe lacking hairs   (12)
11 (10) Flowers yellow; mid-lobe of lip truncate at apex; disk with 2 conic calli and 3 tufts of white hairs.   7 T. merguense
+ Flowers white; mid-lobe of lip slightly bilobed at apex; disk with a longitudinal hairy callus.   8 T. annamense
12 (10) Lip with dense minute papillae adaxially; lateral lobes with white clavate cilia along apical margin; mid-lobe small, entire.   9 T. trichoglottis
+ Lip (except fleshy ridges) glabrous adaxially; lateral lobes entire or denticulate at margins; mid-lobe irregularly dentate at margin   (13)
13 (12) Lateral lobes of lip entire; disk with a Y-shaped callus.   10 T. eximium
+ Lateral lobes of lip denticulate at apical margin; disk with 2 tubelike calli.   11 T. fantasticum

  • List of lower taxa


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