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