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1. Begonia Linnaeus, Sp. Pl. 2: 1056. 1753.
秋海棠属 qiu hai tang shu
Perennial succulent herbs, rarely subshrubs. Stem erect, frequently rhizomatous, or plants tuberous and either acaulescent or shortly stemmed, rarely lianoid or climbing with adventitious roots, or stoloniferous. Leaves simple, rarely palmately compound, alternate or all basal; blade often oblique and asymmetric, rarely symmetric, margin often irregularly serrate and divided, occasionally entire, venation usually palmate; petiole long, weak; stipules membranous, usually deciduous. Flowers unisexual, plants monoecious, rarely dioecious, (1 or)2-4 to several, rarely numerous, in dichotomous cymes, sometimes in panicle, with pedicels and bracts. Staminate flower: tepals 2 or 4 and decussate, usually outer ones larger, inner ones smaller; stamens usually numerous; filaments free or connate at base; anthers 2-celled, apical or lateral; connectives extended at apex, sometimes apiculate. Pistillate flower: tepals 2-5(-10); pistil composed of 2-5(-7) carpels; ovary inferior, 1-3(-7)-loculed; placentae axile or parietal; styles 2 or 3(or more), free or fused at base, forked once or more; stigma turgid, spirally twisted-tortuous or U-shaped, capitate or reniform, setose-papillose. Capsule dry, sometimes berrylike, unequally or subequally 3-winged, rarely wingless and 3- or 4-horned; seeds very numerous, pale brown, oblong, minute, testa reticulate.
More than 1400 species: widely distributed in the tropical and subtropical regions of the world, with ca. 150 species in Africa, more than 600 species in Central and South America, and more than 600 species in Asia; 173 species (141 endemic) in China.
Begonia species in China are mostly distributed S of the Chang Jiang, particularly concentrated in SE Yunnan and SW Guangxi, with only a few extending into N China. The authors learned of two additional, recently described species as this volume was going to press. Begonia guaniana H. Ma & H. Z. Li (Ann. Bot. Fenn. 43: 466. 2006) was described from NE Yunnan (Yanjin), where it grows on moist cliffs under bamboo forest at ca. 500 m. Its chromosome number is 2n = 24*. It resembles B. labordei, especially in its tuberous, stemless habit. Begonia coelocentroides Y. M. Shui & Z. D. Wei (Acta Phytotax. Sin. 45: 86. 2007) was described from W Yunnan (Yingjiang), where it grows on cliffs often in forests or near streams at ca. 1300 m, flowering in August and fruiting in October. It resembles B. oreodoxa in having parietal placentae at the upper part of the ovary, differing mainly in the female flowers with 5 tepals and the largest wing of the capsule being 20-22 mm and ligulate. The records of Begonia balansana Gagnepain from Guangxi and Yunnan in FRPS (52(1): 212. 1999) are possibly errors and require confirmation. The second author has seen no specimens from China that would substantiate these records. This species is believed to be endemic to N Vietnam. See also Tebbitt (Edinburgh J. Bot. 60: 1-9. 2003). It can be difficult to key out the sections of Begonia, because sectional distinctions rely heavily on the placentation structure, which is either unavailable on specimens or difficult to analyse (many Begonia specimens are poorly prepared). Information on sections to which Begonia species belong may be desirable to specialists, although it should be noted that there are disagreements about the placement of some species. Please refer to Y. M. Shui, C.-I Peng & C. Y. Wu, Synopsis of the Chinese species of Begonia (Begoniaceae), with a reappraisal of the sectional delimitation (Bot. Bull. Acad. Sin. 43: 313-327. 2002). In China, all species are perennial herbs (rarely subshrubs). All species with basal tubers are described as deciduous, although living material is not available for all tuberous species. The aerial parts of the plants wilt in winter or in the dry season. Most species are monoecious with cymose, dichasial inflorescences. The inflorescences are usually protandrous (staminate flowers open before pistillate flowers) and gynaeandrous (staminate flowers basal and pistillate flowers distal).
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Key 8
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| 1 |
Styles 2; ovary 2-loculed. |
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109 B. oreodoxa |
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Styles 3; ovary 3-loculed |
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(2) |
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| 2 (1) |
Middle cross-section of ovary with septal placentation or connecting tissue at center |
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(3) |
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Middle cross-section of ovary with parietal placentation |
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(6) |
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| 3 (2) |
Staminate and pistillate tepals 2; leaf adaxially sparsely appressed rusty fibrillose. |
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74 B. jingxiensis |
| + |
Staminate tepals 4, pistillate tepals 3 |
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(4) |
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| 4 (3) |
Leaf adaxially glabrous. |
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173 B. zhengyiana |
| + |
Leaf adaxially hairy |
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(5) |
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| 5 (4) |
Leaf adaxially long hirsute, tertiary veins obscure. |
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152 B. suboblata |
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Leaf adaxially sparsely pilose-setose, tertiary veins conspicuous, percurrent. |
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142 B. semiparietalis |
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| 6 (2) |
Leaf without a distinct apex, adaxially glabrous. |
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173 B. zhengyiana |
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Leaf blade with a distinct apex, adaxially ± pubescent |
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(7) |
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| 7 (6) |
Inflorescence a thyrsoid cyme; leaves 23-50 × 16-40 cm. |
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85 B. liuyanii |
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Inflorescence a dichasial cyme; leaves smaller |
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(8) |
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| 8 (7) |
Leaf surface strongly bullate or pustulate |
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(9) |
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Leaf surface flat or rugose |
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(10) |
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| 9 (8) |
Leaf blade with dark brown to black broad palmate bands, apex shortly acuminate. |
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97 B. masoniana |
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Leaf blade without dark palmate bands, apex rounded. |
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50 B. fimbribracteata |
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| 10 (8) |
Leaf blade sparsely hairy or subglabrous |
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(11) |
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Leaf blade densely to moderately hairy |
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(19) |
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| 11 (10) |
Leaf blade ovate to broadly lanceolate. |
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110 B. ornithophylla |
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Leaf blade broadly ovate to suborbicular |
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(12) |
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| 12 (11) |
Leaf blade often very shallowly angularly lobed, often with pale green to white spots at junction between veins and brownish spots in intercostal areas; tertiary veins randomly reticulate, divergence angle 40°-60°. |
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93 B. luzhaiensis |
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Leaf blade unlobed, spot not as above; tertiary veins ± percurrent, divergence angle 60°-120° |
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(13) |
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| 13 (12) |
Tertiary veins oppositely percurrent, divergence angle 90°-120° |
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(14) |
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Tertiary veins obliquely alternately percurrent, divergence angle 60°-80° |
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(16) |
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| 14 (13) |
Leaf blade 3.5-15 × 3-13 cm, adaxially with whitish spots along major veins. |
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142 B. semiparietalis |
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Leaf blade 12-32 × 11-27 cm, adaxially not as above |
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(15) |
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| 15 (14) |
Leaf blade apically acute to shortly acuminate, adaxially with a broad whitish ring. |
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80 B. lanternaria |
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Leaf blade apically obtuse to rounded, adaxially without spot or with white spot between major veins. |
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31 B. crystallina |
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| 16 (13) |
Leaf petiole appressed-pilose, blade subleathery; ovary obovoid. |
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125 B. pseudoleprosa |
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Leaf petiole pilose or hirsute-villous, blade herbaceous; ovary ovoid to ellipsoid |
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(17) |
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| 17 (16) |
Leaf blade 5-9 × 6-8 cm, apex obtuse to rounded. |
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10 B. austroguangxiensis |
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Leaf blade larger, longer than 10 cm, apex acuminate or shortly so |
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(18) |
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| 18 (17) |
Leaf blade green throughout; stipules apically obtuse to emarginate. |
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123 B. pseudodaxinensis |
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Leaf blade adaxially with a broad whitish ring; stipules apically acute. |
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36 B. daxinensis |
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| 19 (10) |
Rhizomes slender, long creeping or vinelike, internodes elongate, usually longer than 1 cm |
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(20) |
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Rhizomes stout, internodes usually shorter than 1 cm |
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(24) |
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| 20 (19) |
Capsule distinctly curved. |
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33 B. curvicarpa |
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Capsule not distinctly curved |
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(21) |
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| 21 (20) |
Stipules basally obliquely auriculate. |
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9 B. auritistipula |
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Stipules basally not auriculate |
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(22) |
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| 22 (21) |
Ovary and capsule beaked at summit. |
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134 B. rhynchocarpa |
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Ovary and capsule not beaked at summit |
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(23) |
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| 23 (22) |
Leaf blade moderately setulose. |
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37 B. debaoensis |
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Leaf blade densely pilose. |
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122 B. porteri |
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| 24 (19) |
Leaf tertiary veins randomly reticulate, never percurrent, thin, divergence angle 40°-60° |
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(25) |
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Leaf tertiary veins ± percurrent, abaxially prominent, divergence angle 60°-100° |
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(27) |
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| 25 (24) |
Leaf blade shallowly angularly lobed, adaxially sparsely tomentose. |
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93 B. luzhaiensis |
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Leaf blade unlobed, adaxially tomentose |
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(26) |
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| 26 (25) |
Leaf blade ovate, 10-25 × 5-18 cm, adaxially with a broad white band on midvein. |
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92 B. luochengensis |
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Leaf blade broadly ovate to suborbicular, 3-9 × 2-8 cm, adaxially without a broad white band. |
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122 B. porteri |
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| 27 (24) |
Leaf blade adaxially villous-hirsute, hairs reddish, 3-5 mm; capsule 1.5-2.1 cm. |
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59 B. guangxiensis |
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Leaf blade with other trichome types, hairs shorter than 2.5 mm; capsule to 1.2 cm |
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(28) |
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| 28 (27) |
Androecium actinomorphic |
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(29) |
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Androecium zygomorphic |
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(31) |
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| 29 (28) |
Peduncle glandular hispid; flowers usually greenish or yellowish green. |
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49 B. filiformis |
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Peduncle glabrous or pilose |
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(30) |
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| 30 (29) |
Leaf blade slightly rugose or nearly flat, sparsely setulose; flowers reddish to white. |
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13 B. biflora |
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Leaf blade distinctly rugose, densely pilose; flowers greenish yellow with reddish base. |
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90 B. longistyla |
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| 31 (28) |
Peduncle densely hirsute-villous |
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(32) |
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Peduncle pilose or glabrous |
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(33) |
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| 32 (31) |
Leaf blade surface flat or slightly rugose, lacking spots, hairs sparser. |
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26 B. cirrosa |
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Leaf blade surface rugose, with a broad white or pale ring, hairs denser. |
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118 B. picturata |
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| 33 (31) |
Ovary glandular pilose, abaxial wing obliquely triangular. |
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107 B. obliquifolia |
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Ovary not glandular pilose, abaxial wing usually lunate or oblong (sometimes obliquely triangular in B. retinervia) |
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(34) |
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| 34 (33) |
Leaf blade slightly rugose or nearly flat |
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(35) |
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Leaf blade distinctly rugose |
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(36) |
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| 35 (34) |
Fruit or ovary sparsely hairy, wings unequal. |
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71 B. huangii |
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Fruit or ovary glabrous, wings equal or subequal. |
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120 B. platycarpa |
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| 36 (34) |
Leaf blade with a white ring. |
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103 B. morsei |
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Leaf blade often with a white band along major veins |
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(37) |
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| 37 (36) |
Capsule crisped-villous, broadly ovoid, apex with short beak. |
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132 B. retinervia |
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Capsule glabrous or near so, ellipsoid, apex without short beak. |
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106 B. ningmingensis |
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List of Keys
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List of lower taxa
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