1	Calyx spathaceous, splitting along one side or into 2 unequal lobes; trees or shrubs without tendrils; flowers with 5 or 10 fertile stamens (or with female flowers lacking anthers) (B. purpurea with 3 fertile stamens)		(2)
+	Calyx with 4 or 5 ± equal lobes; lianas usually with tendrils (B. bohniana an erect shrub 1-2 m high); flowers with 2 or 3 fertile stamens		(10)
2 (1)	Petals 0.7-1.2 cm		(3)
+	Petals 3-8 cm		(5)
3 (2)	Flowers bisexual with 10 unequal fertile stamens and well-developed ovary; petals yellowish; legume 12-20-seeded.		8 B. racemosa
+	Flowers unisexual, lacking either functional ovary or fertile anthers; petals white or greenish white; legume 2-10-seeded		(4)
4 (3)	Inflorescence leaf-opposed, 10-15-flowered; stamens ca. 10 mm; legume 6-10-seeded.		6 B. viridescens
+	Inflorescence terminal, to 50-flowered, sometimes much condensed; stamens 5-6 mm; legume 2-7-seeded.		7 B. brachycarpa
5 (2)	Fertile stamens 10; petals white; leaf blade ovate-cordate to cordate		(6)
+	Fertile stamens 3 or 5; petals pink, purple, or white with pink spots, occasionally all white; leaf blade orbicular, suborbicular, or broadly ovate		(8)
6 (5)	Leaf blade 3-7 × 4-8 cm, papery, abaxially tomentose.		9 B. tomentosa
+	Leaf blade 6-11(-16) × 8-12.5 cm, subleathery, abaxially pubescent		(7)
7 (6)	Young shoots glabrous; leaf bifid to 1/3-2/5; legume sharply ridged near suture.		1 B. acuminata
+	Young shoots brownish pubescent or hirsute; leaf bifid to 1/4; legume not ridged near suture.		3 B. hirsuta
8 (5)	Fertile stamens 3, staminodes 5 or 6; leaf bifid to 1/3-1/2, lobes slightly acute or rarely rounded at apex.		4 B. purpurea
+	Fertile stamens 5, staminodes 1-5, sometimes absent; leaf bilobed to 1/4-1/3, lobes rounded or narrowly rounded		(9)
9 (8)	Petals purplish, 5-8 cm; sterile hybrid not forming fruit.		2 B. ×blakeana
+	Petals white, often with pink or purple spots, 4-5 cm; legume linear, 15-25 × 1.5-2 cm.		5 B. variegata
10 (1)	Leaves 2-foliolate, primary veins 3-5 per lobe		(11)
+	Leaves entire or bifid for up to 1/2 length		(13)
11 (10)	Shoots hairy; leaf lobes acuminate; receptacle ca. 5 mm.		37 B. carcinophylla
+	Shoots glabrous; leaf lobes obtuse; receptacle 7-12 mm		(12)
12 (11)	Tendrils solitary; receptacle 10-12 mm; petals white, broadly obovate, ca. 9 mm.		42 B. didyma
+	Tendrils paired; receptacle 7-8 mm; petals pinkish with dark red stripes, spatulate, ca. 17 mm.		24 B. yunnanensis
13 (10)	Leaves entire to shallowly bifid for up to 1/6 length, primary veins 3-9		(14)
+	Leaves bifid for more than 1/5 length, primary veins 7-13		(25)
14 (13)	Petals orange or reddish, 25-30 mm.		23 B. coccinea
+	Petals white or greenish white (color not recorded for B. cercidifolia or B. wuzhengyii), 2.5-10 mm		(15)
15 (14)	Leaf blade abaxially glabrous or nearly so		(16)
+	Leaf blade abaxially pubescent		(20)
16 (15)	Leaf blade 1.5-4 cm; inflorescence a simple raceme, 5-9 cm.		20 B. venustula
+	Leaf blade 4.6-10 cm; inflorescence a panicle, or if unbranched then more than 10 cm		(17)
17 (16)	Leaf blade with primary veins 3-5, base attenuate or rounded; petals 4-10 mm; tendrils rare or apparently absent		(18)
+	Leaf blade with primary veins usually 7-9, base shallowly cordate to truncate; petals 2.5-3 mm; tendrils usually present		(19)
18 (17)	Petals 4-5 mm; leaf base rounded.		27 B. paucinervata
+	Petals 7-10 mm; leaf base attenuate.		31 B. wuzhengyii
19 (17)	Fertile stamens 3; petiole 2-4 cm; leaf blade 4-8 cm wide, papery; pedicel 3-4 mm.		13 B. scandens
+	Fertile stamens 2; petiole 4.5-5 cm; leaf blade 9-11 cm wide, leathery; pedicel ca. 18 mm.		15 B. cercidifolia
20 (15)	Inflorescence 7-25 cm, pedicels 3.5-15 mm; petals 3.5-6 mm; staminodes 2		(21)
+	Inflorescence 3.5-8 cm, pedicels 15-22 mm; petals 6-10 mm; staminodes 7: 2 longer and free, others joined at base (not recorded for B. apertilobata)		(23)
21 (20)	Pedicel 3.5-4 mm.		19 B. lingyuenensis
+	Pedicel 10-15 mm		(22)
22 (21)	Leaf blade ovate or cordate; petals spatulate.		17 B. championii
+	Leaf blade suborbicular; petals obovate or oblong.		10 B. longistipes
23 (20)	Flower bud ellipsoid with protruding apex; receptacle broadly funnelform; petals spatulate.		16 B. apertilobata
+	Flower bud ovoid; receptacle cylindric or elongate; petals subrhombic, broadly obovate, or elliptic		(24)
24 (23)	Leaf blade 5-8 × 4-6.5 cm; receptacle 8-9 mm; petals unequal, 3 rhombic, 2 elliptic, claw 3-4 mm.		44 B. quinnanensis
+	Leaf blade 3-4 × 2-3 cm; receptacle ca. 15 mm; petals subrhombic, broadly obovate, or elliptic, claw 6-8 mm 46.		B. ovatifolia
25 (13)	Erect shrubs, tendrils absent; petals pink.		25 B. bohniana
+	Lianas, tendrils present; petals white or light yellowish, rarely with pink veins or reddish base, or red or golden yellow (sometimes pale pink in B. hainanensis)		(26)
26 (25)	Ovary glabrous		(27)
+	Ovary hairy, at least on sutures		(33)
27 (26)	Leaf blade bifid for more than 1/2 length		(28)
+	Leaf blade bifid for 1/5-1/2 length		(30)
28 (27)	Inflorescence ca. 5 cm; bracts and bracteoles ca. 3 mm; petals white with pink veins; legume 10-25 cm.		41 B. corymbosa
+	Inflorescence 10-30 cm; bracts and bracteoles 5-9 mm, brushlike in young inflorescences; petals yellow or whitish yellow; legume 5-8 cm		(29)
29 (28)	Flower buds ovoid; staminodes 2; floral disk annular.		11 B. comosa
+	Flower buds conical; staminodes 4; floral disk U-shaped.		12 B. esquirolii
30 (27)	Fertile stamen filament 25-30 mm; receptacle 3-5 mm; leaf blade 8-18 cm		(31)
+	Fertile stamen filament 8-12 mm; receptacle 7-15(-30) mm; leaf blade 4-6(-9) cm		(32)
31 (30)	Pedicel 1-1.5 cm; calyx lobes not reflexed, one free, others in 2 adnate parts, ca. 6 mm; staminodes 2.		28 B. hainanensis
+	Pedicel 2-2.8 cm; calyx lobes reflexed at anthesis, ovate, ca. 10 mm; staminodes 5-7.		21 B. chalcophylla
32 (30)	Shoots glabrous; calyx lobes 5; legume 12-15 cm.		45 B. damiaoshanensis
+	Shoots reddish pubescent when young; calyx lobes 2 or 3; legume 18-25 cm.		40 B. glauca
33 (26)	Leaf blade abaxially glabrous		(34)
+	Leaf blade abaxially hairy at least on veins		(36)
34 (33)	Stems glabrous; leaf blade with yellowish margin.		29 B. japonica
+	Stems hairy at least when young; leaf blade uniformly green		(35)
35 (34)	Leaf blade 10-15 cm wide, bifid for up to 1/5 length; pedicel ca. 1.5 cm.		30 B. wallichii
+	Leaf blade 5-10 cm wide, bifid for at least 1/2 length; pedicel 4-5 cm.		36 B. erythropoda
36 (33)	Leaf blade 9-18(-20) cm wide, abaxially tomentose when young		(37)
+	Leaf blade 3.5-9(-12) cm wide, abaxially pubescent when young		(40)
37 (36)	Leaf blade abaxially thickly golden tomentose, primary veins 15-17; inflorescence conical; pedicel 0.9-1 cm.		33 B. hypochrysa
+	Leaf blade abaxially rusty or yellow-brown tomentose, primary veins 9-13; inflorescence ± flat-topped to rounded; pedicel 2-5 cm		(38)
38 (37)	Petiole 8-11 cm; bracts persistent.		39 B. ornata
+	Petiole 1.2-7 cm; bracts caducous		(39)
39 (38)	Leaf blade 12-18(-23) cm.		35 B. aurea
+	Leaf blade 9-12.5 cm.		34 B. rubrovillosa
40 (36)	Petals red or golden yellow.		26 B. khasiana
+	Petals white, sometimes reddish at base or tinged yellow or green		(41)
41 (40)	Petals 4-6 mm		(42)
+	Petals 15-30 mm		(44)
42 (41)	Leaf blade bifid to 1/6-1/5 of length; bracts 6-9 mm; lower pedicels to 20 mm.		43 B. touranensis
+	Leaf blade bifid to 1/3-1/2 of length; bracts 3-4 mm; lower pedicels 3-5 mm		(43)
43 (42)	Flower bud ca. 2 mm; leaf blade and legume valves leathery.		14 B. delavayi
+	Flower bud ca. 5 mm; leaf blade papery; legume valves woody.		18 B. hypoglauca
44 (41)	Calyx lobes 2 or 3; petals to 15 mm, apex acute.		38 B. calciphila
+	Calyx lobes 5; petals 20-30 mm, apex emarginate		(45)
45 (44)	Inflorescence conical; pedicel 0.7-3 cm; calyx lobes not reflexed.		32 B. pyrrhoclada
+	Inflorescence ± flat-topped; pedicel 4-5 cm; calyx lobes reflexed		(46)
46 (45)	Calyx lobes ca. 12 mm; filaments 15-17 mm, lower part pubescent.		36 B. erythropoda
+	Calyx lobes 25-30 mm; filaments ca. 35 mm, glabrous.		22 B. nervosa