Determination Key to the Genera (updated from Schaefer & Renner 2011)

1. Tendrils absent 2

– Tendrils present 14

2. Trees or (sub)shrubs or erect herbs, not climbing or trailing 3

– Herbaceous trailers or creepers 11

3. Trees to 6 m tall with large trunks (to 1 m across). Socotra Dendrosicyos

– Shrubs or subshrubs or erect herbs 4

4. Shrubs or subshrubs 5

– Erect or prostrate herbs 7

5. Plants not spiny. Africa, Madagascar, and Asia Corallocarpus

– Plants spiny 6

6. Tendrils transformed into c. 1 cm long, straight spines; leaves reduced to small scale like, ovate, c. 2 mm long bracts; thecae flexuous. Southern Africa Acanthosicyos

– On older stems, the bases of the tendrils thickened and transformed into a pair of straight or curved, rather blunt, 0.4–3 cm long spines; leaves well-developed, petiolate, 2–7 by 2–5 cm, broadly ovate; thecae curved. East and Northeast Africa Momordica

7. Fruit a small subglobose berry, to 2 cm long 8

– Fruit a large gourd-like pepo, >2 cm long, ripening green or yellow 9

8. Receptacle-tube cylindrical, 10–18 mm long with conical nectary; leaves entire or 3-lobed. South and East Africa Trochomeria

– Receptacle-tube shallowly saucer-shaped, 0.5–1 mm long; leaves deeply palmately dissected. East Africa Cucumis

9. Ripe fruit expelling seeds explosively. Mediterranean region and North Africa Ecballium

– Fruit indehiscent 10

10. Fruit <10 cm across; anthers distinct. Africa Cucumis

– Fruit >10 cm across; anthers connate into a central head. America, introduced in Africa, Europe, Asia, Australia Cucurbita

11. Plant spiny. Southern Africa Citrullus

– Plant not spiny 12

12. Plant with long underground branches and subterranean fruits. Southern Africa Kedrostis

– Plant creeping and fruiting above ground 13

13. Thecae flexuous, glabrous. Southern Africa Citrullus

– Thecae straight, fringed with hairs. Brazil Melothria

14. Tendrils in groups of 5–8 per node, simple; fruit geocarpic, maturing below ground. Southern Africa Cucumis

– Tendrils solitary (1 or rarely 2 per node), simple or 2–8-fid with a basal, unbranched part; fruit usually maturing above ground (but see Echinopepon) 15

15. Tendrils simple, not 2-fid or multi-fid with basal, unbranched part 16

– Tendrils 2–8-fid (often only at apex, which might be lost in herbarium material) 103

16. Thecae fringed with hairs 17

– Thecae glabrous (or hairs minute) 20

17. Stamens 3; anthers all 2-thecous. Africa, Asia, Australia, and Pacific Islands Zehneria

– Stamens 3; two anthers 2-thecous, one 1-thecous 18

18. Testa covered by long appressed hairs. South and Central America (naturalized in Asia) Melothria

– Testa glabrous 19

19. Fruit small, gourd-like, to 2.5 cm long, ornamented with long, soft bristles. Madagascar, Indonesia, Northeastern Australia Muellerargia

– Fruit a globose to ellipsoid, up to 20 cm long, smooth pepo. Tropical Africa and South/Central America Melothria

20. Ovules few, pendent; pollen small to medium-sized, striate 21

– Ovules many, horizontal; pollen mostly medium-sized to large, reticulate, perforate, gemmate or echinate/baculate, very rarely striate-reticulate (Dactyliandra, Papuasicyos) 23

21. Fruit indehiscent, globose. South America Sicydium

– Fruit dehiscent. Asia 22

22. Fruit dehiscing into 3 valves; seeds winged Zanonia

– Fruit operculate; seeds winged or unwinged Actinostemma

23. Petals fringed 24

– Petals not fringed 26

24. Stamens 5; anthers all 1-thecous; thecae triplicate. Madagascar Ampelosicyos

– Stamens 3; two anthers 2-thecous, one 1-thecous 25

25. Anthers connate into a central head; filaments distinct. Hispaniola Linnaeosicyos

– Anthers distinct. Asia Trichosanthes

26. Pollen echinate or perforate 27

– Pollen reticulate or striate-reticulate 35

27. Filaments connate into a central column 28

– Filaments distinct, sometimes very short or absent 32

28. Thecae connate into a horizontal, ring-like structure. South and Central America Cyclanthera

– Thecae distinct or connate into a central head-like structure 29

29. Fruits fleshy, unarmed, indehiscent, 1-seeded. Central America Sicyos

– Fruit ± dry, seeds few to many 30

30. Fruit globose, smooth, 5–7 cm in diam., indehiscent. Hispaniola Penelopeia

– Fruit dehiscent, ± setose or prickly. America 31

31. Fruit operculate; seeds relatively small, ± compressed Echinopepon

– Fruit not operculate; seeds large, ± globose Marah

32. Fruit a large, fleshy, indehiscent pepo 33

– Fruit a small dry or fleshy berry 34

33. Petals yellow. America, introduced in Africa, Europe, Asia, Australia Cucurbita

– Petals greenish white. Central America Cionosicyos

34. Fruit a fleshy berry, ripening red. Argentina and Uruguay Abobra

– Fruit a dry berry with a firm, thin wall, ripening green, red, brown or black; seeds in loose cellular pulp. America Cayaponia

35. Pollen striate-reticulate 36

– Pollen reticulate or gemmate 37

36. Stigma 3-lobed. Africa and Asia Dactyliandra

– Stigma-lobes feather-like divided. New Guinea Papuasicyos

37. Stamens 5 38

– Stamens 2–3 44

38. Thecae triplicate/sinuate 39

– Thecae straight or ± curved 40

39. Sepals > petals. Indonesia Zehneria

– Sepals < petals. Africa and Socotra Eureiandra

40. Plant densely black- or reddish-glandular hairy. Tropical Africa Siraitia

– Plant glabrous or hairy but not black- or reddish-glandular 41

41. Seeds pear-shaped to subglobose. Africa, Madagascar, Asia 42

– Seeds ovate-oblong, ± compressed. Asia 43

42. Fruit operculate, the basal part of the fruit green, expanded into a cup, the upper part red Corallocarpus

– Fruit indehiscent or opening by valves, ripening entirely orange to red Kedrostis

43. Petals small, to 5 mm long, cream-colored or white Baijiania

– Petals >5 mm long, yellow Thladiantha

44. Stamens 2 45

– Stamens 3 50

45. Adult plants usually leafless with succulent stems. Madagascar Seyrigia

– Adult plants with well-developed leaves; stems not succulent 46

46. Sepals showy, orange to red, sepals > petals. Tropical America Gurania

– Sepals green or dark-colored, sepals < petals 47

47. Flowers small; petals inconspicuous, c. 3 mm long, yellowish-green. Tropical America Helmontia

– Flowers medium-sized; petals >5 mm long, yellow, orange or white 48

48. Male flowers often subtended by a ± orbicular bract, often 1–3 of the petals with an incurved basal scale. Africa and Asia, introduced in Australia and America Momordica

– Male flowers not subtended by bracts; petal scales absent 49

49. Pollen often in tetrads; woody or less often herbaceous climber; petals orange, red or pink. Tropical and subtropical America Psiguria

– Pollen in monads; herbaceous climber or trailer; petals greenish-white to yellow. Southern US to Argentina Apodanthera

50. Pollen in tetrads. Indonesia Borneosicyos

– Pollen in monads 51

51. Male flowers often subtended by a ± orbicular bract, often 1–3 of the petals with an incurved basal scale. Africa and Asia, introduced in Australia and America Momordica

– Male flowers not subtended by an orbicular bract, petal scales absent 52

52. Petiole base with suborbicular ciliate bract 53

– Petiole base without ciliate bract 54

53. Thecae linear, straight; petals ± 1 mm long. Africa, Madagascar, and Asia Blastania

– Thecae triplicate; petals larger. Africa and Madagascar Trochomeria

54. Thecae straight or slightly curved (sometimes apically hooked) 55

– Thecae strongly curved, duplicate, triplicate or flexuous 79

55. Petals 2-furcate to deeply 2-fid. Central and South America 56

– Petals entire 57

56. Filaments very short, distinct Ceratosanthes

– Filaments longer, connate into a central column Ibervillea

57. Fruit a large, hard-shelled pepo, to 20 cm long; thecae fringed with hairs. Tropical Africa and America Melothria

– Fruit smaller, a fleshy berry or gourd; if large (Cucumis melo), then thecae not hairy 58

58. Fruit ornamented 59

– Fruit ± smooth 60

59. Fruit with long, soft bristles. Madagascar, Northern Australia, and Indonesia Muellerargia

– Fruit with dense to scattered fleshy spines, pustules or tubercles that end in a hyaline bristle. Africa, Asia, naturalized in America, Australia, and the Pacific Islands Cucumis

60. Stamens inserted near the base or halfway up the receptacle-tube 61

– Stamens inserted in the upper half or near the mouth of the receptacle-tube 62

61. Anthers all 2-thecous; leaves petiolate, triangular to ± ovate, entire to 3-lobed. Africa, Asia, Australia, and Pacific Islands Zehneria

– Two anthers 2-thecous, one 1-thecous; leaves shortly petiolate to sessile, base cordate or hastate. Asia Solena

62. Filaments connate into a central column. Mexico and Southern US 64

– Filaments distinct or very short to absent 63

63. Fruit a fusiform or ellipsoid berry, shortly rostrate, 6–15 cm long and 3–6 cm in diam. Ibervillea

– Fruit a globose berry, c. 1 cm in diam., glabrous, with remains of flower Tumamoca

64. Stigma 3-lobed, long-hairy. Southeast Asia Indomelothria

– Stigmas 1–5, entire or lobed, if 3-lobed, then glabrous, papillose or short-hairy

65. Stigmas 2. Central and South America 66

– Stigmas 3–5 67

66. Fruit fleshy, indehiscent, ovoid to ellipsoid, ± rostrate, 1–7 cm long, ripening green or red to brown often with white stripes or spots Apodanthera

– Fruit an ovoid-conical berry, c. 2 cm long and 1.5 cm in diam., sessile in the leaf axils, rostrate Wilbrandia

67. Stigmata 4–5 68

– Stigmata 3 69

68. Testa smooth, chocolate-brown, often with distinct, ivory-colored margin. Southern US to Argentina Apodanthera

– Testa smooth, margin ± distinct, not winged. South America Cucurbitella

69. Two anthers 2-thecous, one 1-thecous 70

– All anthers 2-thecous 73

70. Testa covered by long appressed hairs. America, introduced in Asia Melothria

– Testa glabrous or rarely puberulent 71

71. Testa light-colored, ± yellowish. Africa, Asia, Australia, introduced in America Cucumis

– Testa brown 72

72. Testa finely sculptured, no distinct margin. Madagascar Trochomeriopsis

– Testa smooth, often with distinct, ivory-colored margin. Southern US to Argentina Apodanthera

73. Anthers 2 74

– Anthers 3 75

74. Testa chocolate-brown. Southern US to Argentina Apodanthera

– Testa pale brown or yellowish. Africa, Asia, Australia Zehneria

75. Seeds tumid to globose 76

– Seeds compressed 77

76. Disk in male flowers urceolate, ± connate with base of tube. New Guinea Papuasicyos

– Disk in male flowers ± globose, distinct. Africa, Asia, Australia Zehneria

77. Testa covered by long appressed hairs. America, introduced in Asia Melothria

– Testa glabrous 78

78. Stigmas hairy. Southeast Asia Scopellaria

– Stigmas glabrous or papillose but not hairy. Africa, Asia, Australia Zehneria

79. Thecae strongly curved or duplicate 79

– Thecae triplicate or flexuous 80

80. Filaments inserted near the base or in the lower half of the receptacle-tube 81

– Filaments inserted halfway up or in the upper half of the tube 82

81. Leaves petiolate, triangular to ± ovate, entire to 3-lobed; disk in male flowers globose, entire or 3-parted. Africa, Asia, Australia, and Pacific Islands Zehneria

– Leaves shortly petiolate to sessile, base cordate or hastate; disk in male flowers 3–4-lobed, conspicuous, carnose. Asia Solena

82. Receptacle-tube elongate, tubular to cylindrical, often dilated at the apex. Asia, Australia, introduced in Africa and the Neotropics Trichosanthes

– Receptacle-tube broadly campanulate or ± cylindrical but not elongated 83

83. Fruit laterally compressed, shortly rostrate. Argentina Halosicyos

– Fruit ellipsoid to oblong or subglobose, not laterally compressed, sometimes rostrate 84

84. Seeds pear-shaped, slightly compressed, reddish brown, with distinct pale brown margin. Central America Doyerea

– Seeds compressed, pale or dark-colored 85

85. Testa verrucous. Brazil Melothrianthus

– Testa smooth or finely scrobiculate 86

86. Testa finely scrobiculate. New Guinea Papuasicyos

– Testa smooth 87

87. Testa brown. Southern US to Argentina Apodanthera

– Testa pale yellowish or cream-colored 88

88. Staminodes forming a ring; seeds with distinct margin. Madagascar Blastania

– Staminodes distinct; seeds without distinct margin or rarely margin thickened. Australia Austrobryonia

89. Filaments inserted halfway up or in the upper half of the tube 89

– Filaments/stamens inserted near the base or in the lower half of the receptacle-tube 92

90. Seeds with broad, flattened margin; leaves pedately 3–7-lobed, drying black. Tropical West Africa Ruthalicia

– Seeds without distinct margin or margin narrow; leaves unlobed or palmately 3–5-lobed, usually drying green 91

91. Seeds tumid, subglobose, or asymmetrically ovoid. Africa and Socotra Eureiandra

– Seeds ovate or elliptic, small to medium-sized, globose or lenticular compressed. Africa, Asia, Australia, introduced in America Cucumis

92. Fruit densely brown-setose. Tropical Africa and Madagascar Raphidiocystis

– Fruit ± glabrous or sparsely setose or hairy or with prominent spines but not brown-setose 93

93. Fruit hairy 94

– Fruit ± glabrous 96

94. Testa blackish, smooth, not winged, no distinct margin. Africa and Madagascar Peponium

– Testa brown or grayish-brown, without distinct margin or with dentate or narrow, corky margin 95

95. Testa brown; leaves petiolate, palmately 3–5-lobed, the lobes lobulate-dentate. Madagascar Lemurosicyos

– Testa grayish-brown; leaves shortly petiolate to sessile, the blade ovate or elliptic, margin entire, base cordate or hastate. Asia Solena

96. Leaves very shortly petiolate to sessile, ± amplexicaul 97

– Leaves with distinct petioles 100

97. Seeds slightly compressed to ± globose 98

– Seeds strongly compressed 99

98. Testa grayish-brown, sometimes with narrow, corky margin. Asia Solena

– Testa whitish, without distinct margin. Africa and Madagascar Trochomeria

99. Testa black, verrucous. Africa Cephalopentandra

– Testa pale, smooth to fibrillose. Africa, Asia, introduced in Australia and America Coccinia

100. Seeds subglobose, ovoid or ellipsoid, tumid; testa smooth, hard, whitish. Africa and Madagascar Trochomeria

– Seeds compressed 101

101. Testa bright brown, finely grooved, with broad, grooved, crenulate-tuberculate margin. Cambodia Khmeriosicyos

– Testa without distinct margin or margin not grooved, crenulate-tuberculate 102

102. Receptacle-tube elongated, ± cylindrical. Africa and Madagascar Peponium

– Receptacle-tube campanulate or turbinate 103

103. Flowers small, in axillary, racemose panicles or sub-umbellate fascicles. Europe, Northern Africa, Canaries, Central Asia Bryonia

– Flowers medium-sized to large, if small then solitary (rarely in few-flowered fascicles). Africa and Asia, introduced in Australia and America 104

104. Thecae triplicate; style filiform; fruit small and globose or cylindrical and to 30 cm long, baccate, usually glabrous Coccinia

– Thecae flexuous; style short, columnar; fruit large, globose or oblong, glabrous or covered with prominent spines Citrullus

105. Tendrils 2-fid 106

– Tendrils 3–8-fid 173

106. Basal part of the tendrils sensitive and thus tendrils coiling above and below the bifurcation 107

– Basal part of the tendrils insensitive, not coiling 125

107. Sepals and petals 4; leaves entire or 3-lobed, orbicular or flat, succulent or non-succulent, perennial or deciduous. Madagascar Xerosicyos

– Sepals and petals 5, or sepals 3–4 and petals 5 108

108. Sepals 3–4 and petals 5 109

– Sepals and petals 5 111

109. Stamens 3, two anthers 2-thecous, one 1-thecous; thecae vertical; ovules many per locule; seeds with a butterfly-shaped wing, expanded laterally and divaricate. South East Asia to New Guinea Alsomitra

– Stamens 5, distinct; thecae horizontal; ovules 2 per locule 110

110. Leaves entire; seeds with a chalazal wing. Indomalesia Zanonia

– Leaves compound, palmate or pedate; seeds in the median position of an encircling wing expanded along the chalaza-micropyle axis. South America Siolmatra

111. Filaments connate into a central column 112

– Filaments ± distinct 115

112. Thecae 2–3, horizontal; fruit a samara, indehiscent 113

– Thecae 5, vertical; fruit a dry achene, indehiscent or a subglobose capsule, dehiscent 114

113. Thecae 2, semicircular, forming together a split ring. Africa and Madagascar Cyclantheropsis

– Thecae 3, straight, forming the sides of an equilateral triangle. South America Pteropepon

114. Leaves cordate; ovule 1 per ovary; fruit dry, globose, indehiscent; seed subspherical. Mexico Sicydium

– Leaves compound, pedate, 3–7-foliolate; stylodia 3; ovules more than 1 (usually 2–4) per ovary; fruit a subglobose capsule (3-valvate at the apex), dehiscent; seeds not compressed, unwinged or winged. Asia and Indomalesia Gynostemma

115. Stamens 1, anther 2-thecous. South America Pteropepon

– Stamens 2–5, all anthers 1-thecous, distinct or two anthers 2-thecous, one 1-thecous (sometimes the 1-thecous or one of the 2-thecous anthers reduced or aborted) 116

116. Stamens 3, two anthers 2-thecous, one 1-thecous; ovary 1-locular; ovule 1 per ovary; fruits indehiscent, baccate; seed subspherical 117

– Stamens 4 and 1 staminode or stamens 5 119

117. Fruit a cylindrical-clavate capsule, c. 20 cm long, opening with 3 valves; seeds with broad circular membraneous wing, c. 5 cm in diam., testa finely verrucous, dull brown, margin coarsely 8–9-spined. Malaysia Bayabusua

– Fruit indehiscent, much smaller. South and Central America 118

118. Fruit a large, fibrous samara with 1 continuous, encircling wing or small, membranaceous, with two lateral wings Pteropepon

– Fruit baccate, globose, fleshy or fibrous, not winged Sicydium

119. Stamens 4 and 1 staminode 120

– Stamens 5 121

120. Corolla slightly to strongly zygomorphic; ovary 3-locular at the apex, 1-locular at the base; ovules many per locule; fruit a capsule (apically 3-valvate); seeds clearly winged, fusiform. Africa Gerrardanthus

– Corolla actinomorphic; ovary 1-locular; ovules 1 per ovary; fruit a samara; seed compressed; pericarp (wing included) fibrous or membranaceous. South America Pteropepon

121. Petals lanceolate, long acuminate; corolla actinomorphic. Asia Actinostemma

– Petals ovate or oblong, never long-acuminate; corolla not actinomorphic 122

122. Fruit operculate or capsule or opening by longitudinal splits. America 123

– Fruit not operculate. Asia or Africa 124

123. Fruit operculate (rarely a capsule); leaves pedately 3–7-lobed or 3–5-foliolate Fevillea

– Fruit opening by longitudinal splits; leaves simple, entire Anisosperma

124. Fruit fleshy 125

– Fruit dry 127

125. Petals fringed. Tropical Africa and Madagascar Telfairia

– Petals entire 126

126. Plant glabrous or hairy but not glandular. Asia Baijiania

– Plant ± glandular hairy. Tropical Africa or Asia Siraitia

127. Fruit indehiscent, 20–30 cm long; seeds large, 3.5–4 cm long. Asia Indofevillea

– Fruit apically 3-valvate, to 8 cm long; seeds small 128

128. Seeds with wing on the chalazal end; flowers actinomorphic. China, Indomalesia, and Australia Neoalsomitra

– Seeds unwinged or wing encircling the seed, uniform in width or extended along the chalaza-micropyle axis. Asia 129

129. Annual, herbaceous climbers or trailers, to 5 m long with fibrous roots Gomphogyne

– Mostly perennial and tuberous climbers or trailers Hemsleya

130. Filaments connate into a central column 131

– Filaments distinct or connate to pairs only 138

131. Male flowers 4-merous, female flowers 3-merous. Central America Sicyos

– All flowers 5-merous 132

132. Thecae connate into a horizontal, ring-like structure. South and Central America Cyclanthera

– Thecae distinct or connate into a central head-like structure 135

133. Fruits fleshy, unarmed, indehiscent, 1-seeded. Central America Sicyos

– Fruit ± dry, if fleshy, then seeds few to many 134

134. Fruit indehiscent, smooth. Hispaniola Penelopeia

– Fruit dehiscent, ± setose or prickly 135

135. Fruit operculate; seeds relatively small, ± compressed. America Echinopepon

– Fruit not operculate 136

136. Seeds large, ± globose. North and Central America Marah

– Seeds small, ± compressed 137

137. Fruits dry, indehiscent. America, Pacific Islands, Australia, introduced in Africa Sicyos

– Fruits ± fleshy, opening explosively, solitary. Tropical America Hanburia

138. Pollen baculate or echinate 139

– Pollen reticulate or striate 146

139. Fruit indehiscent 140

– Fruit dehiscing 144

140. Fruit fleshy 141

– Fruit dry 143

141. Fruit a small red, ovoid to globose, fleshy berry, c. 1 cm long and 1 cm in diam. Argentina and Uruguay Abobra

– Fruit a fleshy pepo, >5 cm long 142

142. Testa densely appressed hairy, pale yellowish-brown. Central America Tecunumania

– Testa glabrous, smooth, cream-colored or black. America, introduced in Africa, Europe, Asia, Australia Cucurbita

143. Stamens inserted in the center of the flower. Seeds compressed, ovoid or less often ± triangular or dagger-shaped and apically tricornute; tests not banded. Tropical and subtropical America Cayaponia

– Stamens inserted near the mouth of the receptacle-tube. Seeds ovoid, compressed; testa brown or banded crosswise with light and dark stripes. Mexico and Guatemala Schizocarpum

144. Fruit ± ribbed, 5–8 cm long, seeds 6, 12 or c. 48, oblong or obovate, compressed; testa smooth, margin obtuse, not winged. Asia Herpetospermum

– Fruit ± rounded, ellipsoid to pear-shaped, rostrate or not, smooth 145

145. Seeds broadly ovate, compressed, contracted at base; testa brown, narrowly winged. Central America Polyclathra

– Seeds ovoid, compressed, not contracted; testa brown or banded crosswise with light and dark stripes, margin with or without wing. Mexico and Guatemala Schizocarpum

146. Petals fringed 147

– Petals not fringed 150

147. Seeds small. Asia to Australia Trichosanthes

– Seeds large 148

148. Anthers connate into a central globose head. Asia Hodgsonia

– Anthers distinct 149

149. Stamens 5, anthers all 1-thecous. Madagascar Ampelosicyos

– Stamens 3–5, one or several anthers 2-thecous. Tropical Africa and Madagascar Telfairia

150. Stamens 2 151

– Stamens 3 or 5 152

151. Male flowers often subtended by a ± orbicular bract, often 1–3 of the petals with an incurved basal scale; receptacle-tube broadly campanulate. Africa and Asia, introduced in Australia and America Momordica

– Male flowers long pedunculate but without orbicular sheathing bract; receptacle-tube elongate-cylindrical. Peru Apodanthera

152. Stamens 5 153

– Stamens 3 156

153. Seeds pear-shaped to subglobose. Africa, Madagascar, Asia 154

– Seeds ± compressed 155

154. Fruit operculate, the basal part green, expanded into a cup, the upper part red Corallocarpus

– Fruit indehiscent or opening by valves, ripening entirely orange to red Kedrostis

155. Fruit a ± fleshy berry. Asia Thladiantha

– Fruit dry with seeds in fibrous tissue. Africa, Arabia, Asia, Australia, America Luffa

156. Male flowers often subtended by a ± orbicular bract, often 1–3 of the petals with an incurved basal scale; receptacle-tube broadly campanulate. Africa and Asia, introduced in Australia and America Momordica

– Male flowers without prominent, ± orbicular sheathing bract and without petal scales 157

157. Thecae straight or ± curved 158

– Thecae duplicate or triplicate or convoluted 160

158. Seeds 1–3, pendent, ovate, compressed; testa brown, ± sculptured, margin irregularly dentate, not winged. Asia Schizopepon

– Seeds usually more than 3; testa yellowish or brown, ± smooth, margin sometimes distinct but not dentate 159

159. Stamens inserted near mouth of receptacle-tube; seeds often chocolate-brown with distinct ivory-colored margin. America Apodanthera

– Stamens inserted halfway up the receptacle-tube; seeds yellowish or brown but not with distinct, ivory-colored margin. Africa, Asia, Australia, introduced in America Cucumis

160. Thecae duplicate. Tropical Africa Cogniauxia

– Thecae triplicate, flexuose or convoluted 161

161. Petioles with two, ± conspicuous apical glands. Africa, introduced in Asia and America Lagenaria

– Petioles not with paired glands 162

162. Receptacle-tube elongate, tubular to cylindric 163

– Receptacle-tube short, broad, shallow 164

163. Stamens inserted halfway up the receptacle-tube. Asia, Australia, introduced in Africa and America Trichosanthes

– Stamens inserted near the mouth of the tube. Africa and Madagascar Peponium

164. Fruits in clusters or racemes 165

– Fruit solitary (rarely 2–3) 167

165. Fruits up to 8 in racemes, globose, c. 2.5 cm across, with strong gourd-like odor, style and calyx rests persistent on fruit. Tropical West Africa Bambekea

– Fruits in clusters of 2–6, globose, ellipsoid or ovoid, usually <2 cm across, style and calyx not persistent on fruit 166

166. Stamens inserted near the mouth of the receptacle-tube; fruits ripening bright red with silvery white stripes or marks. Africa, Asia, Australia Diplocyclos

– Stamens inserted halfway up the receptacle-tube; fruits ripening yellow, orange, red or greenish to brownish, often with longitudinal pale stripes. Africa, Asia, Australia, introduced in America Cucumis

167. Fruit dry with seeds embedded in fibrous tissue. Africa, Asia, Australia, America Luffa

– Fruit ± fleshy 168

168. Fruit a small, baccate, globose, ellipsoid or ovoid berry with white pulp, ripening bright red with silvery white stripes or marks. Africa, Asia, Australia Diplocyclos

– Fruit a ± large pepo or gourd, if berry, then not with white pulp and bright red pericarp 169

169. Fruit at first hispid, later glabrous, dark green and covered with white wax; seeds many, compressed, smooth, white with thick margin. Asia, Australia, Pacific Islands, introduced in Africa Benincasa

– Fruit not hispid when young, not covered with white wax when older 170

170. Stamens inserted near the mouth of the receptacle-tube. Australia Nothoalsomitra

– Stamens inserted at the base of the tube or halfway up 171

171. Stamens inserted halfway up the tube. Africa, Asia, Australia, introduced in America Cucumis

– Stamens inserted at the base of the tube. Africa, Asia, introduced in Australia and America 172

172. Style filiform; fruit small and globose or cylindrical and to 30 cm long, baccate, usually glabrous Coccinia

– Style short, columnar; fruit large, globose or oblong, glabrous or covered with prominent spines Citrullus

173. Petals fringed 174

– Petals not fringed 175

174. Seeds small. Asia, Australia, introduced in Africa and America Trichosanthes

– Seeds large. Asia Hodgsonia

175. Petals 6. North America Echinocystis

– Petals 3–5 176

176. Male flowers 4-merous, female flowers 3-merous. Central America Sicyos

– All flowers 5-merous 177

177. Pollen reticulate 178

– Pollen echinate, baculate or perforate 181

178. Receptacle-tube elongated, cylindrical 179

– Receptacle-tube (broadly) campanulate 180

179. Thecae triplicate; stamens inserted halfway up the tube. Asia Trichosanthes

– Thecae straight or ± curved; stamens inserted near the mouth of the tube. America Apodanthera

180. Fruit ± fleshy, indehiscent. Africa, Asia, introduced in Australia and America Citrullus

– Fruit dry with fibrous tissue, operculate. Africa, Asia, Australia, America Luffa

181. Filaments connate into a central column 182

– Filaments distinct 188

182. Thecae connate into a horizontal, ring-like structure. South and Central America Cyclanthera

– Thecae distinct or connate into a central head-like structure 183

183. Fruit dry, globose, smooth, 5–7 cm in diam., indehiscent. Hispaniola Penelopeia

– Fruit ± fleshy, if dry, then not globose 184

184. Fruit 1-seeded, fleshy, medium-sized to large. Central America 185

– Fruit few- to many-seeded, if 1-seeded, then fruit dry or small 186

185. Nectaries in open pouches. Mexico Sicyos

– Nectaries often with umbrella-like covering (not in F. tacaco and F. talamancensis). Costa Rica, Nicaragua, Panama Frantzia

186. Fruit explosively dehiscent Hanburia

– Fruit indehiscent or operculate 187

187. Fruits indehiscent, winged or 3–4-angled, small ovoid to fusiform, armed with retrorse barbs or unarmed, glabrous or villous, sometimes enclosed by a subtending leaf; seed solitary, ovoid or tumid to compressed. America, Pacific Islands, Australia, introduced in Africa Sicyos

– Fruits operculate, echinate, rostrate, if indehiscent, then subterranean (to 3.5 cm deep), on 6–9 cm long peduncle (E. arachoidea); seeds solitary or few, quadrangular or angular-ovoid, compressed. America Echinopepon

188. Fruit dehiscent, dry or fleshy 189

– Fruit indehiscent 191

189. Fruit a fleshy pepo, splitting into three carpellar segments at maturity Peponopsis

– Fruit ± dry at maturity 190

190. Fruit splitting into several irregular segments. Central America Polyclathra

– Fruit splitting into 3 valves. Asia Herpetospermum

191. Fruit a dry berry 192

– Fruit a medium-sized to large, fleshy pepo 193

192. Flowers large, solitary in the axils; peduncle of male flowers to 30 cm long, to 15 cm in female; receptacle-tube campanulate to urceolate, ± inflated. South America Calycophysum

– Flowers small, in racemes, panicles, pairs or solitary, male and female often coaxial; receptacle-tube campanulate, not inflated. America Cayaponia

193. Stamens inserted close to the mouth of the receptacle-tube; fruit a globose, ellipsoid or cylindrical pepo, smooth, to 60 cm long. Central America Sicana

– Stamens inserted near the base of the receptacle-tube 194

194. Receptacle-tube and corolla ± campanulate or funnel-shaped. America, introduced in Africa, Europe, Asia and Australia Cucurbita

– Receptacle-tube flat, saucer-shaped, villous; corolla flat, villous outside, smooth inside. Asia Benincasa

Literature:
Schaefer, H. and S.S. Renner. 2011. Cucurbitaceae. Pp. 112-174 in K. Kubitzki (ed.), Families and Genera of Flowering Plants, Vol. 10. Springer Verlag, Berlin.