Echinocystis Torr. & A.Gray

Plants annual, monoecious, climbing or trailing; stems glabrate; taprooted with branching secondary roots or roots slender-fibrous; tendrils 3-branched. Leaves: blade depressed-orbiculate to suborbiculate or ovate, palmately (3–)5(–7)-lobed, lobes triangular to oblong-triangular, margins entire or serrulate-cuspidate, surfaces eglandular, <glabrous or scabrous>. Inflorescences: staminate flowers 50–200 in axillary racemes or racemoid panicles; pistillate flowers 1(–3) from same axils as staminate, <peduncles erect at apex>; bracts absent. Flowers: hypanthium shallowly cupulate; sepals (5–)6, filiform, almost pricklelike; petals (5–)6, connate 1/4 length, white to greenish white, narrowly triangular to linear-lanceolate or oblong-lanceolate, 3–6 mm, minutely glandular-puberulent, corolla rotate. Staminate flowers: stamens 3; filaments inserted at corolla base, connate, <column 0.4 mm>; thecae connate, forming subsessile capitate androecium but not fused into single ring, sigmoid-flexuous, connective broad; pistillodes absent. Pistillate flowers: ovary 2-locular, subglobose; ovules 2 per locule; style 1, nearly vestigial; stigma 3, forming a subglobose head; staminodes absent. Fruits pepos, light green to blue-green, globose-ovoid to ovoid or ellipsoid, bladdery-inflated, symmetric, <dry, thin-walled>, surface moderately to densely echinate, <spinules weak, flexible, whitish-glaucous with green mottling at bases>, dehiscence apically irregularly lacerate, sometimes explosively. Seeds 4, broadly oblong-ellipsoid, strongly flattened, not arillate, margins not differentiated, surface slightly pitted-roughened. x = 32.