Annual herbaceous vine to 6 m or longer Stem: slender, high-climbing, angled, sometimes hairy at nodes. Leaves: alternate, long-stalked, 7 - 13 cm long, heart-shaped to egg-shaped or nearly circular, having three to seven deep lobes (usually five) with pointed tips, non-toothed or few-toothed. Flowers: either male or female, found on the same plant (monoecious), greenish-white, the calyx with six bristle-like lobes, the corolla flat and circular in outline and ending in six lance-shaped lobes. Male and female flowers are borne in the same leaf axils, but the male flowers are arranged in a 30 - 40 cm long inflorescence while the female flowers are solitary or in pairs. Fruit: green, 3 - 5 cm long, egg-shaped, fleshy at first, becoming dry and papery, inflated, covered with slender weak spines, opening irregularly at the tip, releasing four seeds. The flattened seeds are brownish and 1.2 - 1.5 cm long with a hard and roughened coat. Tendrils: branched.
Similar species: Sicyos angulatus differs by having shallowly lobed leaves, a five-lobed corolla, and fruit that is not inflated, does not open at maturity, and contains a single seed.
Flowering: late July to early October
Habitat and ecology: Frequent in low areas such as floodplains and moist thickets.
Occurence in the Chicago region: native
Notes: Echinocystis lobata was once cultivated to cover arbors or fences and has been known to escape fom gardens.
Etymology: Echinocystis comes from the Greek words echinos, meaning hedgehog, and kystis, meaning bladder, referring to the prickly fruit. Lobata means lobed.
High-climbing annual; lvs long-petioled, orbicular in outline, with (3-)5(-7) sharp, triangular lobes; staminate fls in long erect racemes, the cor 8-10 mm wide, with lanceolate lobes, the pistillate few or solitary, short- peduncled from the same axils; fr ovoid, 3-5 cm, green, weakly prickly; 2n=32. Moist ground and thickets, throughout our range and s. to Fla. and Tex.; often cult. July-Sept. (Micrampelis l.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.