This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol3", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Mostly annual climbing herbs, with branched tendrils, lobed or angled leaves, and small white monoecious flowers. Calyx-tube campanulate, 5-6-lobed. Corolla very deeply 5-6-parted. Stamens 3 in the staminate flowers, the anthers more or less coherent. Pistillate flowers with a 2-celled ovary; ovules 2 in each cavity; style very short; stigma hemispheric or lobed. Fruit fleshy, or dry at maturity, densely spiny, 1-2-celled, usually with 2 seeds in each cavity, dehiscent at the summit. Testa of the seed roughened. [Greek, small-vine.]
About 25 species, natives of America. Besides the following typical one, about 10 others occur in the western United States.
Stem nearly glabrous, angular and grooved, branching, climbing to a height of 15°-25°, sometimes villous-pubescent at the nodes. Petioles 1'-3' long; leaves thin, roughish on both sides, deeply cordate at the base, 3-7-lobed to about the middle, the lobes triangular-lanceolate, acute or acuminate, the margins remotely serrulate; staminate flowers very numerous in narrow compound racemes; pistillate flowers solitary, or rarely 2 together; fruit ovoid, green, about 2' long, armed with slender spines; seeds flat.
Along rivers, and in waste places, New Brunswick to Ontario, Manitoba, Montana, Virginia, Pennsylvania, Kentucky, Kansas and Texas. Eastward, mostly occurring as an introduced plant. Wild cucumber. Creeper. Creeping Jenny. July-Sept.