Wild cucumbers are members of either one of two plant groups with that common name. Both are natives of North America. Members of the Marah genus, collectively called wild cucumbers, are found on the west coast from British Columbia south through California and nearby states. Echinocystis lobata is found in all Canadian provinces and most US states outside of California. Both plants are members of the Cucubitceae, or cucumber, family, with climbing vines and spiny fruits that resemble those of garden cucumbers but are not edible.
Species in the Marah genus, the wild cucumbers found on the West coast of North America, are perennial vines that grow from a very large underground tuber. These tubers can weigh up to 100 pounds (45.5 kg) in some species and are the source of the alternate common name, "manroot." These wild cucumbers are found primarily in dry regions including Nevada, New Mexico and Arizona. They generally grow below 6,000 feet (about 1,829 m) in elevation.
Wild cucumbers of this genus are climbing vines that use twining tendrils to climb over shrubbery and trees. The leaves are large, with five to seven lobes, or rounded divisions, which are subdivided by smaller lobes. Small cup-shaped white flowers have five petals each. The fruits are round to oval-shaped and range from 1.5 to 8 inches (about 4 to 20 cm) depending on species and growing conditions. Sharp spines cover the fruits, which split and spill the seeds when ripe.
Echinocystis lobata, the other species of wild cucumber, is found throughout Canada and in most of the United States except California, Nevada and states in the Southeast. Alternate common names include wild mock cucumber, prickly cucumber and wild balsam apple. This species of wild cucumber grows most readily in areas of high soil moisture including swamps and along rivers as well as in shrub lands and forests with sufficient rainfall.
These wild cucumbers are annual vines and, like those from the Marah genus, tend to climb shrubbery and trees. They have thick stems and large star-shaped leaves with five divisions. Small white six-petaled flowers grow in groups along the vine. Female flowers are slightly larger and interspersed with the more numerous male flowers. The green, round fruits are 1 to 2 inches (about 2.5 to 5 cm) long and are thickly covered with spines. When ripe the fruits open and expel the four hard, dry seeds.