Description: This native perennial plant
consists of a twining vine up to 20-30' long. It will climb adjacent vegetation
readily, or sprawl across the ground in open areas. The stems are usually
hairless, but sometimes pubescent, and often reddish purple. Along the stems
are alternate leaves up to 6" long and 4" across. These leaves are usually
cordate and hairless, although sometimes the smaller leaves are ovate. They
have long petioles and smooth margins. From the upper axil of the leaves, a
flowering stalk may appear with 1-5 funnelform flowers. The corolla of these
flowers is white, except for rosy pink or reddish purple coloration deep within
the throat. The corolla has 5 shallow lobes; it is about 3" across when fully
open. The stamens of the flower are white; they project slightly from the
throat. The blunt sepals are light green, hairless, and about
½–¾" long. These flowers bloom during the morning (or during
the afternoon on cloudy days), and are individually short-lived. However, a
typical plant will bloom for about 2 months during mid- to late summer. Each
flower is replaced by a 2-celled capsule containing from 2-4 seeds. These flat
seeds are conspicuously hairy along the edges, and pubescent elsewhere. The
root system produces large tubers that can lie several feet beneath the ground
surface and weigh up to 20-30 lb.
Cultivation: The preference is partial to full sun,
and mesic to dry conditions. The type of soil is not particularly important;
this plant often grows where there are rocky or gravelly slopes. Growth can be
rampant where the soil is moist and fertile; this plant can smother surrounding
vegetation, and prefers some kind of structural support. Drought resistance is
very good.
Range & Habitat: The
Wild Sweet Potato occurs occasionally in most counties of Illinois, except in
the extreme north and NW areas of the state, where it is uncommon or absent
(see
Distribution
Map). Habitats include upland woodlands, edges of prairies near woodlands
or rocky streambanks, thickets, fence rows, abandoned fields, and areas along
railroads and roadsides. This plant is more often seen in disturbed habitats,
but can be found in higher quality habitats as well. 
Faunal
Associations: The flowers primarily attract long-tongued bees,
including honeybees, bumblebess, and Miner bees. Some oligolectic bees that
visit the flowers of the Wild Sweet Potato and other members of the Morning
Glory family include Melitoma taurea (Mallow Bee), Cemolobus
ipomoea (Morning Glory Bee), Peponapis pruinosa pruinosa (Squash
& Gourd Bee), and Xenoglossa strenua. These insects seek nectar
primarily, but may collect pollen as well. Less common visitors to the flowers
include nectar-seeking Swallowtail butterflies, skippers, and Sphinx moths.
Members of the Morning Glory family attract their own assortment of insects,
including Chelymorpha cassidea (Argus Tortoise Beetle) and Emmelina
monodictyla (Common Plume Moth). The foliage is not eaten by mammalian
herbivores when other sources of food are available.
Photographic Location: The photographs were taken
near an abandoned railroad in Champaign County, Illinois. The plant was growing
along a gravelly slope, where it clambered over Conium maculatum (Poison
Hemlock).
Comments: The common name
of this plant species refers to the large tuberous root, which is edible after
being cooked. Another common name, Man-of-the-Earth, also refers to this large
tuberous root. It was one of the food sources of native Amerindians. The Wild
Sweet Potato is fairly easy to distinguish from other members of the Morning
Glory family by its large white flowers with purple or pink throats, and the
heart-shaped leaves. Perhaps its most unusual feature (aside from the root) is
the hairiness of the seeds; other Morning Glory and Bindweed species usually
have smooth seeds.