Trillium sessile, the toadshade<ref>Template:PLANTS</ref> or sessile-flowered wake-robin, is a perennial spring wildflower native to the central part of the eastern United States and the Ozarks.<ref name=r/><ref name=b/><ref>Biota of North America Program 2014 county distribution map</ref> It is a small trillium (rarely over 9 cm tall). Toadshade can be distinguished from other trilliums by its single foul smelling, stalkless, flower nestled in the middle of its three leaves. The three maroon petals, maintain a "closed" posture throughout its presence, the petals are occasionally pale green. The leaves are sometimes, but not always mottled with shades of light and dark green. Its species name comes from the Latin word sessilis which means low sitting, and refers to its stalkless flower.<ref name=b/>
Trillium sessile is most common in rich moist woods but also can be found in rich forests, limestone woods, flood plains, along fence rows. It is persistent under light pasturing.<ref name=b>Flora of North America: Trillium sessile</ref> The foul smelling flowers attract its primary pollinators, flies and beetles.<ref>Missouri Plants: T. sessile</ref> The flowers are present from April–June. This plant is clump forming from a thick rhizome. The above ground parts of the plant die back by mid-summer, but may persist longer in areas that do not completely dry out.<ref name=b/>
Uncommon, green flowered forms of this plant are sometimes classified as Trillium sessile forma viridiflorum (Beyer). The term Trillium sessile var. luteum used by some nurseries may cause confusion, since this is an older synonym for Trillium luteum, not of T. sessile.
Although some accounts indicate that the cooked greens of this plant may be edible as an emergency food, the entire plant, and especially the root, is known to induce vomiting. The fruit is considered a suspected poison.<ref>ILLINOIS PLANT INFORMATION NETWORK: Trillium sessile</ref> This plant has been used medicinally to treat tumors.<ref>James Duke's Phytochemical and Ethnobotanical Databases: T. sessile.</ref> T. sessile is sometimes cited as having been used as a poultice for boils and as a panacea-like decoction, but this is doubtful as it is attributed to Native American tribes (the Yuki and Wailaki) of California, where this plant is not known to occur.<ref>Dr. Moerman's Native American Ethnobotanical Database: T. sessile</ref>
This plant is sometimes used in woodland wildflower gardens. Like many trilliums, T. sessile often does not transplant successfully from the wild.<ref>Missouri Botanical Gardens: Kemper Garden Center: Trillium sessile</ref>