Flowers solitary, arising stemless from a whorl of leaves. Colors variable: brown, brown-purple, maroon, brick-red, brownish-yellow, greenish-yellow, greenish, or a mixture with green. Flower with 3 sepals and 3 petals; upright; to about 2 inches tall. Blooms April-June. Leaves 3 in a whorl, topping a bare stalk to 1 foot tall, ovate, pointed, sessile (lacking leaf stalks), dark green with or without grayish mottling. Root a short rhizome. Fruits many-seeded berries.
Missouri has 7 species in the genus Trillium. Purple trillium (T. recurvatum) is similar to T. sessile, but the sepals curve downward as the flower opens, and the leaves have a distinct, short stem; it is the most common trillium in eastern Missouri. Green trillium (T. viride) is taller, with sepals spread outward; petals erect, to 3 inches long, green or yellow; leaves broadly lance-shaped or nearly round, green or mottled; common in southwestern and east-central Missouri.