A perennial, 1.5–6 dm tall, with an erect, smooth stem growing from a thick, short rhizome, which is up to 3 cm thick. A whorl of 3 sessile leaves is borne at the top of the stem. Leaves are broadly ovate, 5–20 cm long and nearly as wide, smooth on both surfaces, bases are tapering ; apices are sharply pointed; margins are entire.
Bisexual; the single terminal flower is stalked, flower stalk (peduncle), to 10 cm long. Flowers ill-scented; sepals 3, green to tinged with maroon, lanceolate, the tip sharply pointed, 1–5 cm long; petals 3, usually deep red, but may be creamy white or various shades of faded red (as in the image above), oblong-ovate, 1–5 cm long; stamens 6; the single pistil with a 6-angled, ovoid, dark red, superior ovary, 0.5–1 cm long. Flowers bloom in May and early June.
Rich deciduous woods. The red trillium is native to northeastern North America. Trillium erectum is found throughout southern Ontario; it occurs north to the Ottawa District and barely extend into northeastern Ontario, near the Lake Nipissing area. Trillium erectum is the only red-petalled trillium in Ontario.
Taken in Ottawa, Ontario, Canada