The specific epithet cernuum means "drooping, curving forwards, facing downwards",[3] a distinctive habit of its flower.

[6] It is also called the whip-poor-will flower since presumably its bloom coincides with the spring arrival of the migrating bird with the same name.

Trillium cernuum is found on rich, moist soils in both broadleaf and coniferous woodlands.

Trillium cernuum is a perennial herbaceous plant that spreads by means of an underground rhizome.

[8] A solitary flower hangs below the bracts (leaves) on a short recurved pedicel 1.5–3 cm (0.6–1.2 in) long.

Within its natural range, T. cernuum is often confused with two sympatric Trillium species, T. erectum and T. flexipes.

More importantly, the pedicel of T. cernuum is strongly recurved below the leaves while the other two species rarely exhibit this behavior.

[13] Linnaeus gave the location of his type specimen as "Carolina" but T. cernuum (in the modern sense) does not range that far south.

In 1906, Gleason shed some light on the confusion by showing how to distinguish T. cernuum from T. flexipes on the basis of anther-filament ratio.

[14] Finally, in 1938, Barksdale showed conclusively that the specimen described by Linnaeus was actually T. catesbaei and that T. cernuum is absent from the southern Appalachian Mountains.

[19] The range of Trillium cernuum extends across Canada, from Saskatchewan in the west to Newfoundland in the east, and as far south as northern Virginia in the mid-Atlantic United States.

The species is known to occur in the following provinces, states, and territories:[2][4][20] At the southern end of its range, T. cernuum grows in rich, cool, moist to swampy deciduous woods, and along shrubby stream banks and pond edges of deep forests.