Rhizomes horizontal, brownish, thick, short, praemorse, not brittle. Scapes 1-2, green to maroon, round in cross section, 0.8-2.8 dm, papillose basally. Bracts often carried quite horizontally, well above ground, sessile; blade light green or bronze-green, strongly mottled in dark green with central light green stripe, mottling becoming obscure with age but less so than in most species, elliptic-ovate, rarely ± orbicular, 6.7-12 × 3.8-6 cm, not glossy, base evenly tapered to broad attachment, apex obtuse-acute. Flower borne directly on bracts, odor of putrid meat, especially when in strong sunlight; sepals displayed above bracts, carried almost horizontally, green or green streaked with dark maroon, lanceolate, 16-40 × 4-6 mm, thick-textured, margins entire, apex acute; petals long-lasting, erect, very gradually incurved from base to apex, ± connivent, ± concealing stamens and ovary, pinkish purple, light to reddish purple, brownish purple, rarely yellow, fading to brownish tones with age, not spirally twisted, not inrolling with age, veins not engraved, narrowly elliptic to linear-lanceolate, 2-5 × 0.3-0.5 cm, thick-textured, not glossy, margins entire, flat, acute at apex; stamens relatively prominent, erect, 9-25 mm; filaments dark maroon, 3-6 mm, dilated basally; anthers straight, dark maroon-black, 8-15 mm, dehiscence introrse; connectives straight, extended 1-1.5 mm beyond anther sacs; ovary red-purple, ovoid, hexagonal in cross section, 5-12 mm, broadly attached; stigmas erect, divergent-recurved, distinct, dark purple, subulate, nearly as long as ovary, fleshy. Fruits purplish brown, ovoid, 6-angled at least apically, fleshy.

Flowering late winter--early spring (early Mar [rarely Feb]--early Apr). River bluffs, ravines, floodplains, low ground, rich woods, road shoulders, silts, sandy-alluvium, loess soils, drier upland oak and pine woods; 40--50 m; La., Miss.

Trillium foetidissimum seems tolerant of a wide range of soil moistures and types, from low, swampy woods to high, dry bluffs and ravine slopes. This is the only Trillium known to occur within its Louisiana range (J. D. Freeman 1975). Freeman considered it to be closely related to T. sessile.