Trillium cernuum is a perennial herbaceous member of the Melanthiaceae, named for its drooping spring flower that sits beneath the leaves. It originates from eastern and central Canada, recorded from Newfoundland, Manitoba, New Brunswick, Nova Scotia, Ontario, Prince Edward Island, Quebec and Saskatchewan. Flowering is in April to May and the species prefers sheltered, shaded positions with moist, rich, loamy, acidic to neutral soil on a north or east aspect.

Drooping Wake-Robin (Trillium cernuum) is a woodland perennial with nodding April–May flowers for sheltered, moist, acidic to neutral soil in shade.

https://en.wikipedia.org/wiki/Trillium_cernuum

Trillium is a genus of about fifty flowering plant species in the family Melanthiaceae. Trillium species are native to temperate regions of North America and Asia, with the greatest diversity of species found in the southern Appalachian Mountains in the southeastern United States.

Trillium cernuum

Drooping wake-robin | Trillium cernuum

Trillium chloropetalum is a perennial herbaceous woodland plant valued for its spring-scented flower. It prefers partial shade to full shade and thrives in rich, moist, well-drained loamy soil with an acidic to neutral reaction. Position it on a sheltered north- or east-facing aspect where soil moisture can be maintained. Flowering takes place April to May.

Giant Wake-Robin (Trillium chloropetalum) is a scented woodland perennial that flowers April to May and prefers rich, moist loam in shade.

https://en.wikipedia.org/wiki/Trillium_chloropetalum

Trillium chloropetalum

Giant wake-robin | Trillium chloropetalum

Trillium erectum is a perennial herbaceous plant in the Melanthiaceae, noted for its musky-scented spring flowers. It grows to about 0.4 m and flowers in the UK from April to May. It suits shaded or part-shade positions and prefers moist but well-drained soil with an acidic to neutral pH. All parts of the plant are toxic if ingested.

Birthroot (Trillium erectum) is a spring-flowering perennial for shaded and part-shade sites, flowering April to May and toxic if ingested.

https://en.wikipedia.org/wiki/Trillium_erectum

Trillium erectum

Birthroot | Trillium erectum

Trillium erectum 'Album' is a perennial in the Melanthiaceae grown for its single white flowers and compact 0.4 m height. It blooms in the UK from April to May. The plant suits positions from full sun to full shade and prefers moist but well-drained sandy, loamy or clay soils. It is fully hardy (H7) and also falls within USDA zones 4–9.

White Trillium (Trillium erectum 'Album') produces white flowers in April–May on a 0.4 m perennial suited to full sun or full shade in moist, well-drained.

Trillium erectum 'Album'

White Trillium | Trillium erectum 'Album'

Trillium erectum 'Ochroleucum', or 'Viridiflorum' is a perennial herbaceous Trillium reaching about 0.4 m. It flowers in April to May. The cultivar tolerates full sun through to full shade and grows in sandy, loamy or clay soils that remain moist but well-drained. It is fully hardy (H7) and native to parts of eastern Canada.

Trillium erectum 'Ochroleucum', or 'Viridiflorum' is a perennial Trillium that flowers in April to May and prefers moist, well-drained soil in sun or.

Trillium erectum 'Ochroleucum', or 'Viridiflorum'

Trillium erectum red-flowered is a clump-forming herbaceous perennial in the Melanthiaceae, notable for its red-flowered display in spring. It carries a whorl of three deciduous leaves and forms compact colonies. Plant in partial shade on moist but well-drained loam or sandy soils in a sheltered north-, east- or west-facing position where it is hardy (H5). Flowers appear April to May.

Red Trillium (Trillium erectum red-flowered) favours partial shade on moist, well-drained loam or sand and flowers April to May.

Trillium erectum red-flowered

Red Trillium | Trillium erectum red-flowered

Trillium grandiflorum is a perennial herb notable for its three-petalled white flowers that sit above a whorl of three leaf-like bracts. It grows to about 0.4 m and emerges in spring before the canopy fills. Plants prefer a shaded, sheltered position with consistently moist, well-drained soil. Flowers appear in April to May in the UK.

American wake-robin (Trillium grandiflorum) is a shade-loving woodland perennial that flowers in April to May.

https://en.wikipedia.org/wiki/Trillium_grandiflorum

Trillium grandiflorum

American wake-robin | Trillium grandiflorum

Trillium grandiflorum 'Flore Pleno' is a perennial woodland plant that produces conspicuous white flowers in April to May and reaches about 0.4 m. It prefers moist but well-drained soils across sandy, loamy or clay types and tolerates full sun to full shade. Fully hardy in the UK (H7), it is native to Nova Scotia, Ontario and Quebec. Plant in locations where summer soil moisture remains reliable.

Trillium grandiflorum 'Flore Pleno' produces white flowers in April to May and prefers moist, well-drained soil in full sun or full shade.

Trillium grandiflorum 'Flore Pleno'

White Trillium | Trillium grandiflorum 'Flore Pleno'

Trillium grandiflorum 'Roseum' is an herbaceous perennial in the Melanthiaceae valued for its rose-coloured flowers. Plants form low clumps to about 0.4 m in height and flower in April to May. It tolerates a wide light range from full sun to full shade and prefers moist but well-drained soils.

Rose-coloured wake-robin (Trillium grandiflorum 'Roseum') flowers in April to May and suits moist, well-drained soils in full sun to full shade.

Trillium grandiflorum 'Roseum'

Rose-coloured wake-robin | Trillium grandiflorum 'Roseum'

Trillium kamtschaticum is a perennial herbaceous member of the Melanthiaceae, reaching about 0.3 m and flowering in April–May. It comes from Japan, Korea, China and eastern Russia. The plant tolerates light from full sun to full shade and suits sandy, loamy or clay soils that stay moist but drain freely. It is fully hardy in the UK (H7) and corresponds roughly to USDA zones 4–8.

Kamchatka Trillium (Trillium kamtschaticum) is a perennial from East Asia flowering in April–May and suited to moist, well-drained soils.

https://en.wikipedia.org/wiki/Trillium_camschatcense

Trillium kamtschaticum

Kamchatka Trillium | Trillium kamtschaticum

Trillium luteum is a perennial herbaceous plant in the Melanthiaceae, notable for its yellow, mildly sweet-scented flowers. It flowers in April to May. The plant prefers partial to full shade and moist, rich, well-drained loamy soil with an acidic to neutral pH. A sheltered north- or east-facing aspect suits it and it is useful for woodland, shade gardens and naturalising.

Yellow Wood Trillium (Trillium luteum) is a woodland perennial with mildly sweet-scented yellow blooms in April to May.

https://en.wikipedia.org/wiki/Trillium_luteum

Trillium luteum

Yellow wood trillium | Trillium luteum

Trillium nervosum is a spring-flowering member of the genus Trillium in the Melanthiaceae. It produces its blooms in April to May and is noted among growers for a single-season display of flowers. The species is associated in horticultural literature with woodland planting and specialist spring collections. It is also referred to by the common names Lily and Wood.

Trillium nervosum flowers in April to May and suits shaded, humus-rich sites in a woodland-style border.

https://en.wikipedia.org/wiki/Trillium_catesbaei

Trillium nervosum

Trillium ovatum is a perennial herbaceous plant in the Melanthiaceae that produces a single three-petalled spring flower. It reaches about 0.4 m in height and is native to western North America. Flowers appear in April to May and the blooms are fragrant. Plants tolerate a wide light range from full sun to full shade on moist, well-drained soils.

Western Wakerobin (Trillium ovatum) blooms in April to May with fragrant white flowers and prefers moist, well-drained soils in sun or shade.

https://en.wikipedia.org/wiki/Trillium_ovatum

Trillium ovatum

Western wakerobin | Trillium ovatum

Trillium ovatum 'Kenmore' is a perennial in the Melanthiaceae that produces its spring flowers in April to May and reaches about 0.4 m. It originates from western North America and is valued for its single seasonal display. It suits shaded or partially shaded sites and prefers moist but well-drained soils. Planting in shade helps it show best in spring.

Trillium ovatum 'Kenmore' flowers in April to May and suits moist, well-drained soils in shade or partial shade.

Trillium ovatum 'Kenmore'

Trillium undulatum is a perennial herbaceous member of the Melanthiaceae, growing to about 0.2 m and flowering in April to May. Native to eastern North America, it suits shaded or semi-shaded sites and is recommended for woodland and shade gardens. Plant in moist but well-drained soils that are acidic to neutral; it tolerates sandy, loamy or clay textures. With an H7 hardiness rating it is fully hardy across the UK.

Painted trillium (Trillium undulatum) is a low, spring-flowering perennial for shaded UK gardens, flowering April to May.