Trillium luteum aka Yellow Wakerobin

Trillium luteum is a perennial wildflower known as yellow trillium. It belongs to the Melanthiaceae family and grows from rhizomes. Its native range lies in the eastern United States. It grows in the Great Smoky Mountains and nearby areas. Records include North Carolina, Georgia, and Tennessee. Wild plants grow in moist woods and beside streams. They also grow in soils over rocks rich in lime.

Garden plants reach about 0.7–1.5 feet [0.2–0.46 metres] tall. RHS gives an upper size of 1.6 feet [0.5 metres]. Plants spread about 1–1.5 feet [0.3–0.46 metres] across. Thick rhizomes form clumps that expand slowly when left alone. Smooth, straight stems range from green to reddish. Each bare stem ends in a whorl of three bracts. These leaf-like parts have smooth edges and oval shapes. Green and silvery patches mark their surfaces. The foliage dies back, often by the middle of summer. Dry soil can bring this dieback forward.

A single flower sits without a stalk above each whorl. Three narrow petals stand upright above three greenish sepals. The petals are yellow or yellow-green and may twist slightly. Flowers can have a light lemon scent. North Carolina plants flower from March to April. Missouri Botanical Garden gives April to May as the bloom period. Bees, yellow jackets, and other insects visit for pollen and nectar. Green or whitish, berry-like capsules follow, sometimes with purple streaks. North Carolina fruits ripen from May to June. Ants help spread them, while small mammals eat fruits and seeds.

Grow this plant in partial or full shade. It needs rich soil with humus and good drainage. Keep the soil moist with regular watering. RHS recommends acid to neutral soil and an autumn leaf-mould mulch. Sources give USDA zones 4–8 and the UK rating H5. It suits woodland gardens, native gardens, and groups beneath shrubs. Its spring flowers and mottled foliage pair well with ferns. It also hosts the larvae of two moth species. Plants need no pruning, but they dislike being moved. Seed-grown plants can take five to seven years to flower.

Serious pest and disease problems are uncommon. Slugs and snails may feed on the plants. Leaf spot, rust, and smut can occur, and deer browse foliage. NC State lists young, unfolding leaves as edible after cooking. Its guidance calls for ten minutes in boiling, salted water. It also flags the fruits as a low-severity poison concern. The toxic substance and symptoms remain unknown, so safety is uncertain.