Somewhat fleshy herbs, perennial by rootstocks. Leaves cauline, whorled, or sometimes solitary long-petioled ones are borne on the rootstock. Flowers terminal, solitary or umbelled, sessile or pedicelled, perfect. Perianth of 3 separate sepals and 3 separate petals. Stamens 6; anthers 2-celled. Ovary sessile, 3-celled; styles 3, stigmatic along the inner side; ovules several or numerous in each cavity. Fruit a globose or 3-lobed berry.

Three genera and about 25 species, natives of the north temperate zone.

Leaves in 2 (rarely 3) whorls; flowers umbelled.

1.

Medeola.

Leaves in 1 whorl; flowers solitary.

2.

Trillium.