Trillium (trillium, wakerobin, tri flower, birthroot) is a genus of about 40–50 species of spring ephemeral perennials, native to temperate regions of North America and Asia.
It used to be treated in the family Trilliaceae or trillium family, a part of the Liliales or Lily order. The APG II treats Trilliaceae as a synonym of the family Melanthiaceae.