Trillium luteum

Trillium luteum, the yellow trillium or yellow wakerobin, is a species of flowering plant in the bunchflower family Melanthiaceae with native populations in the Great Smoky Mountains of the United States and surrounding areas. 
Description.
Growing to tall by wide, it is a woodland herbaceous perennial flowering in spring, with lemon yellow scented blooms. The large stalkless triple leaves often have grey-green marbling on the surface. It flowers in April-May beneath the bare branches of deciduous trees. After flowering and setting seed it goes dormant in summer, before appearing again in late winter.
Taxonomy.
"Trillium luteum" was first described by Muhlenberg in 1813 as "T. sessile" var. "luteum" but the taxon was later given specific rank by Harbison. Given this history, it's not surprising that "T. luteum" is often sold under the name of "T. sessile "var." luteum", which has caused some confusion. It has also been known as "T. cuneatum "var." luteum" and "T. viride "var." luteum" .
Distribution.
"Trillium luteum" has interbred extensively with "T. cuneatum" in its native range, forming numerous intermediate hybrids. Moreover, botanists in the past have confused it with the more western "T. viride". It is therefore sometimes difficult to determine the true range of purebred "T. luteum" specimens. The main population appears to reside in Eastern Tennessee, extending into North Carolina and Georgia. It is especially abundant around Gatlinburg. The species also occurs in Kentucky, and in scattered locations farther north, in Ontario, Michigan, Pennsylvania, Maryland and northern Virginia, but these appear to be naturalized populations.
Cultivation.
Though hardy down to , this plant requires a sheltered position with rich, moist leafmould in a shaded, deciduous woodland setting which mimics its native habitat in North American broadleaf forests. It must be left undisturbed to grow into a large colony. It requires some experience to grow successfully, but nevertheless has gained the Royal Horticultural Society's Award of Garden Merit.