By Mayday woodland hillsides are covered with enormous colonies of this beautiful flower, especially in stream valleys. This one grew along the aptly named Trillium Trail in Fox Chapel; another large colony grows on a hillside in the Allegheny Cemetery in Lawrenceville. The genus Trillum has been variously placed in the families Liliaceae and Trilliaceae, but botanists finally seem to have settled on placing it in the family Melanthiaceae, where doubtless it will find a good home.
From Gray’s Manual of Botany: Trillium grandiflorum (Michx.) Salisb. Leaves less broadly rhombic-ovate; pedicel erect or ascending ; petals oblanceolate, often broadly so (4-6 cm. long), white turning rose-color or marked with green ; stamens with stout filaments (persistently green about the fruit) and anthers, exceeding the very slender erect or suberect and somewhat coherent stigmas; fruit subglobose. Rich woods, w. Que. and w. Vt. to Minn., Mo., and N. C.