PlantFiles: Painted Trillium
Trillium undulatum

these plants are spectacular and they tend to grow everywhere here in Vermont. i saw one plant with six leaves!

From William Cullina's Growing and Propagating Wildflowers of the United States and Canada:

Quoted:

Painted Trillium is a striking species, with pure white, upward-facing flowers with a prominent triangle of red-purple in the throat that bleeds up along the veins of the petals to the tips. The fruit is a distinctive, smooth oval berry with a pointed tip. Painted Trillium is a common species in northern New England and southeastern Canada, but is very difficult to grow in cultivation, needing consistently moist, cool, acid soils and especially prone to rots in less than ideal conditions. I include it because this is a species often wild collected and sold as "nursery propagated", but you can be 99 percent sure that no nursery is really successfully propagating it. Please enjoy it in the wild".

I was fortunate to have large stands of this plant growing on the property I used to own in Maine. In early spring, its distinguishing feature is the bronze-green foliage versus the green of other Trilliums in the area.