Brook Lettuce, a native species, has been added to the USWildflowers database (09/16/2015.)  Scientific name is Micranthes micranthidifolia. Photo below was taken along the Little River Trail in the Great Smoky Mountains National Park on May 04, 2015. Go to the Brook Lettuce detail page for more photos and information.

Brook Lettuce – Micranthes micranthidifolia