Saxifrage family (Saxifragaceae)
There are two varieties of foamflower in the Eastern United States – var. cordifolia, which occurs in the Catskills and is a running form, producing above ground stolons and slowly forming a groundcover, and var. collina, which occurs from Maryland to Kentucky south to Mississippi and Georgia and is a clumping form. T. cordifolia var. collina is often also listed as T. wherryi in horticulture though that is simply a botanical synonym not a different species.
Most of the clumping forms of foamflower so popular in the nursery trade are not simple selections of T. cordifolia var. collina but instead are hybrids between that species and T. cordifolia var. cordifolia; a western species, T. trifoliata, has also been involved in the parentage of many cultivars. So we list clumping cultivars as “Tiarella x” indicating their unknown hybrid origin.
Updated 29 September 2023