Low-growing, spreading, woody-based, herbaceous perennial or sub-shrub which typically forms a foliage mound. It is evergreen in warm winter climates, but semi-evergreen in cold winter climates where the foliage may become straggly or otherwise suffer significant decline in harsh winters. Small, pure white, 4-petaled flowers in dense, flattened clusters (corymbs) appear in a profuse, early-to-late-spring bloom. Flowers sometimes gradually age to light pink.