Phlox carolina

Phlox carolina, the thickleaf phlox, is a species of flowering plant in the family Polemoniaceae. It is an herbaceous perennial growing to tall by wide, with leaves to long, and purple or pink flowers in summer.
The specific epithet "carolina" refers to its native habitat in the eastern United States.
It is the parent of numerous garden cultivars, of which 'Bill Baker' (pink) and 'Miss Lingard' (pure white) have gained the Royal Horticultural Society's Award of Garden Merit. 