Members of this family are sometimes superficially confused with the Caryophyllaceae, but differ in having the petals united, the style solitary, and the ovary 3-locular. The gross aspect of the flowers in a cymose inflorescence, together with the simple, opposite, and entire leaves (in Phlox), does indeed suggest a “pink.”
1. Leaves simple, entire.
2. Leaves all alternate, the uppermost (large bracts) overtopping the inflorescence; corolla ca. 3–6 mm broad; annual weed of disturbed ground.
2. Leaves, at least lower ones, opposite, the uppermost (tiny bracts) much shorter than the inflorescence; corolla (8–) 11–30 (–42) mm broad; perennials (except for P. drummondii).
1. Leaves pinnately compound or dissected.
3. Corolla red; leaves dissected, with filiform segments.
3. Corolla blue (except in albinos); leaves compound, with lance-elliptic leaflets.