Wild blue phlox

Phlox divaricata is a herbaceous perennial valued for its lavender-blue flowers, native to forests and fields in eastern North America.
Wild phlox grows 25-50 cm tall with opposite, unstalked leaves 2.5-5 cm in length and ovate-lanceolate in shape.
Flowers appear in early spring and are 2-4 cm in diameter, with five petals fused at the base into a thin tube.