Winter annual, less than 12-in. tall; noticeable in spring for pink to purple flowers.
Square stems; leaves opposite, scalloped, and rounded; lower leaves with petioles, upper leaves half encircling the stem; pinkish-purple, lipped flowers in whorls in the axils of upper leaves; fibrous root system that does not creep along the ground.
Seed germinating in early fall or early spring.
Conditions that favor growth
Mowing the lawn too short and improper fertilization.