Ruellia simplex is an evergreen perennial growing 3 ft (0.91 m) tall, forming colonies of stalks with lance-shaped leaves that are 6 to 12 in (15 to 30 cm) and . 5 to . 75 in (1.3 to 1.9 cm) wide. Trumpet shaped flowers are metallic blue to purple, with five petals, and 3 in (7.6 cm) wide.
