Ruellia nudiflora

The wild petunia has flowers much like those of the cultivated petunia (genus Petunia, family Solanaceae). The plants are erect, 1-2 feet tall, with few branches. The leaves are opposite, 2-5 inches long, narrowed at the base, on short stems. Gray-green leaves have curly or wavy-toothed margins. At the top of the plant are several trumpet-shaped, purplish blossoms that are nearly 2 inches across at the opening. Flowers are lavender to purple, trumpet-shaped, deeply lobed at the flared rim, and open about sunrise, falling from plant in early afternoon, lasting only one day.
This genus Ruellia is not the petunia common as potted plants which are in the Solanaceae (Potato Family). This genus of wild petunias is in the Acanthaceae (Ancanthus) Family.

Water moderately, allowing the top 3cm to dry out between watering.