Wild Petunia - Ruellia sp.

• Flowers: Trumpet shaped, purplish blossoms that are nearly 2 inches across at the opening [Loughmiller].
• Leaves: Opposite, 2-5 inches long, narrowed at the base [Loughmiller].
• Perennial.

Sources:
Loughmiller. Texas wildflowers.
Photo: Courtesy of S. Peregrine Johnson