Ruellia simplex - Mexican petunia is an attractive blue- to purple-flowered perennial available at some garden centers. Gardeners have traditionally used Mexican petunia to add height to perennial borders since it can grow up to three feet tall.

However, in Florida, Mexican petunia (Ruellia simplex*) has been classified as a highly invasive plant. Their underground rhizomes can become difficult to manage in ideal growing conditions, and these plants also spread via seeds.