Plant Profile: Ruellias

By Craig Huegel

Reprinted from The Understory, 1997

Ruellia, also known as wild petunia, is a widespread wildflower throughout Florida and the Southern Coastal Plain. At least one native species and one widespread non-native occur here in our area. All species are perennials with light lavender petunia-like funnel-shaped flowers and herbaceous foliage. Major differences that assist in identifying the species from each other are found in the shape and color of the leaves.

Ruellia caroliniensis Our native ruellia generally occurs as a weak stemmed herbaceous wildflower and rarely attains a height greater than 18 inches. Native ruellia is extremely adaptable in terms of growing conditions. I have seen it deep within shady hammocks in filtered sunlight and fully exposed in deep sand with turkey oaks and longleaf pine. It is one of the few wildflowers that will prosper in full sun to partial shade, and from well-drained sands to poorly drained loams. In all of these settings it will bloom and set seed, however, it will do best in the sunnier better drained locations. Ruellia blooms from early spring through early winter. The blossoms attract a variety of pollinators, but they are especially attractive to butterflies. Blooms generally disappear by Christmas and the plants become dormant until February. If you use ruellia in the home garden, you soon will discover that it spreads and fills any open area It does this by spreading slowly underground by suckers and by seed. The ripe seed capsules dry in the sun and explode with an audible "pop" by mid-morning, scattering the seeds far from the parent plant. Our native ruellia will never win an award for foliage beauty, but when it is used in mass it makes a very attractive addition to a wildflower garden and an excellent butterfly attractor.

Ruellia tweediana (syn. brittoniana), Mexican Petunia or Britton's wild petunia). This wildflower is not native, but a widely used landscape plant that originated from Mexico and has now become established statewide. Unlike our native ruellia, this wild petunia has dense foliage composed of narrow deep-green leaves. It also remains green and flowering throughout the winter and will become quite bushy if a winter freeze doesn't set it back. It shares many of the other characteristics with its cousin above. This is one reason why this plant frequently escapes and invades adjacent areas. Its seeds disperse far from the parent plants and will grow nearly everywhere. I do not recommend its use.

(Editor's Note: Mexican Petunia is now listed by the Florida Exotic Pest Plant Council as a Category I exotic pest plant.)

Other ruellias are sometimes offered in the landscape trade. Use caution in purchasing any of the non-natives unless you can easily confine them. Other natives occur in Florida too, but these are not found on our area.

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