Native Plants

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Sunday - June 15, 2008

From: Austin, TX
Region: Southwest
Topic: Invasive Plants
Title: Invasiveness of wild petunia in Austin
Answered by: Barbara Medford

QUESTION:

Is the wild petunia in the data base as invasive/aggressive as the more common ruellia? In other words, will it pop up everywhere? Ruellia nudiflora (Engelm. & Gray) Urban Common wild petunia, Violet ruellia, Violet wild petunia, Wild petunia

ANSWER:

There are four members of the genus Ruellia that are native to Texas: Ruellia nudiflora (violet wild petunia), Ruellia drummondiana (Drummond's wild petunia), Ruellia humilis (fringeleaf wild petunia). and Ruellia occidentalis (western wild petunia). All are considered Plantwise native alternatives to non-native Ruellia caerulea (Britton's wild petunia), also known as Ruellia x brittoniana "Katie", which is widely available commercially. Ruellia caerulea is on the Texas Invasives list, but whether it is more or less invasive than the natives is a little hard to say. They all seed prolifically, grow well in shady, moist areas, and grow fairly quickly in the warm season. However, information in our Native Plant Database indicates that the Ruellias can be kept under control by mowing. They are all difficult to pull up, because they have a large knot in the root just below the surface of the soil. Many gardeners pick the non-native caerulea because it has been hybridized or selected to provide other colors than the native purple; pink, white and blue, although purple has remained the most popular color. Perhaps the main point in favor of using the natives is that they ARE natives, accustomed to living in their environment, requiring less fertilizer, water and maintenance to do well.

Pictures of non-native Ruellia caerulea

Ruellia nudiflora

Ruellia drummondiana

Ruellia humilis