MEXICAN PETUNIA: According to Florida Exotic Pest Plant Council, Ruellia tweediana, Ruellia brittoniana, Ruellia coerulea and Ruellia malacosperma are all names for the same culprit. A Category I invasive plant is found doing some or all of the following:

� altering native plant communities by displacing native species

� changing community structures or ecological functions

� hybridizing with natives

Ironically, although it prefers wetlands, it's highly drought tolerant once established. And get this: the seeds have no dormancy mechanisms, they are ready to germinate almost immediately after leaving their little fruit capsules. No need for cold-treatment, scarification or stratification. Germination occurs over a broad range of temperatures, with or without light.

Florida is not the only state that is regretting its existence, either. Mexican petunia has established itself in nine states from South Carolina to Texas, and is marginally hardy through Zone 7. The FLEPPC Database reports presence of Ruellia t. in five different Floridian community types: pine flatwoods, hardwoods, (hammocks, tree islands) freshwater marshes, river banks, springs, and salt marshes.

Wildflower expert Carl Terwilliger found entire fields near the town of Clewiston completely overtaken by Ruellia t. over 20 years ago, and has seen it recently right in the Fakahatchee Strand. Further north, please see evidence pictured in link, as it invades Paynes Prairie Preserve State Park, and forms a complete monoculture-groundcover under the tress there: http://edis.ifas.ufl.edu/ep415.

And here�s a corker. Elastic energy stored in the seed capsules becomes converted to kinetic energy, or movement when the seams of the two halves of the capsule dry out; and when that happens, POP goes the petunia seed. This means seeds can be virtually sprayed out for distances up to ten feet from the mother plant. Add to this the fact that the plant forms dense colonies from horizontal stems both above and below ground...and you have rampant roots shoving the plants in clumps outward with seeds being sprayed all along the front lines as it proceeds.

Plus mucous. The little kinetically loaded seeds come pre-packaged with a mucous gel coat that forms when the seed becomes wet. Now it is capable of floating in water, and also will become glued to the soil when it lands there.

You will not be surprised to learn that Mexican petunia is extremely difficult to get rid of. The underground stems are nearly impossible to remove completely, and the seeds persist in the soil for years.