Hmmm, no such thing as semi-invasive. That's sort of like being semi-pregnant.
Regarding Mexican Petunias, you probably have Ruellia brittoniana but Strobilanthes atropurpureus is a possibility. Both are native to Mexico. Both can reproduce when plant parts touch the ground which root and grow eventually producing large colonies of plants. They also spread by rhizomes. The next issue is the seed. Mexican Petunias flower in spring, summer, and fall down in your neck of the woods. That means they are producing seed for about 9 months out of the year under ideal conditions. Given what prolific seeders they are and given there is documentation out there that the seed from a single plant is capable of literally traveling miles... can you be so sure it will land in an inhospitable environment? Basically, these plants reproduce both vegetatively and sexually. That can be a big problem. Deadheading them can reduce the spread but it is often difficult to keep up with that and then there are the rhizomes with which to contend.
There is a reason why Mexican Petunia is listed as a Category I invasive species by the Florida Exotic Pest Plant Council. It is "altering native plant communities by displacing native species, changing community structures or ecological functions, or hybridizing with natives". This warning applies to all parts of the state of Florida (and other areas with similar mild climates). Where hardy, the Mexican petunia excels at invading wetlands.
Here's a link from your own state so you can read up on what you have planted in your yard-
http://www.bonus.com/contour....ri.html
Tre, that's a highly invasive species and a prescribed burn would be ineffective as it isn't going to be able to control them. Well, it may help a tad on your property.
I think you might want to consider joining a local native plant society. I believe you will find the vast majority meet in the evening to accommodate those who work. There is a link at this site to find a local chapter-
http://www.fnps.org/
Regarding using Mexican Petunias for erosion control, who told you this? Did you read it on line somewhere? Possibly in a book or in a pamphlet from a nursery selling Mexican Petunias? There are much better plants for watershed management and erosion control. The Mexican Petunia isn't one of them as to the best of my knowledge it is rather ineffective/counter productive for a multitude of reasons. Try contacting these people for a list of species that will really work for you-
http://www.fnps.org/pages/plants/invasives.php
Also, Florida has established a farmers' native seed co-op called the Florida Wildflower Cooperative. You might want to contact them for seed. You can read a little bit about it here-
http://stormwatercenter.com/ecm_0411_trends.html
Forget purchasing a book for right now. You can save your $30 and start right here-
http://edis.ifas.ufl.edu/EP011#TABLE_1
That's a decent wild plant guide and you can look up images of the species your are interested in right on the Internet.
In order to properly ID your plants, you need to have good photos. There are people at those native plant societies who can spot a non native a mile away. Just remember that the vast majority of non natives are very well behaved (something some native plant lovers don’t like to admit) so don't go ripping anything out of your yard until you know what you have. Non native plant people can be a little bit overzealous. Anyway, once you find out the Latin name to your plant, type it in to your browser and add the word invasive. Make sure your spelling is correct. You should be able to find the answer to your questions real quick.
Best wishes to you.
