Trees and bushes aside, Ruellia nudiflora (common wild petunia) is probably the unofficial wildflower of Brownsville. It is just about everywhere. Unfortunately, we don't have bluebonnets in this part of South Texas.
It's not all paradise in tropical Texas in the Rio Grande Valley. True, we are blessed with amazing weather, barring the occassional blast of artic air in the winter. Thanks to the warm weather, we can grow an amazing array of plants, but we have to overcome shortfalls in our soil (high levels of salt and low levels of iron) and moderate amount of rain (26-27 inches).