As I am prone to, I shall offer another view on a story I read here first. I'll skip any further reference to the water hyacinth, as reported on by Tara, and just call a spade a spade. The damn things are water lilies, and nothing more or less than a pain in the ***, and originally a product of some well meaning world traveller who spied them in a river in Asia or South America (depending on which story you believe), and thought they would be a "pretty" addition to some unnamed stream in Florida, Louisiana, or Texas.  Bottom line: as usual, it is not nice to mess with mother nature. Story I got from my dad, was that after the water hyacinth was introduced, and proceeded to do what it does, which is to multiply exponentially and choke local streams, some "expert" in his moment of brlliance, deduced that the logical next step, was to import nutria, which are rumored to eat the damn water lilies..........well one brilliant screw-up begat another, and now we have swamps from Tivoli to Tallahassee, choked with "pretty" weeds, and oversized rats that are edible, low in cholesterol, and allegedly prized for their fur, that nobody wants any part of. Again, it would have been better had both scourges been left in their homeland, but it appears that they are here to stay. I say forget the herbicides, just rake 'em up and let them die in the sun. As far as the rats go......they were here before us, and just like cockroaches, they'll be here after we humans have cycled through our existence on planet earth, or the next big fireball from space plops down in Little Rock, causing a nuclear winter that lasts for eons.