Three non-native species of large constrictor snakes are now breeding in Florida, and several others have been encountered but have not yet established wild populations. This quick reference guide to identification of the native snakes you might easily mistake for introduced constrictors in Florida was written by Steve A. Johnson and Monica E. McGarrity, and published by the UF Department of Wildlife Ecology and Conservation, Januar 2011.
http://edis.ifas.ufl.edu/uw350