Cayenne porterweed, Stachytarpheta cayennensis

This is porterweed because the decoction resembles porter style beer in color and texture. Not in results, which are more medicinal. Porterweed has long been used in attempts to treat a range of ailments. Authorities vary on whether this is a tropical American spread elsewhere, or if it is originally from south Asia. The American bunch are probably correct. In any case it is now aggressively pan-tropical. The only US location cited is Miami-Dade Co FL, but this shot is from Key Largo in Monroe Co. FL, 3/21/16.