In message , adelaide
writes
http://imageshack.us/photo/my-images...082011611.jpg/

The plant is herbaceous, very very abundant. Its height is approximately 1
to 2 meters. Colonies of the plant are growing on the surface that was
flooded last year. The Rudbeckia genus was suspected, but this plant looks
diferent...
Greetings to everyone, hope for your sugestions.:-)

This newsgroup is not very active. You could try rec.gardens.

That said, from the photograph I couldn't even place it as a composite,
but assuming that it is, possibly a species of Bidens.
--
Stewart Robert Hinsley