They are important regions in the life of the modern man and have been treated for diverse authors (MANTOVANI, 1989; RODRIGUES, 1991; SOUZA, 1998; SOUZA, 1999; RASP and ZAKIA, 2004). Riprias forest formations constitute the forest covering that occurs throughout the water courses, in the riprio ectono. They possess high related importance, mainly, to the biodiversity and the maintenance of the balance of the aquatic ecosystem (SOUZA, 1999). However, its relation with the balance of the aquatic ecosystem has caused more impact, therefore it treats, amongst others, of questions on the quality of the water for the human consumption (RIZZI, 1963). Diverse studies have been developed with intention to delineate the florstica composition of the riprias forests (VAZZOLER et al., 1997) as flora survey (SOUZA et al., 1997; ROMAGNOLO et al., 1994; SOUZA, 1998; SOUZA and HUNTER, 2005), dynamics in the specific restoration of the forests (SOUZA, 1998; SOUZA et al.
2004a; 2004b), fissociologia of the forest remainders (SOUZA et al., 1997). Each time more, however, has been demonstrated the occurrence of low similarity between different areas. For the alagvel plain of the high river Paran, Souza et al. (2004b) they had verified the occurrence of only 2.8% of common species and exclusive 55,2% of only one of the nine remainders analyzed for fitossociolgicos methods. Rodrigueses and Nave (2000) had found resulted similar when analyzing 43 surveys carried through in extra-Amazonian Brazil.
The vegetation of the plain is composed for 652 species of fanergamas identified (to SOUZA et al.1997; SOUZA and KITA, 2002), sobressaindo the herbaceous ones. These colonize ample natural fields that dominate the landscape of the site. In these fields, the grassy ones predominate (Panicum prionitis, P. mertensii, P. maximum), cyperaceas (Cyperus digitatus, C. difusus) and amarantceas (Pfaffia glomerata). Pendula enters the more common arbustivas forms is Senna, Aeschynomene sp. Sapuim bigladulatum e, between the isolated arbreas, Inga uruguensis and urucurana Croton.