XVI International Botanical Congess

The usual interpretation, to explain the organography of this aquatic floating heterosporous fern-three leaves at each node, two floating and a submerged root-like types-and the other viewpoint-the submerged leaf is a lateral branch-are discussed. Another recent interpretation, which sound interesting, as a result says that Salvinia is an anisophyllous fern, possessing at each node, two floating entire leaves +a submerged compound one. Framing this idea into the topographical homology-as a method-and homophyly-as a theory upon fossil evidence-the whole complex could be interpreted as a compound leaf with two (+) and (-) subopposite floating pinnae ending in three or more root-like pinnae, which could be fertile, as an example, of hemidimorphism, not anisophyllia. Also, this situation supports the occurrence of the rotated-lamina syndrome in this fern-genus.