Four different types of male flowers exist. On the basis of these flower types, the genus has often been split into four genera—a more narrowly defined "Attalea", "Orbignya", "Maximiliana", and "Scheelea". The species sometimes referred to "Orbignya" have coiled anthers, while the other groups have straight ones. The petals of those placed in "Maximiliana" are much shorter than the stamens, while those placed in "Scheelea" and a more narrowly defined "Attalea" have petals that are longer than the stamens. Five species do not fit easily into any of these groups; this fact has been used as an argument in favour of considering this group a single genus.