Open Access

Elmar Emil Leppik

• Six clearly separable evolutionary levels in the floral evolution of the Ranunculaceae were found to coincide with the six corresponding stages of sensory development of their pollinators as follows: amorphic -> haplomorphic -> actinomorphic -> pleomorphic -> stereomorphic-zygomorphic. This is a basic trend of floral evolution, fully recapitulated in a single family. Except for the first (amorphic), all upper levels are represented in the present-day floras as clearly separable type-classes. They are therefore accessible to direct observations and experimental study. Extensive statistical data on flower visitors of the Ranunculaceae confirm the proposed theory of the mutual interrelationship between the evolutionary levels of flower types and sensory stages of pollinating insects. The new picture, obtained by this study, gives us a better understanding of the evolutionary relationship between insects and plants and explains the extreme diversity in the floral structure of the Ranunculaceae.