Shoot and compound leaf comparisons in eudicots: dynamic morphology as an alternative approach

Recent developmental studies suggest that the compound leaf is a more or less incompletely developed shoot. Instead of considering leaves and shoots as non - homologous, this interpretation draws a continuum between leaves and shoots. This study considers the plant as a hierarchical series of units on which similar developmental processes are at work, and where each level (shoot, compound leaf, leaflet) is 'repeated' by the next higher level. Measurements related to the expression of developmental processes operating on leaves at the shoot level and on leaflets at the compound leaf level were used to determine if similar processes are at work at these different levels during early stages of organogenesis. Plants with compound leaves showing acropetal leaflet inception, representing a total 16 species from 10 eudicot families, were studied. Based on several types of quantitative analyses, there appears to be a continuum between so-called leaflets, compound leaves, and shoots in the species studied. This perspective, qualified as dynamic morphology, parallels the classical interpretation and is an alternative to it.