Variation of leaf morphology in Papaveraceae s.l. (including Fumariaceae and Pteridophyllum) has previously been shown to be related to developmental differences in the direction of segmentation and in blade-petiole differentiation. Based on ontogenetic comparisons, we here distinguish polyternate, acropetal, basipetal-pedate, basipetal-pinnate, and divergent modes of dissection. In addition, undissected leaves occur in some taxa. Dissection modes can be grouped in two classes on the basis of blade-petiole differentiation. Mapping of these morphogenetic traits on an independently obtained phylogenetic reconstruction reveals a high degree of homoplasy, indicating multiple evolutionary parallelisms and/or reversals. At the same time, considerable character fixation can also be observed in some clades. Although a variety of evolutionary scenarios are equally parsimonious, we propose that polyternate/acropetal/basipetal-pedate (PABpe class) leaves constitute the plesiomorphic state for Papaveraceae s.l. Evolutionary transformations between acropetal and basipetal segmentation modes might have been achieved by a change in the temporal coordination of segmentation competence versus acrotonic and basitonic growth phases.
