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Recent progress in clarifying relationships among the major groups of monocots has facilitated our understanding of morphological evolution. Morphological misfits are taxa whose phenotype is anomalous in the context of their phylogenetic placement and often does not fit readily into the conceptual framework of classical morphology. This paper focuses on reproductive structures in the order Pandanales. In some genera of Pandanales, notably Cyclanthus, Lacandonia, and Sararanga, interpretation of the boundaries of individual flowers is problematic. The flowers of Lacandonia are almost unique among extant angiosperms in that they are "inside-out," with the carpels surrounding the stamens. These structures have been variously interpreted as either flowers or inflorescences, perhaps as an example of fasciation caused by changes in the reproductive apex. This paper revisits this debate in the context of recent phylogenetic data on monocots. It explores whether such anomalous taxa have a predictive value in highlighting significant developmental constraints, or limitations on phenotypic variability that can help to explain why evolution is apparently canalized in different lineages. An ultimate goal is to develop hypotheses of monocot evolution that are potentially testable using developmental genetics.
