Haptanthus, Nelumbo
Morphological Anomalies: Haptanthus and Nelumbo
Transverse section through one half of flower, showing anthers adnate to tepal
Haptanthus: Haptanthus is a genus that has been collected only once, from beside a logging trail in Honduras. Numerous later expeditions, including one sponsored by National Geographic, have failed to re-collect it, making it likely that it is now extinct. It has a bizarre collection of morphological characters, including an inflorescence of spirally arranged lateral male flowers and a terminal carpellate flower that is somewhat similar to some Buxaceae. One of the most interesting questions is the nature of the staminate flowers, having been originally described as a single stamen with latrorse dehiscence. We have examined the single herbarium accession and have been allowed to remove two flowers for histological analysis. In contrast to earlier reports, we find that the structures of the staminate flower can be interpreted as either tepals with adnate bilocular introrse stamens or as foliose introrse stamens, either interpretation being unlike conventional floral structures. Without the benefit of molecular data (which we have attempted but failed to get from the very limited and degraded material available), we conclude that Haptanthus belongs in the basal eudicots, perhaps near Buxaceae.
Nelumbo: The reported arrangements of leaves, branches and flowers in Nelumbo is unique amongst angiosperms in having all structures initiate and grow from one side of the main axis. We are studying the morphology and development of both seedling and mature Nelumbo axes using scanning electron microscopy, histology, and expression of the meristem marker gene, knotted1.
Collaborator: Peter Stevens, University of Missouri-St. Louis and Missouri Botanic Gardens