BOT 360F - Families of Vascular Plants



Nymphaea odorata

Photo M. Ferguson © 2001 Royal Ontario Museum (TRT 8783)

Nymphaeaceae (at left, the Ontario species Nymphaea odorata) and the closely related Cabombaceae form the second lowest branch on the 5-gene angiosperm tree of Qiu et al. (1999). In Nymphaea the many petals and stamens are arranged in a continuous spiral. The gynoecium comprises 10-20 subunits, sunk into receptacle, and matures as a many-seeded berry. The seeds are dispersed by water, kept afloat by their spongy aril and the air bubbles that it entraps. When the aril decays, the seeds sink and germinate to give rise to the rhizome or tuber from which the floating leaves and flowers arise.

Judd et al. (1999: 168-169; Fig. 8.9) give presumed synapomorphies for the family in boldface. These features are quite unlike those that separate other families, leading Mabberley (1997) to observe that if the Nymphaeaceae had been the first angiosperms studied in detail then our classification of flowering plants probably would have been quite different. Conversely, genera within the Nymphaceae differ from each other in features that in other plants would distinguish families or groups of families (e.g. ovary position, presence of a corolla, stamen and ovule morphology, vascular bundles scattered or in a ring, chemical features).

"Primitive" features of the family include pollen morphology and beetle pollination, whereas the aquatic habitat and the lack of vessels may be considered specialized or advanced features.


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