Submitted to: American Journal of Botany
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/1/2004
Publication Date: 8/22/2005
Citation: Woods, K., Hilu, K.W., Borsch, T., Wiersema, J.H. 2005. Pattern of variation and systematics of Nymphaea odorata: II. Sequence information from ITS and trnL-trnF. Systematic Botany 30:481-493. Interpretive Summary: Waterlilies are among the most beautiful aquatic plants cultivated by horticulturalists. They also exist in the wild throughout North America. Although studied for decades, there is still disagreement about whether there is one or two subspecies of the common waterlily in North America. With the use of molecular tools, it is possible to determine relationships among these plants. Sequence data from two regions of the genome of waterlilies were used to evaluate the two subspecies that are recognized within this waterlily. These data suggest that some gene flow or hybridization occurs between the two subspecies especially in places where the two subspecies grow together. In general, however, the two subspecies should still be recognized because they are genetically distinct in most places where they exist in nature. This research will be used by botanists to accurately describe and name the common waterlilies in North America.
Technical Abstract: Sequence data from the nuclear internal transcribed spacer (ITS) and the plastid trnL-trnF regions were used to assess relationships among populations of Nymphaea odorata across its North American range, and to evaluate if subsp. odorata and subsp. tuberosa form distinct taxonomic units. The trnT-F region provided a single informative site. In contrast, the ITS region was more variable, supporting the monophyly of the two species. Within N. odorata, two clades were resolved representing the two subspecies, whereas a few individuals appeared outside these two clades. Polymorphic sites were detected in ITS, indicating possible hybridization between the subspecies. The geographic location of these hybrids suggests a possible hybrid zone. Overall, molecular evidence supports the segregation of subsp. odorata and subsp. tuberosa, with limited gene flow between the subspecies.