Although the relationship of angiosperms to other seed plants remains controversial1, great progress has been made in identifying the earliest extant splits in flowering-plant phylogeny, with the discovery that the New Caledonian shrub Amborella trichopoda, the water lilies (Nymphaeales), and the woody Austrobaileyales constitute a basal grade of lines that diverged before the main radiation in the clade2,3,4,5,6,7,8. By focusing attention on these ancient lines, this finding has re-written our understanding of angiosperm structural and reproductive biology, physiology, ecology and taxonomy9,10,11,12. The discovery of a new basal lineage would lead to further re-evaluation of the initial angiosperm radiation, but would also be unexpected, as nearly all of the ∼460 flowering-plant families have been surveyed in molecular studies10. Here we show that Hydatellaceae, a small family of dwarf aquatics that were formerly interpreted as monocots, are instead a highly modified and previously unrecognized ancient lineage of angiosperms. Molecular phylogenetic analyses of multiple plastid genes and associated noncoding regions from the two genera of Hydatellaceae identify this overlooked family as the sister group of Nymphaeales. This surprising result is further corroborated by evidence from the nuclear gene phytochrome C (PHYC), and by numerous morphological characters. This indicates that water lilies are part of a larger lineage that evolved more extreme and diverse modifications for life in an aquatic habitat than previously recognized.
Access optionsAccess options
Subscribe to Journal
Get full journal access for 1 year
only $3.90 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
We are grateful to K. Bremer (Uppsala University) and the Royal Botanic Gardens, Kew, for generously providing DNAs, and to J. Conran, J. Davis, A. Doust, P. Rudall and D. Stevenson and other workers responsible for making the field collections and generating cultivated material. We acknowledge critical review of the manuscript by S. C. H. Barrett, M. W. Chase, T. S. Feild and E. M. Friis. This research was supported by an NSERC Discovery Grant to S.W.G., NSERC postgraduate scholarships to J.M.S. and H.S.R., Alberta Ingenuity and University Graduate Fellowship (University of British Columbia) funding to J.M.S, an NSF grant to S.M, and Royal Botanic Gardens Trust Sydney funding to A.D.M. and B.G.B.
Author Contributions Plastid data were generated by J.M.S., H.S.R. and A.D.M.; nuclear data were generated by S.M.; morphological data were compiled and scored by J.A.D, P.K.E. and B.G.B. Analyses were conceived and performed by S.W.G, J.A.D., J.M.S., H.S.R and S.M. All authors contributed to the writing, which was coordinated by S.W.G. and J.A.D.
Novel sequences for this study have GenBank accession numbers as follows: Aphelia brizula (EF153935, EF153937, EF153939, EF153942, EF153945, EF153948, EF153950, EF153952, EF153954); Brasenia schreberi (DQ981792); Centrolepis monogyna (EF153934, EF153936, EF153938, EF153941, EF153944, EF153947, EF153949, EF153951, EF153953); Hydatella inconspicua (DQ916291); Trithuria submersa (AJ419142, DQ915185-DQ915189, DQ981794, EF153940, EF153943, EF153946); Schisandra sphenanthera (DQ981793). Alignments used are available for download in Supplementary Information
This file contains Supplementary Data 1 with Nexus file which is the main multigene plastid data set used to perform analyses summarized in Fig. 2 and Suppl. Fig. 1.
This file contains Supplementary Data 2 with Nexus file which is the PHYC data set used to perform analyses summarized in Fig. 3a and Suppl. Fig. 2.
This file contains Supplementary Data 3 with Nexus file which is the plastid trnTLF data set used to perform analyses summarized in Fig. 3b and Suppl. Fig. 3.
This file contains Supplementary Data 4 with Nexus file which is the morphology data set used to perform analyses summarized in Fig. 3c, Fig. 4 and Suppl. Fig. 4.
About this article
The Botanical Review (2012)