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Horsetails and ferns are a monophyletic group and the closest living relatives to seed plants


Most of the 470-million-year history of plants on land belongs to bryophytes, pteridophytes and gymnosperms, which eventually yielded to the ecological dominance by angiosperms 90 Myr ago1,2,3. Our knowledge of angiosperm phylogeny, particularly the branching order of the earliest lineages, has recently been increased by the concurrence of multigene sequence analyses4,5,6. However, reconstructing relationships for all the main lineages of vascular plants that diverged since the Devonian period has remained a challenge. Here we report phylogenetic analyses of combined data—from morphology and from four genes—for 35 representatives from all the main lineages of land plants. We show that there are three monophyletic groups of extant vascular plants: (1) lycophytes, (2) seed plants and (3) a clade including equisetophytes (horsetails), psilotophytes (whisk ferns) and all eusporangiate and leptosporangiate ferns. Our maximum-likelihood analysis shows unambiguously that horsetails and ferns together are the closest relatives to seed plants. This refutes the prevailing view that horsetails and ferns are transitional evolutionary grades between bryophytes and seed plants7, and has important implications for our understanding of the development and evolution of plants8.

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Figure 1: Phylogenetic relationships for all the main lineages of vascular plants inferred from maximum-likelihood (ML) analysis of the combined chloroplast rbcL, atpB, rps4 and nuclear small-subunit rDNA data set.
Figure 2: A portion of the chloroplast rps4 alignment.


  1. Kenrick, P. & Crane, P. R. The Origin and Early Diversification of Land Plants: A Cladistic Study (Smithsonian Institution Press, Washington DC, 1997).

    Google Scholar 

  2. Kenrick, P. & Crane, P. R. The origin and early evolution of plants on land. Nature 389, 33–39 (1997).

    Article  ADS  CAS  Google Scholar 

  3. Lupia, R., Lidgard, S. & Crane, P. R. Comparing palynological abundance and diversity: Implications for biotic replacement during the Cretaceous angiosperm radiation. Paleobiology 25, 305–340 (1999).

    Article  Google Scholar 

  4. Soltis, P. S., Soltis, D. E. & Chase, M. W. Angiosperm phylogeny inferred from multiple genes as a tool for comparative biology. Nature 402, 402–404 (1999).

    Article  ADS  CAS  Google Scholar 

  5. Qiu, Y.-L. et al. The earliest angiosperms: Evidence from mitochondrial, plastid and nuclear genomes. Nature 402, 404–407 (1999).

    Article  ADS  CAS  Google Scholar 

  6. Barkman, T. J. et al. Independent and combined analyses of sequences from all three genomic compartments converge on the root of flowering plant phylogeny. Proc. Natl Acad. Sci. USA 97, 13166–13171 (2000).

    Article  ADS  CAS  Google Scholar 

  7. Rothwell, G. W. Fossils and ferns in the resolution of land plant phylogeny. Bot. Rev. 65, 188–218 (1999).

    Article  Google Scholar 

  8. Graham, L. E., Cook, M. E. & Busse, J. S. The origin of plants: Body plan changes contributing to a major evolutionary radiation. Proc. Natl Acad. Sci. USA 97, 4535–4540 (2000).

    Article  ADS  CAS  Google Scholar 

  9. Bremer, K. Summary of green plant phylogeny and classification. Cladistics 1, 369–385 (1985).

    Article  Google Scholar 

  10. Duff, R. J. & Nickrent, D. L. Phylogenetic relationships of land plants using mitochondrial small-subunit rDNA sequences. Am. J. Bot. 86, 372–386 (1999).

    Article  CAS  Google Scholar 

  11. Hedderson, T. A., Chapman, R. & Cox, C. J. in Bryology for the Twenty-first Century (eds Bates, J. W., Ashton, N. W. & Duckett, J. G.) 65–77 (Maney Publishing and the British Bryological Society, Leeds, 1998).

    Google Scholar 

  12. Mishler, B. D. et al. Phylogenetic relationships of the “green algae” and “bryophytes”. Ann. Missouri Bot. Gard. 81, 451–483 (1994).

    Article  Google Scholar 

  13. Qiu, Y.-L., Cho, Y., Cox, J. C. & Palmer, J. D. The gain of three mitochondrial introns identifies liverworts as the earliest land plants. Nature 394, 671–674 (1998).

    Article  ADS  CAS  Google Scholar 

  14. Hiesel, R., von Haeseler, A. & Brennicke, A. Plant mitochondrial nucleic acid sequences as a tool for phylogenetic analysis. Proc. Natl Acad. Sci. USA 91, 634–638 (1994).

    Article  ADS  CAS  Google Scholar 

  15. Kranz, H. D. & Huss, V. A. R. Molecular evolution of pteridophytes and their relationships to seed plants: Evidence from complete 18S rRNA gene sequences. Plant Syst. Evol. 202, 1–11 (1996).

    Article  CAS  Google Scholar 

  16. Raubeson, L. A. & Jansen, R. K. Chloroplast DNA evidence on the ancient evolutionary split in vascular land plants. Science 255, 1697–1699 (1992).

    Article  ADS  CAS  Google Scholar 

  17. Stevenson, D. W. & Loconte, H. in Pteridology in Perspective (eds Camus, J. M., Gibby, M. & Johns, R. J.) 435–467 (Royal Botanic Gardens, Kew, 1996).

    Google Scholar 

  18. Wagner, W. H. Jr Systematic implications of the Psilotaceae. Brittonia 29, 54–63 (1977).

    Article  Google Scholar 

  19. Manhart, J. R. Phylogenetic analysis of green plant rbcL sequences. Mol. Phylogenet. Evol. 3, 114–127 (1994).

    Article  CAS  Google Scholar 

  20. Pryer, K. M., Smith, A. R. & Skog, J. E. Phylogenetic relationships of extant ferns based on evidence from morphology and rbcL sequences. Am. Fern J. 85, 205–282 (1995).

    Article  Google Scholar 

  21. Sanderson, M. J., Wojciechowski, M. F., Hu, J. M., Sher Khan, T. & Brady, S. G. Error, bias, and long-branch attraction in data for two chloroplast photosystem genes in seed plants. Mol. Biol. Evol. 17, 782–797 (2000).

    Article  CAS  Google Scholar 

  22. Hillis, D. M. Inferring complex phylogenies. Nature 383, 130–131 (1996).

    Article  ADS  CAS  Google Scholar 

  23. Bowe, L. M., Coat, G. & dePamphilis, C. W. Phylogeny of seed plants based on all three genomic compartments: Extant gymnosperms are monophyletic and Gnetales' closest relatives are conifers. Proc. Natl Acad. Sci. USA 97, 4092–4097 (2000).

    Article  ADS  CAS  Google Scholar 

  24. Chaw, S.-M., Parkinson, C. L., Cheng, Y., Vincent, T. M. & Palmer, J. D. Seed plant phylogeny inferred from all three plant genomes: Monophyly of extant gymnosperms and origin of Gnetales from conifers. Proc. Natl Acad. Sci. USA 97, 4086–4091 (2000).

    Article  ADS  CAS  Google Scholar 

  25. Lewis, P. O. in Molecular Systematics of Plants II; DNA Sequencing (eds Soltis, D. E., Soltis, P. S. & Doyle, J. J.) 132–163 (Kluwer Academic, Boston, 1998).

    Book  Google Scholar 

  26. Renzaglia, K. S., Duff, R. J., Nickrent, D. L. & Garbary, D. J. Vegetative and reproductive innovations of early land plants: Implications for a unified phylogeny. Phil. Trans. R. Soc. Lond. B 355, 769–793 (2000).

    Article  CAS  Google Scholar 

  27. Adoutte, A. et al. The new animal phylogeny: Reliability and implications. Proc. Natl Acad. Sci. USA 97, 4453–4456 (2000).

    Article  ADS  CAS  Google Scholar 

  28. Theissen, G. et al. A short history of MADS-box genes in plants. Plant Mol. Biol. 42, 115–149 (2000).

    Article  CAS  Google Scholar 

  29. Hickok, L. G., Warne, T. R. & Fribourg, R. S. The biology of the fern Ceratopteris and its use as a model system. Int. J. Plant Sci. 156, 332–345 (1995).

    Article  Google Scholar 

  30. Swofford, D. L. PAUP*. Phylogenetic Analysis Using Parsimony (*and other Methods) (Sinauer, Sunderland, Massachusetts, 1999).

    Google Scholar 

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We thank R. Lupia, F. M. Lutzoni, B. D. Mishler, L. Newstrom-Lloyd and S. Zoller for critical comments on the manuscript; Z. Dabich, J. Bélisle, R. Lupia and D. Kieffer for assistance in rendering Fig. 1; F. M. Lutzoni and V. A. Funk for advice on phylogenetic analyses; I. Capesius, S. Boyles, B. Goffinet, M. Hasebe, M. Kato, M. Kessler, B. D. Mishler, R. Moran, J. Shaw, W. C. Taylor, Y.-L. Qiu, D. Wall, J. Wheeler, and greenhouse managers at Humboldt State University, University of California at Davis, University of California Botanical Garden at Berkeley, New York Botanical Garden for plant material; S. W. Graham, P. S. Soltis and J. Therrien for sharing unpublished sequence data; and D. Ferguson, E. Grismer, J. Irwin and L. Sappelsa for general assistance in the initial stages of the project. This work was supported by grants from the NSF to K.M.P., A.R.S., P.G.W. and R. C., the Green Plant Phylogeny Research Coordination Group (USDA grant), and by the Pritzker Foundation Fund of The Field Museum.

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Correspondence to Kathleen M. Pryer.

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Pryer, K., Schneider, H., Smith, A. et al. Horsetails and ferns are a monophyletic group and the closest living relatives to seed plants. Nature 409, 618–622 (2001).

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