Early life: Ancient lineages of vascular plants

Photo by A. Murray Evans

Most biologists are accustomed to thinking of ferns and horsetails as transitional evolutionary grades of 'lower plants' from which seed plants were eventually derived. A new phylogenetic analysis suggests that the ferns and horsetails are the closest living relatives of the seed plants, but have been an evolutionarily independent group or clade for much longer than was thought, probably since before many of the major features characteristic of vascular plants had developed. Viewing the horestail-ferns and seed plants as contemporaneous and ancient lineages will have implications for our understanding of how terrestrial ecosystems and landscapes evolved.

Horsetails and ferns are a monophyletic group and the closest living relatives to seed plants
KATHLEEN M. PRYER, HARALD SCHNEIDER, ALAN R. SMITH, RAYMOND CRANFILL, PAUL G. WOLF, JEFFREY S. HUNT, SEDONIA D. SIPES
Nature 409, 618-622 (1 February 2001)
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1 February 2001 table of contents