Analyses of genetic material from a multitude of fern species suggest that much of that plant group branched out millions of years after flowering plants appeared, a notion that contradicts many scientists' views of plant evolution.
Botanists estimate that ferns include more than 10,000 living species. Most modern ferns belong to a set of species called the leptosporangiates, which emerged at least 250 million years ago, says Kathleen M. Pryer of Duke University in Durham, N.C. Ferns dominated many ancient landscapes for more than 150 million years.
The fossil record suggests that the diversity and abundance of ferns sharply declined in the Cretaceous period, which began about 145 million years ago. The fos