Mycorrhizal evolution.

Two recent studies have cast new light on the evolutionary history of MYCORRHIZAE. New fossil evidence has pushed the date for the appearance of ARBUSCULAR MYCORRHIZAE back to 460 million years ago, predating vascular plants. A phylogenetic tree for the Basidiomycota shows that these fungi have gained (and lost) the ectomycorrhizal condition repeatedly during their history. These studies help highlight the paleoecological importance of mycorrhizae and add to our understanding of the evolution of mutualisms.