The original version of this Article contained an error in Fig. 5, in which the evolutionary origin of DRM2 was incorrectly placed prior to the divergence between gymnosperms and angiosperms. The correct evolutionary origin of DRM2 should be in angiosperms. In addition, in the “Percent methylation change” section of the Methods, Equation 1 was incorrect. This has been corrected in both the PDF and HTML versions of the Article. An amendment to this paper has been published and can be accessed via a link at the top of the paper.