Eupolypods I is a clade of ferns in the order Polypodiales, class Polypodiopsida. It probably diverged from Eupolypods II during the mid-Cretaceous. The divergence is supported by both molecular data and an often overlooked morphological characteristic which lies in the vasculature of the petiole. Most species that make up the Eupolypods I clade have three vascular bundles. The only exceptions are the Grammitid ferns which have one, and the genus Hypodematium which has two. This differs from Eupolypods II which mostly have two vascular bundles (except the well-nested blechnoid ferns which generally have at least three).