division Pteridophyta, Pteridophyta - containing all the vascular plants that do not bear seeds: ferns, horsetails, club mosses, and whisk ferns; in some classifications considered a subdivision of Tracheophyta

fern - any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores

fern ally - pteridophytes of other classes than Filicopsida

tracheophyte, vascular plant - green plant having a vascular system: ferns, gymnosperms, angiosperms