A fern is a member of a group of about 10,560 known extant species of vascular plants that reproduce via spores and have neither seeds nor flowers. They differ from mosses by being vascular, i.e., having certain tissue that conducts water and nutrients. They have branched stems and leaves like other vascular plants. These are “megaphylls”, which are more complex than the simple “microphylls” of clubmosses. Most ferns are Leptosporangiate ferns, sometimes denominated the “true ferns”: they produce what are called “fiddleheads” that uncoil and expand into fronds. (source)