A fern is any one of a group of about 12,000 species of plants . Unlike
mosses they have xylem and phloem (making them vascular plants). They
have stems, leaves, and roots like other vascular plants. Ferns do not have
either seeds or flowers (they reproduce via spores).
By far the largest group of ferns are the leptosporangiate ferns, but ferns as
defined here (also called monilophytes) include horsetails, whisk ferns,
marattioid ferns, and ophioglossoid ferns. The term pteridophyte also refers
to ferns (and possibly other seedless vascular plants; see classification section
Ferns first appear in the fossil record in the Carboniferous but many of the
current families and species did not appear until roughly the late Cretaceous
(after flowering plants came to dominate many environments).
Ferns are not of major economic importance, but some are grown or
gathered for food, as ornamental plants, or for remediating contaminated
soils. Some are significant weeds. They also feature in mythology, medicine,