Ferns
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Fern, any of several nonflowering vascular plants
that possess true roots, stems, and complex leaves and that reproduce by
spores. They belong to the lower vascular plant division Pteridophyta, having
leaves usually with branching vein systems; the young leaves usually unroll
from a tight fiddlehead, or crozier. The number of fern species is about 9,000,
but estimates have ranged to as high as 15,000, the number varying because
certain groups are as yet poorly studied and because new species are still
being found in unexplored tropical areas. The ferns constitute an ancient
division of vascular plants, some of them as old as the carbonious fern
(beginning about 359 million years ago) and perhaps older. Their type of life
cycle, dependent upon spores for dispersal, long preceded the
Seed-plant life cycle. Another informal name for the
group, monilophytes, has gained currency in modern botanical literature.
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