ferns

Kingdom: Plantae 

     Phylum: Streptophyta (Charophyte green algae & all land plants)

          Class: Equisetopsida (spore-bearing vascular plants)

     All ferns are vascular plants that reproduce via spores rather than seeds.  Spores are cells that can form a new individual without fusing to another reproductive cell.  Ferns are believed to have been among the first vascular plants that evolved to live on land.  Their life cycle includes a short gametophyte stage and a longer sporophyte stage.  This is in contrast to the first land plants, the Bryophytes, which have a long gametophyte stage and a transient sporophyte stage in the life cycle.  Ferns puzzled early botanists who couldn't understand how they could reproduce without seed or flowers.  Wilhelm Hofmeister is credited with discovering that ferns reproduced via spores.  

Ferns are further categorized based on their Subclass, Order, Family, Genus and Species.  

Ferns are the second most diverse group of vascular plants on earth, comprising 3 subclasses, 4 orders, >48 families, >319 genera and >12,000 species.  Many ferns are tropical.  However, ferns have adapted to every continent on earth except for Antartica.

    If Earth's 4.55-billion-year history is compressed into a 24-hour period, the first fossil records of ferns date to about 10:06 PM during the Devonian period.  However, most living ferns today belong to the Order Polypodiales, which developed during the early Cretaceous period around 11:20 pm on the 24-hour clock.  Our human ancestors don't appear until the last minute of this 24-hour Earth history day.

The American Fern Society has an excellent page About Ferns