The stems of ferns are typically at or under the group so what appears to be an entire fern plant is actually just a leaf and what appears to be leaves are more accuralely called leaflets (which then may be subdivided into subleaflets). The earliest plants reproduced using spores, rather than seeds and ferns are the most common surviving seedless plants. In some ferns, the spores are located on the underside of leaflets. In other ferns, green leaves are sterile and all spores are located on brown, fertile leaves (often mistaken for dead leaves). Ferns actually have two parts of their life cycle, although the gametophyte stage is typically two small to be noticed.
--ferns with a tall naked leaf axis; all leaflets located at the top of the leaf, primarily in horizontal plane
--large ferns, more than three feet tall
--small ferns whose leaflets are entire or possess one single lobe near base --medium-sized ferns without a tall, naked leaf axis