In the Florida area alone, there are about 24 genera and 100 species of this remarkable plant. Ferns vary greatly, ranging from small specimens less than a centimeter, to giant ferns found in the tropical rainforests. These plants are represented not only in the tropics, but also in temperate forests. To see some uses of ferns, look at Ferns of New Guinea . The frond, or leaf, consists of the blade and the petiole, which attaches the leaf to the stem.
Pinnae are the feathery segments, or leaflets, into which the frond is divided.
Rhizomes are horizontal stems that grow underground. Roots anchor the plant to its substrate and help it obtain nutrients. The stems of some ferns are covered with suberin, a fatty substance which makes the epidermal cells look tough and barklike. The vascular tissue of the stem and roots have a siphonostele arrangement. I want to go back to the beginning An Evolution of the Taxon Ferns arose in the Devonian period and adaptively radiated into various new species along with other tracheophytes, in the Carbinoferous period, all during the Paleozoic era.