Sailing by Jaco Verheul

Ferns are a group of vascular plants, according to classification, belonging to the Pteropsida or to the Monilophyta. The ferns include not only the 'true ferns' but also the eusporangiate ferns (the 'fern-like ferns', English: fern allies) - including the horsetails, the Psilotopsida with the addertongue family, and the Marattiopsida, but excluding the Lycophyta (wolf claws and rush ferns).

Ferns have roots, which draw water from the soil or from the water, or they are absent. Most species have a rhizome (rhizome), a creeping piece of stem under the ground. There are also tree ferns that form a sham stem with the stems, giving a 'tree-like' appearance.

The ferns have leaves that spring from the rhizome. These are not readily comparable to the leaves of seed plants. Many species of ferns have not only fertile (fruitful) leaves, on which the sporangia are located, but also sterile (infertile) leaves without spores, e.g. double-leaf. In many other species, there is no distinction between fertile and sterile leaves, for example in kidney fern.

Like mosses and wolf claws, ferns multiply by means of spores and do not form seeds.

Ferns form very ancient plant groups, with fossils known from the mid-Devonian. In the Carboniferous, the group was very numerous and shapely. Although most of these species became extinct in the Permian, the group has always been emphatic; for a review of fossil ferns, see.

Ferns and ferns are found all over the world. There are thousands of different species. In particular, they are abundant in rain forests (tropical or temperate), because here one of the most important requirements for the fern's habitat - moisture - is guaranteed.