Nota de aplicación
A large group of around 20,000 species of flowerless, seedless vascular plants having true roots from a rhizome and fronds that uncurl upward, reproducing by spores. The ferns are an ancient lineage of plants, dating back to at least the Devonian; during the Palaeozoic, tree-ferns grew several meters tall. The ferns include three living groups (Marattiales, Ophioglossales, and leptosporangiate ferns) and two or more extinct groups. An additional group, the Psilotales, is tentatively included in the ferns, although the group is vastly different from living ferns and its relationships are uncertain. The ferns group is also referred to as Polypodiophyta or Polypodiopsida when classified as a subdivision of tracheophyta (vascular plants).