Jan Scholten

English: Ferns.
Botany: Ferns, Horsetails and Clubmosses; vascular; spore plants; having xylem and phloem, vessels; vascular plants; having stems, leaves, roots; reproduce via spores; have neither seeds nor flowers.

Pteridophyta is a phylum in the Plant kingdom, including the Ferns, Horsetails and Clubmosses. It is the first clade in the Tracheophyta, the vascular plants. They are spore plants and have no flowers or seeds. Pteridophyta are divided in Lycophyta or Lycopodiophyta and Monilophyta. Lycopodiophyta are sometimes placed outside of Pteridophyta. Lycopodiophyta and Pteridophyta are then classified as the two living clades at the start of the Tracheophyta. Tracheophyta is the clade that also comprises Gymnospermae and Angiospermae.
Extinct clades of the extended Pteridophyta are Rhyniophyta, Zosterophyllophyta, Trimerophytophyta and Progymnospermophyta.
In the Plant theory Pteridophyta, including Lycopodiophyta, are placed in the Phylum 4, having the connection with the Iron series. They are subdivided in the following Classes.
The Pteridophyta are difficult to classify. This is due to lack of homeopathic information in the form of Materia Medica and cases. It is due to the fact that many Orders are small, including only one family and that many Families are small, including only 1 or a few genera. This is partly a reflection of the fact that many species have since long become extinct.

1. Hydrogen series: Rhiniophyta?
2. Carbon series: Lycopodiidae, Lycophyta, Clubmosses.
3. Silicon series: Equisetidae, Equisetophyta, Eusporangiate ferns: Horsetails, Psilotales, Marattiales.
3. Iron series: Polypodiidae; Leptosporangiate ferns, Polypodiopsida; Pteridopsida, Ferns.

Content: thiaminase; tannins; flavonoids.