The term Pteridophyta was first coined by Haeckel. Eichler (1883) divided the plant kingdom into Cryptogamia and Phanerogamia. The Cryptogamia was further divided into Thallophyta. Bryophyta and Pteridophyta. Engler (1909) included the Bryophyta and Pteridophyta under Embryophyta.
Due to discovery of the fossil plants, the classification of Pteridophytes has undergone vast changes in the recent past. Older taxonomists divided the vascular plants in two divisions—Pteridophyta (primitive vascular plants with absence of seeds) and spermatophyta (presence of seeds).
However, this distinction became invalid due to the discovery of seed bearing fossil plants (Cycadofilicales). Sinnott (1935), therefore, introduced a new term Tracheophyta for a division which possess sporophyte with a well-developed vascular tissue.
According to recommendations of I.C.B.N. (1952), the name of the division should end in the suffix-phyta, of a sub-division in-phytina and a class in -opsida.
On this basis Wardlaw (1955) divided the Pteridophytes into four divisions:
On the basis of their anatomy Jeffrey in 1902 divided the vascular plants into two types or ‘stocks’. He included ferns, gymnosperms and angiosperms in a ‘stock’ known as Pteropsida, and lycopods and horsetails in another ‘stock’ known as Lycopsida.
Scott in 1923 ranked them as divisions. He segregated the horsetails as a separate division, the Sphenopsida.
According to Eames (1936), Tippo (1942) and others there is a single division, the Trachaeophyta consisting of four subdivisions-1. Psilopsida, 2. Lycopsida, 3. Sphenopsida and 4. Pteropsida.
In 1950, the International Code of Botanical Nomenclature amended and recommended that all names of divisions end in the suffix-phyta and that of sub-divisions end in the suffix opsida.
According to Smith (1955) the classification of the pteridophytes is as follows:
Division I Psilophyta
Division II Lepidophyta
Division III Calamophyta
Division IV Pterophyta
In the so called modern system of classification by Fuller and Tippo (1954), pteridophytes are included in the phylum Tracheophyta which is divided into four sub-phylum.
- Pteropsida; it includes 3 classes: Gymnospermae, Angiospermae and Filicinae (fern).
The pteridophytes in the older systems are therefore restricted upto the subphylum Psiolpsida, Lycopsida, Sphenopsida and a class Filicinae of the subphyllum Pteropsida in the modern classification.