Classification of pteridophyta

classification of pteridophytes

1. classification of pteridophyta

2. Classification of pteridophytes For a long time the division Pteridophyta included-the ferns, lycopods and horsetails. 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 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 4. Pteropsida . Classified into 4 divisions that have 40 families. They include about 10,000 living species (365 genera) distributed worldwide .

3. Classes of pteridophytes

4. Sub classes Division I Psilophyta Class 1. Psilotopsida Division II Lycophyta Class 1. Ligulopsida Class 2. E l igulopsida Division III Arthrophyta Class 1. Sphenophyllopsida Class 2. Calamopsida Division IV Filicophyta Class 1. Primofilicopsida Class 2. Eusporangiopsida Class 3. Protoleptosporangiopsida Class 4. Leptoprotosporangiopsida

5. 1. Psilophyta(Whisk ferns) Two genera (Psilotum and Tmesipteris) and 4-8 species • Most primitive • Rootless with rhizoids • Leaves often absent • Dichotomously branched photosynthetic stem • Protostele: is the condition where central core of xylem surrounded by phloem • Homosporous Synangium: trilocular structure that encloses sporangia • E.g. Fossil genera: Rhynia and Horneophyton • Living genera: Psilotum and Tmesipteris

6. 1. Psilophyta(Whisk ferns)

7. 2. Lycophyta (Club moss or spike moss) • Differentiated plant body • Microphyllous leaves • Protostele sometimes siphonostele • Sporophylls aggregate to form strobili or cones • Both homosporous and heterosporous. Lycopodium is homosporous whereas  Selaginella is heterosporous • Gametophyte depends on fungus for food

8. 2. Lycophyta (Club moss or spike moss)

9. 3. Sphenophyta (Horse tail) A single genus which have 35 species • All are fossils except Equisetum • Differentiated plant body • Stem joined with nodes and internodes • Scaly leaves seen as whorl around the node • Sporangia forming strobilus or cones • Homosporous

10. 3. Sphenophyta (Horse tail)

11. 4. Pterophya (Ferns or Filicophyta) • Most widely distributed vascular cryptogams • Differentiated plant body stem mostly rhizomatous • Leaves macro phyllous called as fronds • Young leaves show circinate vernation (spirally coiled) • Stele: protostele, siphonostele or dictyostele • Sporangia form sori on abaxial side of the leaf • Sporocarp in Marselia • Indusium may be true or false • Homosporous ( Pteris ) or heterosporous ( Marselia ) • Antherozoids multiflagellated

12. 4. Pterophya (Ferns or Filicophyta)