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Classification of Cryptogams

Traditionally the Cryptogams are grouped into Thallophyte, Bryophyte and Pteridophyte. 

 

  • Thallophyte includes algae, fungi, etc. 

  • The Bryophytes include liverworts, hornworts and mosses.

  • Pteridophytes include ferns and their allies.

 

Division of Cryptogams

Thallophyta:

 

  • Thallophyte is any group of plants or plantlike organisms (such as algae and fungi) that lack differentiated stems, leaves, and roots. ‘Thallos’ means undifferentiated in Greek, and ‘phyton’ means plant.

  • Algae regenerate by sexual reproduction, involving male and female gametes (sex cells), by asexual reproduction, or by both ways. 

    • Asexual reproduction is the production of progeny without the union of cells or nuclear material. 

    • Many small algae reproduce asexually by ordinary cell division or by fragmentation, whereas larger algae reproduce by spores. 

  • Fungi reproduce sexually and/or asexually. Perfect fungi reproduce both sexually and asexually, while imperfect fungi reproduce only asexually (by mitosis). 

    • In both sexual and asexual reproduction, fungi produce spores that disperse from the parent organism by either floating on the wind or hitching a ride on an animal. 

    • Fungal spores are smaller and lighter than plant seeds.

 

Bryophyta

  • The word bryophyte is the collective term for mosses, hornworts and liverworts and bryology is the study of bryophytes.
  • In a moss plant one can find leaves growing from stems and in many moss species one will at times see solid-stalked spore capsules growing out from the leafy part of the plant. In other species the spore capsule will be stalkless. 
  • Hornworts are not leafy. The main part of the plant consists of a greenish, flattish sheet – which may be lobed or somewhat wrinkled. This sheet-like form is called a thallose growth habit. 
    • In hornworts the spore capsules are thin, tapering “horns” or needles that grow out from the thallose part. 
  • Bryophytes may reproduce both sexually and asexually. Bryophytes have neither pollen nor flowers and rely on water to carry the male sperm to the female eggs. 
    • The spore capsules are produced after a male gamete (the sperm) has fertilized a female gamete (the egg). Hence the spores are part of the sexual reproductive cycle. 
    • In the majority of the bryophytes spore dispersal is by wind.

 

Pteridophyte

  • Pteridophytes are ancient plants commonly referred to as ferns or fern allies. 
    • About 9% world Pteridophytes occur in India or only in 2.5% landmass of  the world.  
    • Ferns and Fern-allies are the second largest group of plants in Indian flora. 
  • Pteridophytes are first land vascular plants, so they are mostly terrestrial in nature, and grow in cool and shady places. Some pteridophytes are inhabited in xerophytic, semi-aquatic and aquatic conditions.
  • The Pteridophytes are an assemblage of flowerless, seedless, spore bearing vascular plants.
  • Reproduction through spores is the main mode of reproduction in Pteridophytes. Although vegetative reproduction is also common in pteridophytes.
  • Pteridophytes are economically very important. About 170 species of Pteridophytes have been found to be used as food, flavor, dyes, medicines, biofertilizers, oil, fibers and biogas production.

 

Conclusion

Though, most of the day to day basic needs of human beings are fulfilled from flowering plants, the value of cryptogams towards human civilization cannot be pretermitted. Cryptogams are the building blocks of every kind of ecosystem on the earth and an inherent part of biodiversity. They provide the suitable atmosphere for the growth of higher plants, insects and animals, and play a pivotal role in ecosystem services such as climate regulation, environmental monitoring, water purification, nutrient cycling, modification of habitat, etc. Even though many cryptogams are socio-economically important and are used for various purposes like food, fodder, vegetable, bio-fertilizer, folk medicines, agriculture, horticulture, different industries, etc. Botanical Survey of India (BSI) houses about 1700 Type specimens of different groups of Cryptogams.