CRUSTOSE LICHENS

STUDY OF EXTERNAL FEATURES OF CRUSTOSE LICHENS

Comments :-

  • The crustose lichens are hard, granular crusts on rocks and bark of the trees.
  • These adhere very closely and firmly to the substratum.
  • The thalli are partially or completely embedded in the substratum. 
  • These lichens are generally ash-coloured. However, the colours may vary.
  • The surface of the thallus is generally divided into polygonal areas called areolae.
  • Some of the commonest examples include Lecidea, Graphis, Lecanora.

CRUSTOSE LICHENS


CRUSTOSE LICHENS

STUDY OF INTERNAL STRUCTURE​ OF CRUSTOSE LICHENS

Comments :-

  • The thallus is poorly differentiated. 
  • The tissues forming the thallus are arranged more of less in strata, one above the other. 
  • The upper cortex is made of rudimentary or sometimes highly developed hyphal layer.
  • Algal layer lies just beneath this layer. The layer shows agal filaments and the fungal hyphae in close association. 
  • Much below the algal layer lies the medulla composed of loose tissue of branching hyphae. 
  • The lower cortex lies next to medulla. It may be well developed or entirely absent.

CRUSTOSE LICHENS

REFERENCES

Leave a Reply