Lichens

LICHENS DETAILS

1. LICHENS PRESENTED BY : AQIL QURESHI UNIVERSITY OF EDUCATION TOWNSHIP CAMPUS

2. Introduction Structure of Lichens Forms of Lichens Classification of Lichens Species and Common Naming of Lichens Vegetative Reproduction Asexual and Sexual Reproduction Economic Importance of Lichens Contents

3. Order : Lechano Rales Kingdom : Fungi Genus : Lichens The intimate symbiotic association of fungi and algae is called lichens. The algae of lichens mostly belong to chlorophyta and cynobacteria . Lichens are abundant growing on bark, leaves and mosses. The fungus is called mycobiont . The photosynthesizing organism is called a photobiont . Introduction

4. The part of lichen that is not involved in reproduction is called Thallus . Thallus is composed of following parts: Upper Cortex Algal Zone Medulla Lower Cortex Upper Cortex: Cortex is a protective skin of densely packed fungal filaments. Upper cortex present on the top side. Structure of Lichens

5. Structure of Lichens

6. Algal Zone : These are often enclosing algae within complex fungal tissues. Structure of Lichens

7. Structure of Lichens

8. Algal Zone : These are often enclosing algae within complex fungal tissues. Medulla : It is the central part of the thallus . It forms the main part of thallus . These are the conductiong cells. Structure of Lichens

9. Structure of Lichens

10. Algal Zone : These are often enclosing algae within complex fungal tissues. Medulla : It is the central part of the thallus . It forms the main part of thallus . These are the conductiong cells. Lower Cortex : It is present below the medulla. It is a narrow layer of compactly arranged hyphae . Structure of Lichens

11. Structure of Lichens

12. The lichens are divided into three groups on the basis of thallus . Crustose Lichens :The thallus from crust like structure. It is closely adhere to the substrate. Example : Graphics Foliose Lichens : In this case, thallus has leaf like lobes. They are free from the substrate. Example : Physcia , Permellia . Fructicose Lichens : The thallus are cylindrical ribbon like and branched. Example : Cladonia , Usnea Forms of Lichens

13. Forms of Lichens

14. There are two groups of lichens: Ascolichens : In this case, lichens belong to Ascomycota . Majority of the lichens belongs to this group. Basidiolichens : In this case, lichens belong to Basidomycota . Classification of Lichens

15. There are about 20,000 known species of lichens. Some lichens have lost the ability to reproduce sexually. But they are still taken as specie. Common names for lichens may contain the word moss like Reindeer moss and Iceland moss . Species and Common Naming of Lichens

16. Vegetative reproduction occurs by different methods: Fragmentation : It is most effective way of reproduction. It is found in foliose and fruticose lichens. Mechanical stress or death of some cells breaks the thallus into fragments. Each fragment has growing areas. There growing areas grow to form new thallus . Isidia :These are small papilla like outgrowths. These are present on the upper surface of thallus . Vegetative Reproduction

17. Each isidium is composed of algal cells and fungal hyphae . Isidia detach from the body. Isidia are found in Permellia etc. Soredia : Soredia are small bud like outgrowths formed on the surface of thallus . Soredia are composed of many algal cells with few fungal hyphae . Vegetative Reproduction

18. Vegetative Reproduction

19. Cephalodia : They are external or internal gall like outgrowths. They are dark in colour . They consist of fungal hyphae enclosed in algal cells. Vegetative Reproduction

20. Vegetative Reproduction

21. Asexual reproduction takes place by pycnidiospores , conidia oidia formation. In some cases, hyphae break down into small pieces known as oidia . While pycniospores are produced within the flask shaped structures known as pycnidia . Sexual reproduction is oogamous , Ascogonium and spermatia are formed. Oogamous characterized by fusion of a small actively motile male gamete and a large immobile female gamete. Asexual and Sexual Reproduction

22. Ascogonium The female sex organ in ascomycetous fungi. The hyphae , in fungi of the Ascomycota , that grow from the ascogonium after it has fused with the antheridium . Spermatia A nonmotile male gamete, as in red algae and certain fungi. Colorless cell of certain fungi and lichens, developed within spermagonia . Asexual and Sexual Reproduction

23. Role in nitrogen fixation Food Biodegradation As dyes Antibiotic metabolites Traditional medicine Economic Importance of Lichens

24. Role in Nitogen Fixation : Cynobacteria are involved in nitrogen fixation.This nitrogen increases the fertility of soil. Food: some used as a staple food.It was cooked as a bread, pudding, soup, or salad. Biodegradation :Lichens can degrade polyester resins. As dyes: Many lichens produce secondary compounds and pigments. Economic Importance of Lichens

25. Antibiotic Metabolites : Lichens produce metabolites. These are useful in the medical community. A few are associated to antiseptic. Traditional Medicine: Lichens are also used in nonscientific traditional medicine practices of many cultures. Economic Importance of Lichens