In this article we will discuss about:- 1. Definition of Lichens 2. Structure of Lichens 3. Relationships 4. Reproduction. Definition of Lichens: Lichens are dual organisms or entities which contain a permanent association of a fungus or mycobiont and an alga or phycobiont. The fungal partner is usually an Ascomycota and sometimes, a basidiomycete. The algal partner is mostly a [...]
The following points highlight the two main examples of lichens. The examples are: 1. Parmelia 2. Usnea. Example # 1. Parmelia: It is a common example of a foliose lichen which is found growing on the bark as well as the rock intermixed with the mosses at higher altitude (above 4,000 ft.). The heteromerous thallus is lobed to deeply incised. [...]
On the basis of internal structure of thallus, the lichens are divided into two groups, namely, homoiomerous and heteromerous lichens. 1. Structure of Homoiomerous Lichen Thallus: In the gelatinous lichen thalli such as Collema and Leptogium, the thallus shows a simple structure with little differentiation. It consists of a loosely interwoven mass of fungal hyphae with algal cells equally distributed [...]