The Lichen Symbiosis Part 3

Lichen Reproduction

This is no simple matter, only the fungus of the lichen reproduces sexually. Lichens have a number of ways to spread throughout the environment, both sexually and non-sexually. The sexual stage is also complicated by the fact the mycelium can be haploid and produce self-fertile structures, due to the loss of genes, or be haploid and need a partner to form a dikaryon (the pairing but not fusion of the nuclei). The only part of the lichen that is diploid, is the asci, contained in the fruiting body the apothecia (see image 1 and 2) or perithecia, where the male and female parts have been bought together, they then form haploid spores, which does not include their algal/cyanobacteria symbiont. These spores are then forcefully ejected or washed out and dispersed within the environment; both the ascomycota and basidiomycota reproduce this way.


The result is that the ascomycota, have a number of complex systems to aid their dispersal, these are:

  • Fragments breaking off from the main thallus, these all have the capability to grow (see image 3)
  • Special areas called Isidia, outgrowths from the main thallus, specifically to be broken off and transported in some cases vast distances, by the wind, rain and animals.
  • The production of Soredia, a dust like material that contains some algal/cyanobacteria cells, wrapped up in a few hyphae, produced at the edge of the thallus, or on specialised soralium (see image 4 and 5)
  • The production of conidia contained in pycnidia, these are flask like structures on the thallus of the lichen, and this can act sexually or asexually as the spores do not contain the algae/cyanobacteria symbiont (see image 6)

I would like to thank Fay Newbery for her significant help towards creating this blog. As well as Dr Jonathan Mitchley for initial Identifications of lichens.


For British lichens, please take a look at The British Lichen Societies web page.

Or take a look at the following publications:

Nash III, H.T., 2010. Lichen Biology. 2nd ed. New York: Cambridge University Press

Gilbert, O., 2000. Lichens. London: HarperCollins

Purvis, P., 2000. Lichens. London: The Natural History Museum

Duncan, U. K. and James, P.W., 1970. Arbroath: T.buncle & CO. Ltd.

About Justin Anthony Groves

As a student of Ecology and Conservation at Reading University i am very interested many other insect groups, botany and the interaction in nature. Over a number of blogs I hope to pass my knowledge to others but also gain from the many other interesting posts.
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