Lichens are stable, self‐supporting associations between a fungus and an alga or cyanobacterium.

Keywords: algae; cyanobacteria; fungi; pollution; symbiosis

Figure 1.

A mixed assemblage of lichens on the ground in a lowland heath, including Cladonia coccifera (with scarlet apothecia), C. portentosa (erect grey branched thalli), and Pycnothelia papillaria (grey crustose thallus with erect papillae). Magnification × 2. Copyright © with permission of DL Hawksworth.

Figure 2.

Vertical section through the thallus of a foliose lichen, Parmelia sulcata, showing (top to bottom) the upper cortex of compact fungal tissue, the algal layer (with Trebouxia cells stained dark blue) medulla of loosely interwoven hyphae, and the lower cortex of compacted dark brown fungal tissue. Magnification × 400. Copyright © with permission of DL Hawksworth.

Figure 3.

The lichen‐forming fungus Sticta filix. The fungus associates with cyanobacteria (Nostoc) to form shrubby blue‐grey thalli, and with green algae (Trebouxia) to produce fawn leafy thalli. Magnification × 10. Copyright © with permission of DL Hawksworth.



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Further Reading

Ahmadjian V (1993) The Lichen Symbiosis, revised edn. New York: Wiley.

Bates JW and Farmer AM (eds) (1992) Bryophytes and Lichens in a Changing Environment. Oxford: Clarendon Press.

Galun M (ed.) (1988) Handbook of Lichenology (3 vols). Boca Raton, FL: CRC Press.

Hawksworth DL (1988) The variety of fungal‐algal symbioses, their evolutionary significance, and the nature of lichens. Botanical Journal of the Linnean Society 96: 3–20.

Hawksworth DL (1994) The recent evolution of lichenology: a science for our times. Cryptogamic Botany 4: 117–129.

Kershaw KA (1985) Physiological Ecology of Lichens. Cambridge: Cambridge University Press.

Lawrey JD (1984) Biology of Lichenized Fungi. New York: Praeger.

Nash TH III (ed.) (1996) Lichen Biology. Cambridge: Cambridge University Press.

Richardson DHS (1992) Pollution Monitoring with Lichens. Slough: Richmond Publishing.

Seaward MRD (ed.) (1977) Lichen Ecology. London: Academic Press.

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How to Cite close
Hawksworth, David L(Jan 2002) Lichens. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1038/npg.els.0000368]