An online resource based on the award-winning nature guide

Dog-tooth Lichen


Dog-tooth lichen (Peltigera canina) is often found growing on lawns and rocks.  Like all lichens, it consists of an alga or cyanobacterium and a fungus living together in a symbiotic relationship.  The fungus provides a structure for taking up moisture and nutrients; the alga or cyanobacterium is capable of photosynthesizing and producing food for both itself and the fungus.  The brown structures in the photograph are the fruiting (spore-producing) bodies of this lichen, and their resemblance to dog teeth gives this lichen its common name.  In the Middle Ages, dog-tooth lichen was used to treat rabies — it was felt at the time that this lichen’s resemblance to dog teeth indicated that it could cure dog-related ailments.

3 responses

  1. ht

    Is it possible to distinguish the alga from the fungus when examining lichen with the naked eye?

    November 17, 2011 at 1:42 am

  2. Typically the fungus surrounds the algal cells, and you would need to examine a cross-section under a microscope in order to see the differentiation of cells. When it rains, the moisture affects the opacity of the fungus so that you can see the green algae more than when the lichen is dry.

    November 17, 2011 at 4:15 am

  3. ht

    I’ll take a long look next time I’m out after a good rain. Thanks.

    November 17, 2011 at 5:13 pm

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