Friday, April 2, 2010


I’m about to get quite busy for the month of April which is great but I may have to slow the pace of my posting. This will probably be fine considering there hasn’t been a ton of responses to my posts, yet. I wanted to try to answer as many of the questions about lichens as possible. The photo above isn’t the best but it is the only example of a lichen I could find in my collection.

Lichens are a kind of text book example of symbiosis. Symbiosis means “living (bios) together (sym).” It is whenever two organisms form a relationship in which both benefit. Sometimes these relationships are necessary for the survival of one or both members and sometimes the organisms can live without them. In the case of lichens it is a relationship between a fungus and either a green alga or a cyanobacteria. These two kinds of organisms are both single-celled, photosynthetic creatures whose cells contain the same kind of chlorophyll as land plants’ chloroplasts.

Lichens acquire their food entirely through photosynthesis. So why do those little one-celled creatures need the fungus? They don’t. Most species of alga and cyanobacteria that are found in lichens can and do survive by themselves. But there is an advantage to forming a relationship with the fungus. Lichen-forming fungi produce a substance that speeds photosynthesis, making it a bit more efficient. They also absorb enough water for both the fungus and their photosynthetic friends so these cells don’t need to worry about getting water. It seems to be a very good advantage for the unicellular symbionts because many lichen-forming fungus species actually parasitize the chlorophyll containing cells.

They do not, however, tend to parasitize the trees they may be growing on. Most lichens use their growing surface simply as a substrate and do not have roots or other structures that take nutrients from below.

The coolest fact I found about lichens is that some species can live up to 4500 years. I don’t know what the life spans of most fungus are but that seemed pretty impressive.

It’s interesting how much parasitism, symbiosis and commensalism have already come up on the mycelial network. This is a perfect illustration of how the biological world is not set out in discrete parts but forms a web of interactions and relationships; it forms an ecology. What are some of your favorite examples of organisms living together (whether parasitically or not)?


  1. lichens also produce a purple dye~ woohoo~

    i am a big fan of chaga, both medicinally and biologically. medicinally, it is quite powerful (yet gentle) on the immune system and has/is being studied for its effects on cancer and HIV treatments. It's also wondeful to blend in chai and is a great coffee substitute (minus the caffiene).

    on a biological note, the growth process is still a bit of a mystery (despite what all the info out there will say). it's considered a fungus, but it doesn't have spores and doesn't grow in abundance like some fungii can.

    it grows on bitch trees, but once it starts to grow on a birch, it means that the tree is in ill health. chaga, for it to become large, takes many years to grow; but once you harvest the chaga, the tree will then die. so, in a way, the chaga keeps the tree alive, even though it only grows on hurt trees (it usually grows on the birch if a 'wound' has presented on the birch).

    it truly is like a cancerous tumour that growns on the wound. while the growth process is still being researched, i take delight in the mystery of it. i feel as though it adds to the medicine.

    chaga is a super friend to me~ it helped me big time when recovering from all those surgeries. i also love how a little goes a long way, and it can be decocted twice and still have the same potency as the first brew. the taste is lovely; very woody/earthy, but not bitter or soil-like. its very mellow, but dark, rich and smooth, which is why it's such a great coffee substitute. i love to blend it in my chai recipe and its a wonderful winter 'herb' to have in the pantry.

    and i really do mean it goes a long way~ i bought 8 ounces in 2008, and i still have plenty of it. so little needs to be used. the big problem with chaga is, since more info has been coming out that it has powerful effects on the immune system, it has been severly over harvested; which means that birch forests are dying at a faster rate. conservation education for harvesting and using chaga needs to be implemented, or there are going to be big problems for birch forests.

  2. I wonder what other conservation issues relate to fungus and/or lichens. I don't come across them much either as invasives or as protected. That's an interesting story about the chaga.

  3. chaga is super awesome, and someday i'll make you a cup o' chaga chai!