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What are lichens

2012 September 27
by Robert

By Ken Moore

Busy-beard lichen, Usnea strigosa, is a common fruticose form found on trees. Photo by Gary Perlmutter

Lichens are pioneer plants, colonizers on boulders and other bare surfaces, slowly developing layers of soil particles for the establishment of larger plant communities. They are diverse and beautiful and frequently engage us to pause for an admiring closer look. If you’re like me, you most likely move on, wishing you knew more about lichens.

These are the times we need the company of one of those rare “lichenologists” like Gary Perlmutter, who for several years has been engaged in surveying the lichens of our Piedmont region.

I attended the one-day lichen workshop that Gary led about this time last year. It was great. He’s offering another one-day “Introduction to Lichens” coming up soon. The workshop will be held at the N.C. Botanical Garden on Saturday, Oct. 13 ( for more information).

This is not to be missed if you are curious about lichens.

I am repeating last year’s brief and engaging description of lichens by Gary. If you missed it last year, you’ll most likely be appreciative. Otherwise, if you’re like me, a review is more than welcome.

“Just what are lichens anyway?

At least six different species of crustose, foliose or fruticose lichens are growing on this boulder surface. Photo by Gary Perlmutter

When out in the woods or even in your backyards, you often admire the trees, shrubs and wildflowers. But if you look closer on the trees, rocks and soil, you’ll see little colorful, plant-like things quietly growing on them. They may look like splotches of paint, ruffled leaves or tiny shrubs. These aren’t plants at all, but strange life forms called lichens.

Lichens are symbiotic organisms, consisting of a fungus and a photosynthetic partner living together as one. I say “photosynthetic partner” because it could be a green alga, which is a plant, or a blue-green alga, which is really a type of bacteria.

Dark squiggly lines on a holly tree trunk are common script lichens, Graphis scripta. Photo by Gary Perlmutter

Recent research has revealed the relationship is even more complicated, with entire communities of bacteria living inside lichens. Some researchers consider lichens not as individuals, but entire ecosystems in miniature.

We lichenologists use the term ‘thallus’ to describe a lichen body. To blur things further, a lichen thallus can be a single lichen or a colony of several lichens merged into one.

Generally lichens come in three growth forms or body types: ‘crustose’ (crust-like), ‘foliose’ (leaf-like) and ‘fruticose’ (shrub-like). And they come in a wide array of colors, from black to brown, to green, blue, yellow, orange, red and white. Most are a grayish-green.

Given enough time, lichens grow on just about anything. They are found on bare soil, rocks, wood, moss and even on the bark of trees, from the roots up the trunk and to the canopy branches and twigs. Some lichens grow on other lichens, crowding each other as they compete for light and space. Sometimes if you pick up a fallen branch you’ll see it’s completely covered with several different kinds of lichens – a community unto itself. In the natural world you are never far from a lichen.”

Join Gary for his class and become the first “lichenologist” in your neighborhood.

And thank you, Gary for introducing Flora readers to the world of lichens.

Email Ken Moore at Find previous Ken Moore Citizen columns at The Annotated Flora.

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