On noticing Nature: Lichens
By Chuck Dinsmore
If you go outside anywhere you’re likely to see lichens, even in urban environments. But if you are like me, you may not have actually noticed them as a central part of our living world. Let me then share with you my increasing appreciation for them both as esthetically delightful ornaments of our environment and as fundamental elements in Nature.
For me they have become an almost daily reminder - seeing them on trees, stones or even bare ground - of just how remarkably diverse living nature is!! Originally understood to be a symbiotic relationship between an alga and a fungus, the self-correcting process of science has thankfully advanced since then; someone discovered that the photosynthetic partner might not just be an alga (singular of algae) but could alternatively be something called ‘blue-green algae’. It turned out that while initially labeled ‘algae’, they aren’t!
Algae are related to green plants whose cells have a nucleus and also fix carbon during photosynthesis. The name blue-green algae is misleading! They’re actually a type of bacterium (no nucleus, among other differences) not only capable of photosynthesis but many are also able to ‘fix’ atmospheric nitrogen, a process critical to heathy environments, and are called cyanobacteria. You’ve probably heard about them as a potentially dangerous pollutant in our lakes and ponds. Midcoast Conservancy monitors the area’s waters, especially Damariscotta Lake, for their presence. It’s a serious health hazard when they’re found in high concentrations but otherwise they’re a normal part of balanced ecosystems! Not an issue with lichens so let’s leave discussion of the causes of ‘blooms’ for another time.
There are three general lichen forms: crustose, foliose and fruticose. Crustose lichens are the flattened growths you see on a variety of surfaces that can’t really be collected without scraping off some of the surface on which they grow. The smooth bark on a young maple tree is often completely coated with a couple of different kinds. Foliose lichens are more leaf-like, as in ‘foliage’, with the ‘leaves’ sticking up off the surface. You can usually distinguish between a ‘top’ surface and a ‘bottom’.
One common example, the yellow-green circular splotches that you sometimes see growing on the trunks of trees is from a group known as ‘shield lichens’. Fruticose lichens represent more complex 3-D forms, that is they may branch, as with ‘old man’s beard’ lichens, form little pixie cups or produce multiple tiers. The ladder lichen is one of my favorites and forms tiers making it look like miniature cascading fountains! This general grouping is useful but beware that Nature doesn’t follow our guidelines; there are many intermediates that won’t fit neatly into those three categories, and that’s okay!
As our understanding of lichens advances, so too will we discover exciting new ways of thinking about these amazing living beings. To my delight, it’s a never-ending story of discovery with many details and exceptions left for you to explore. Thank you for sharing the journey with me.
Crutose Lichens
Where’s the bark on this young maple tree? At least 3, I think, types of crustose lichen cover most of it!
Liverwort
Some liverwort (the spidery stuff on the left) photobombing these 3 crustose lichens ;-)
Foliose Lichens
These common ‘crumpled rag lichens’, staged on a piece of birch bark for convenience, are good examples of foliose lichens; they have two distinct, upper and lower, sides.
Fruticose Lichens
In my opinion, the fruticose lichens offer some of the prettiest, more complex 3-D forms. The various common ‘reindeer lichens’ fall into this category but these ladder lichens earn my admiration for their delightful architecture.
Chuck Dinsmore was born and raised in Maine where he learned early on to love and value wild places. He serves on Midcoast Conservancy’s Board of Directors, is a Maine Master Naturalist, and currently resides with his wife, Megan, in Damariscotta.
