Nature Notes: Looking for Lichens
- Delaney Dahl
- 10 minutes ago
- 3 min read
As winter passes and we move into spring, thinking back on the wonders of winter becomes significantly more enjoyable. When you're in the middle of winter, looking out, it’s easy to assume that nature has gone to sleep. But when you have a chance to look back from the outside, you probably noticed that life didn't disappear at all. It simply changed scale.
Clinging to tree bark, dusting rocks, and brightening fallen branches are lichens: small, often overlooked organisms that bring color and fascinating life to the winter landscape.
What Exactly is a Lichen?
A lichen isn’t a single organism, but an example of symbiosis. It’s made up of a fungus and an alga living together so closely they function as one. The fungus provides structure and protection, while the alga produces food through photosynthesis. Together, they form a resilient team capable of surviving in some of the harshest conditions.
Lichens rely on sunlight and moisture to grow, which means winter sends them into a dormant state. Even so, they remain an important part of the ecosystem, offering food for wildlife and adding texture and color to an otherwise quiet season.
A Closer Look: Common Lichens of the Northwoods
If you’re wandering trails in places like Minnesota or Wisconsin, you don’t have to look far to find lichens. Here are a few you might spot:
Common Greenshield
One of the most widespread lichens in the region, common greenshield is a soft green color and grows directly on tree bark. It has a foliose form, meaning it looks leafy with broad, lobed edges. Smooth when young, it may wrinkle as it ages. A close relative, speckled greenshield, looks similar but features tiny white spots scattered across its surface.
Sunburst Lichen
If you notice a flash of bright orange or yellow on a branch or tree trunk, you’ve likely found a sunburst lichen. These striking lichens often feature small, cup-like structures called apothecia which appear as darker orange discs. Though some grow on rocks, others, like poplar sunburst, prefer tree bark. Their bold color is especially eye-catching against a winter backdrop.
British Soldier Lichen
Tiny but unforgettable, British soldier lichens pop up on decaying wood, stumps, and forest floor debris. They have a fruticose (shrub-like) growth form, with slender stalks topped by bright red caps.Interestingly, while they produce spores, these spores contain only the fungal partner. To truly reproduce, the lichen relies on fragments breaking off and establishing elsewhere.
Mapledust Lichen
Unlike leafy or shrubby lichens, mapledust lichen is crustose, meaning it forms a thin, crust-like layer tightly attached to its surface. Often pale green or gray, it can look like dust or even a splash of paint on tree bark or rock. As the name suggests, it’s commonly found on trees in the maple family.
Friend, Not Foe
If you spot lichens growing on your trees, there’s no need for concern. Lichens don’t harm their hosts, they simply use bark as a place to live. They gather nutrients from the air and rain, not from the tree itself. In fact, their presence often indicates good air quality and a healthy environment.
A Winter Invitation
Lichens remind us that even in the quietest seasons, life persists in remarkable ways. They reward curiosity and patience, inviting us to slow down and notice the details we might otherwise miss.
So next time you’re out on a walk (even in winter), take a moment to look closer at the trees, rocks, and fallen branches around you. What first appears to be a simple patch of color may reveal a complex, beautiful partnership, quietly thriving all along.
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