A Fungi And Algae Love Story: HCT Walk Illuminates World Of Lichens

HARWICH – Just when you think you might be a keen observer of nature, along comes Harwich Conservation Trust naturalist Tom Walker to blow your mind. A few steps into our Hikin' for Lichens walk at Thompson's Field, something surprising was revealed: lichens are everywhere!

Sure, we had seen lichens on trees, but once an expert was on hand to point things out, the breathtaking variety and ubiquitous placement of these organisms came into focus. And their biological backstory is one of those things that makes you go “huh?” and then marvel at the amazing ways that nature keeps chugging along.

Walker had a cool and humorous way of explaining the composition of lichens: “Freddie Fungus and Alice Algae took a liking to each other,” he said. “Freddy Fungus has all these great life skills, a great big apartment, but he doesn't know how to cook. He can't make his own food. And Alice Algae is a homeless master chef. So, the two of them move in together and become this very successful symbiotic organism.”

This relationship provides food for the fungus, which the algae produces from photosynthesis. In turn, the fungus provides the algae with protection from excess sunlight, predators and abrasion. This “love story” might not be particularly romantic, but it sure is efficient!

And these lichens get around. They cover somewhere between five and 10 percent of the earth's surface, in a wide variety of habitats that include deserts, mountains and polar regions. You'll find them on tree bark, soil and rocks, and human-made stuff like tombstones and fences. Walker pointed out some brilliantly-colored marine sunburst lichen happily growing on the shingles above the Thompson's Field kiosk. 

While they seem unstoppable, these resilient organisms have enemies. “Habitat loss and air pollution,” said Walker. “Lichens need stable environments and clean air.”

Happily, the Cape qualifies as a top-notch environment for lichens. “Cape Cod has got great clean air, because we're surrounded by the ocean," said Walker. “There's always a constant breeze pushing the pollutants away. Plus, there's lots of moisture. Lichens need moisture to get going.”

You may wonder if lichen can harm trees. The general answer is a slightly nuanced “no,” said Walker. 

The University of New Hampshire Extension puts it this way: “Since lichens are often found growing on the bark of trees that are in poor health, it is often assumed that they are to blame. However, the relationship between the lichens and the tree is largely benign, and the decline of the tree is the result of some other stressor. Even though a lichen can absorb some mineral nutrients from the surface it is growing on, it is primarily self-sufficient.”

Walker introduced us to a variety of lichens as we moved along the trail. Favorites included bushy beard lichen, a grayish-green tuft that festoons tree branches throughout the woods at Thompson's Field and evokes thoughts of Rip Van Winkle's facial hair after his 20-year nap.

Perhaps the most beautiful species observed on our journey was the British soldier lichen, which the Missouri Department of Conservation calls a “rock star” because of its bright red spores. It's only about an inch tall and grows around decaying wood, mossy logs and tree stumps.

Getting a good look at this miniature but spectacularly beautiful lichen was a real treat, made better because Walker provides hand lenses to program participants.

That kind of attention to detail is what makes a Harwich Conservation Trust nature walk an illuminating treat. You learn a lot, make new friends, enjoy Cape Cod's natural beauty, and in this case, go home and tell all your friends that lichens are awesome!

Want to learn more about lichens? Join HCT's Hikin' for Lichens program at Thompson's Field Conservation Area on Dec.19. from noon to 2 p.m. The price is $15. To reserve your spot, visit harwichconservationtrust.org/events.