12 November 2024
Many of us go to Homewood Cemetery to see birds like this merlin in December 2020, but there are many other attractions and some of them are subtle. Did you know the cemetery is a good place to find lichens?
Lichens are two organisms that operate as one, a symbiotic partnership of a fungus with a green or blue-green algae, sometimes all three. The algae’s photosynthesis feeds the fungus. The fungus gathers water and nutrients and protects the algae. This combination allows lichens to thrive in some of the harshest places the planet but they are sensitive to air pollution. Those that grow on trees and tombstones are totally dependent on the surrounding air and precipitation for their nutrition. Ultimately their tissues absorb elements in concentrations that mimic what’s in the air.
Since lichens are indicators of air quality, it was natural that GASP (the Group Against Smog Pollution) would hold a lichen walk at Homewood Cemetery on 2 November led by GASP’s Laura Kuster and cemetery historian Jennie Benford.
We didn’t have to walk far to find lichens.
They look like rumpled leaves stuck to the headstone. The leaves are reaching into the air.
The lichen’s shape gives an indication of local air quality.
- Flat lichens (Crustose) have the least air exposure and can survive in relatively bad air.
- Those that look like crumpled leaves (Foliose) can survive in medium air quality — not good but not bad air. We saw a lot of these at Homewood Cemetery.
- Shaggy lichens that drip in open bunches (Fruticose) have the highest air exposure and need really good air quality to survive. We did not see any of these at Homewood Cemetery.
Next time you’re at Homewood Cemetery check out the lichens. When you find the Howard Irish tombstone you’ve hit the jackpot!
I had a beautiful maple tree covered in lichens. I didn’t know until a few years ago that it was not a sign that the tree was dying, but a sign the air was good!
Kate, this scientific insight into the lives of lichens I’ve witnessed thriving from New Hampshire’s tallest peaks to Penn’s Woods is the best I can remember, and it gives me even more respect for them beyond their beauty. Thank you!