Parmotrema Lichen: The Fascinating Tree Decorator You Can’t Plant But Should Appreciate
Have you ever noticed those large, leafy, gray-green growths spreading across tree bark in your yard and wondered what they are? Meet the parmotrema lichen (Parmotrema internexum), a fascinating organism that’s neither plant nor animal, but something wonderfully unique that calls North America home.
What Exactly Is Parmotrema Lichen?
Here’s where things get interesting: parmotrema lichen isn’t actually a single organism at all! It’s a partnership between a fungus and algae (and sometimes cyanobacteria) living together in perfect harmony. This biological buddy system creates those distinctive gray-green, leaf-like structures you see decorating tree trunks and branches.
The botanical name Parmotrema internexum might be a mouthful, but you might also see it referred to by its scientific synonym, Parmelia internexa. Don’t let the fancy names intimidate you – this lichen is more common than you might think.
Where Does Parmotrema Lichen Call Home?
This native North American species has made itself quite comfortable across the eastern United States, particularly thriving in the humid conditions of the Southeast. You’ll find it happily growing on the bark of various trees, from oaks to maples, adding natural character to woodland landscapes.
Identifying Parmotrema Lichen in Your Garden
Spotting parmotrema lichen is easier than you might think once you know what to look for:
- Large, leafy (foliose) growth pattern that looks almost like lettuce leaves
- Gray-green color that can appear more blue-gray in certain lighting
- Lobed edges that create an intricate, ruffled appearance
- Grows flat against tree bark, typically on the trunk and larger branches
- Size can range from a few inches to over a foot across
Is Parmotrema Lichen Beneficial for Your Garden?
Absolutely! While you can’t plant or cultivate parmotrema lichen (it grows where it wants to grow), having it appear naturally in your garden is actually a wonderful sign. Here’s why you should celebrate its presence:
- Air quality indicator: Lichens are sensitive to air pollution, so their presence suggests you have relatively clean air
- Ecosystem health: They contribute to biodiversity and provide habitat for tiny creatures
- Natural beauty: They add texture, color, and visual interest to tree bark
- No harm to trees: Despite what some people think, lichens don’t damage healthy trees – they just use the bark as a place to live
Can You Grow Parmotrema Lichen?
Here’s the thing about lichens – they’re not something you can plant in your garden like a typical flower or shrub. Parmotrema internexum grows naturally when conditions are just right, and those conditions are pretty specific. The fungal and algal partners need to find each other naturally, establish their relationship, and then slowly grow over time.
Instead of trying to cultivate lichens, the best approach is to create an environment where they might naturally appear:
- Maintain healthy, mature trees
- Avoid using harsh chemicals or pesticides
- Keep air quality as clean as possible
- Be patient – lichens grow very slowly
Living Alongside Your Lichen Neighbors
If you’re lucky enough to have parmotrema lichen growing in your landscape, consider yourself blessed with a natural work of art. These slow-growing organisms have been around much longer than your garden, and they’ll likely outlast many of your planted specimens.
The best thing you can do is simply appreciate them. Take a closer look next time you’re in your yard – notice their intricate patterns, their subtle color variations, and the way they transform ordinary tree bark into something extraordinary. They’re a reminder that some of nature’s most beautiful decorations can’t be bought at a garden center – they simply appear when the world is healthy enough to support them.
So while you can’t add parmotrema lichen to your shopping list, you can add lichen appreciation to your gardening philosophy. After all, the best gardens are partnerships between what we plant and what nature provides on its own.
