Rimmed Navel Lichen: A Fascinating Rock-Dwelling Organism in Your Landscape
Have you ever noticed crusty, colorful patches growing on rocks in your garden or while hiking? You might have encountered the rimmed navel lichen (Rhizoplaca melanophthalma), one of North America’s most distinctive rock-dwelling organisms. While you can’t exactly plant this fascinating species in your garden, understanding what it is and recognizing its presence can deepen your appreciation for the incredible diversity of life that naturally occurs in our landscapes.
What Exactly Is Rimmed Navel Lichen?
First things first – rimmed navel lichen isn’t actually a plant! It’s a lichen, which is a remarkable partnership between fungi and algae working together as a single organism. This cooperative relationship allows lichens to thrive in some of the harshest environments on Earth, including bare rock surfaces where traditional plants simply can’t survive.
The scientific name Rhizoplaca melanophthalma might be a mouthful, but it’s also known by several other scientific names including Lecidea brandegeei and Lecanora melanophthalma, reflecting the complex history of lichen classification.
Where You’ll Find This Native Species
Rimmed navel lichen is native to North America, where it has been quietly doing its job for thousands of years. You’ll most commonly spot this species in the western regions of the continent, particularly in arid and semi-arid areas where it decorates rock faces, boulders, and stone outcrops.
Identifying Rimmed Navel Lichen
Spotting rimmed navel lichen is like finding nature’s own abstract art. Here’s what to look for:
- Circular to irregular crusty patches growing directly on rock surfaces
- Yellowish-green to gray-green coloration
- Distinctive dark margins that give it the rimmed appearance
- Flat, tightly attached growth that seems painted onto the rock
- Size can vary from small spots to larger patches several inches across
Is Rimmed Navel Lichen Beneficial to Your Garden?
While you can’t cultivate rimmed navel lichen like you would a flower or shrub, its presence in your landscape is actually quite beneficial:
- Helps break down rock surfaces over time, contributing to soil formation
- Provides habitat and food sources for small invertebrates
- Indicates good air quality, as lichens are sensitive to pollution
- Adds natural color and texture to rock features
- Requires zero maintenance while providing year-round interest
Creating Lichen-Friendly Conditions
Rather than trying to grow rimmed navel lichen, you can encourage its natural establishment by:
- Incorporating natural rock features into your landscape design
- Avoiding chemical treatments near rock surfaces
- Maintaining good air circulation around stone features
- Being patient – lichens establish and grow very slowly
- Keeping rock surfaces free from excessive organic debris
The Bigger Picture
Finding rimmed navel lichen in your landscape is actually a sign of a healthy ecosystem. These remarkable organisms are pioneers, often among the first life forms to colonize bare rock surfaces. Over time, they help create conditions that allow other plants to eventually establish, making them important contributors to ecological succession.
So the next time you’re admiring the rocks in your garden or exploring natural areas, take a moment to appreciate these often-overlooked organisms. Rimmed navel lichen might not be the showiest addition to your landscape, but it’s certainly one of the most resilient and ecologically important. Plus, there’s something deeply satisfying about being able to identify and appreciate the quiet work these remarkable partnerships are doing right under our noses.
