Tube Lichen: The Fascinating Air Quality Indicator Growing on Your Trees
Have you ever noticed those interesting gray-green, crusty growths on tree bark and wondered what they are? Meet the tube lichen (Hypogymnia subobscura), a remarkable organism that’s neither plant nor animal, but something wonderfully unique that might already be calling your garden home.
What Exactly Is Tube Lichen?
Tube lichen is a fascinating composite organism made up of fungi and algae living together in perfect harmony. This partnership, called symbiosis, allows lichens to thrive in places where neither organism could survive alone. The scientific name Hypogymnia subobscura might be a mouthful, but you might also see it referred to by its synonym Parmelia subobscura in older field guides.
Unlike the plants we typically think about for our gardens, lichens don’t have roots, stems, or leaves. Instead, they form flat, leaf-like structures that attach directly to surfaces like tree bark, creating those distinctive crusty or leafy patches you’ve probably spotted.
Where You’ll Find Tube Lichen
This native North American species is particularly common in the western regions, especially throughout the Pacific Northwest’s forests. If you live in an area with clean air and mature trees, you might be lucky enough to have tube lichen already establishing itself naturally in your landscape.
How to Identify Tube Lichen
Spotting tube lichen is easier than you might think once you know what to look for:
- Gray-green coloration that may appear slightly bluish in certain light
- Foliose (leaf-like) growth pattern that lies relatively flat against tree bark
- Distinctive tube-like structures that give this lichen its common name
- Typically found on the bark of mature trees, especially conifers
- Size ranges from small patches to larger colonies covering significant portions of bark
Is Tube Lichen Beneficial for Your Garden?
Absolutely! While you can’t plant or cultivate tube lichen like traditional garden plants, its presence is actually a wonderful sign. Here’s why you should be thrilled to discover it:
Air Quality Indicator: Lichens are incredibly sensitive to air pollution, so finding tube lichen in your garden means you have clean, healthy air. They’re like nature’s own air quality monitors!
Ecosystem Health: The presence of diverse lichen species indicates a healthy, balanced ecosystem. They’re part of the natural succession that helps create rich forest environments.
Wildlife Support: While lichens don’t attract pollinators like flowering plants, they do provide food for various wildlife species and nesting materials for birds.
Natural Beauty: Tube lichen adds authentic, wild character to your landscape, creating the kind of natural patina that makes gardens feel established and connected to local ecosystems.
Creating Lichen-Friendly Conditions
You can’t plant tube lichen, but you can create conditions that encourage its natural establishment:
- Maintain mature trees with textured bark – lichens love older trees
- Avoid using pesticides or fungicides that might harm these sensitive organisms
- Keep air quality clean by supporting environmental practices
- Be patient – lichens grow very slowly and establish over years or decades
- Don’t try to remove or transplant lichens, as this typically kills them
Garden Design Considerations
Tube lichen fits beautifully into naturalistic and woodland garden designs. If you’re aiming for that authentic forest feel, having lichens on your trees is like receiving nature’s stamp of approval. They work particularly well in:
- Native plant gardens
- Woodland settings
- Naturalistic landscapes
- Mature, established gardens
The Bottom Line
While you can’t add tube lichen to your shopping list at the garden center, discovering it growing naturally in your landscape is cause for celebration. It means you’re providing habitat for this fascinating organism and maintaining the kind of clean, healthy environment where native species can thrive.
Rather than trying to cultivate lichens, focus on creating the conditions they love: mature trees, clean air, and minimal chemical interference. Sometimes the best gardening approach is simply stepping back and letting nature work its magic. When tube lichen chooses your garden, you’ll know you’re doing something right!
