North America Native Plant

Degel’s Rim Lichen

Botanical name: Squamarina degelii

USDA symbol: SQDE

Habit: lichen

Native status: Native to North America  

Degel’s Rim Lichen: A Fascinating Natural Rock Decorator Have you ever noticed small, crusty patches of gray-green growth on rocks in your garden or while hiking? You might have encountered Degel’s rim lichen (Squamarina degelii), a fascinating organism that’s neither plant nor animal, but something wonderfully unique in between. What ...

Degel’s Rim Lichen: A Fascinating Natural Rock Decorator

Have you ever noticed small, crusty patches of gray-green growth on rocks in your garden or while hiking? You might have encountered Degel’s rim lichen (Squamarina degelii), a fascinating organism that’s neither plant nor animal, but something wonderfully unique in between.

What Exactly Is Degel’s Rim Lichen?

Before we dive deeper, let’s clear up what a lichen actually is. Lichens are remarkable partnerships between fungi and algae (or sometimes cyanobacteria) that work together to create something neither could achieve alone. The fungus provides structure and protection, while the algae produces food through photosynthesis. It’s like nature’s perfect roommate situation!

Degel’s rim lichen appears as small, crusty patches that form tight, grayish colonies on rock surfaces. This hardy little organism is native to North America and has adapted to survive in some pretty tough conditions.

Where You’ll Find This Rocky Resident

This lichen calls North America home, with populations particularly thriving in the arid and semi-arid regions of the western United States. You’ll typically spot it growing on exposed rock surfaces, where it forms distinctive crusty patches that blend beautifully with the natural stone.

Is Degel’s Rim Lichen Beneficial to Your Garden?

While you can’t exactly plant Degel’s rim lichen in your flower beds, its presence in your garden can actually be a wonderful sign. Here’s why:

  • Air quality indicator: Lichens are sensitive to air pollution, so their presence suggests you have relatively clean air in your area
  • Natural beauty: They add subtle, natural character to rock walls, stone pathways, and boulder features
  • Ecosystem support: While not a pollinator magnet, lichens contribute to the broader ecosystem by slowly breaking down rock surfaces and creating soil over time
  • Low maintenance: They require absolutely no care from you – they’re the ultimate low-maintenance garden residents

How to Identify Degel’s Rim Lichen

Spotting this lichen is easier than you might think once you know what to look for:

  • Appearance: Forms small, crusty, grayish patches on rock surfaces
  • Texture: Has a distinctive crusty or granular texture that’s firmly attached to the rock
  • Color: Typically gray to gray-green, sometimes with subtle variations depending on environmental conditions
  • Location: Almost exclusively found on exposed rock surfaces rather than soil or bark

Creating Lichen-Friendly Conditions

While you can’t plant lichens like traditional garden plants, you can create conditions that welcome them naturally:

  • Include natural stone features: Rock walls, stone pathways, and boulder placements provide perfect surfaces
  • Minimize chemical use: Avoid harsh chemicals near stone features, as lichens are sensitive to pollutants
  • Be patient: Lichens grow incredibly slowly – we’re talking millimeters per year – so don’t expect overnight results
  • Resist the urge to scrub: If lichens appear on your stone features, celebrate rather than remove them

The Bottom Line

Degel’s rim lichen might not be the showstopper flower you plant for spring color, but it’s a fascinating addition to any naturalistic garden design. Think of it as nature’s way of adding character and authenticity to your stone features. Plus, its presence is essentially a compliment – it’s telling you that your garden environment is clean and healthy enough to support these sensitive organisms.

So next time you spot those gray, crusty patches on your garden rocks, take a moment to appreciate these amazing partnerships between fungi and algae. They’re quietly doing their part to make your outdoor space a little more wild and wonderful, one tiny patch at a time.

Degel’s Rim Lichen

Classification

Group

Lichen

Kingdom

Fungi - Fungi

Subkingdom
Superdivision
Division

Ascomycota - Sac fungi

Subdivision
Class

Ascomycetes

Subclass
Order

Lecanorales

Family

Bacidiaceae Walt. Watson

Genus

Squamarina Poelt - rim lichen

Species

Squamarina degelii Frey & Poelt - Degel's rim lichen

Plant data source: USDA, NRCS 2025. The PLANTS Database. https://plants.usda.gov,. 2/25/2025. National Plant Data Team, Greensboro, NC USA