North America Native Plant

Skin Lichen

Botanical name: Leptogium milligranum

USDA symbol: LEMI20

Habit: lichen

Native status: Native to North America  

Skin Lichen: The Tiny Garden Helper You Never Knew You Had If you’ve ever taken a close look at the bark of trees in your yard or noticed small, crusty patches on rocks, you might have spotted skin lichen (Leptogium milligranum) without even realizing it! This fascinating little organism is ...

Skin Lichen: The Tiny Garden Helper You Never Knew You Had

If you’ve ever taken a close look at the bark of trees in your yard or noticed small, crusty patches on rocks, you might have spotted skin lichen (Leptogium milligranum) without even realizing it! This fascinating little organism is more common than you’d think, and it’s actually doing some pretty amazing work in your outdoor spaces.

What Exactly Is Skin Lichen?

First things first – skin lichen isn’t actually a plant at all! It’s what scientists call a composite organism, made up of a fungus and algae living together in perfect harmony. Think of it as nature’s ultimate roommate situation, where both partners benefit from the arrangement. The fungus provides structure and protection, while the algae produces food through photosynthesis.

Leptogium milligranum gets its common name skin lichen from its thin, somewhat skin-like appearance when it grows on surfaces. You’ll typically find it as small, grayish to brownish patches with a granular or slightly crusty texture.

Where You’ll Find This Native Beauty

This lichen is native to North America and can be found across temperate regions of the continent. It’s not picky about where it sets up shop – you might spot it on tree bark, rocks, soil, or even old wooden structures in your garden.

How to Identify Skin Lichen

Spotting skin lichen in your garden is easier than you might think once you know what to look for:

  • Small, thin patches that look almost like dried skin or paper
  • Grayish to brownish coloration
  • Granular or slightly crusty surface texture
  • Usually found in shaded, moist areas
  • Grows flat against surfaces rather than standing upright
  • Often forms irregular, spreading patches

Is Skin Lichen Good for Your Garden?

Absolutely! While you can’t plant or cultivate skin lichen like traditional garden plants, having it show up naturally in your outdoor spaces is actually a wonderful sign. Here’s why you should be happy to see it:

  • Air quality indicator: Lichens are incredibly sensitive to air pollution, so their presence suggests you have relatively clean air in your garden
  • Ecosystem health: They contribute to biodiversity and create microhabitats for tiny creatures
  • Natural beauty: They add interesting textures and subtle colors to natural surfaces
  • Soil building: Over time, lichens help break down rocks and contribute to soil formation

Creating Lichen-Friendly Conditions

While you can’t exactly grow skin lichen, you can encourage its natural presence by creating the conditions it loves:

  • Maintain areas with partial to full shade
  • Keep some moisture in the air (avoid overly dry conditions)
  • Minimize air pollution around your property
  • Leave natural surfaces like tree bark and rocks undisturbed
  • Avoid using harsh chemicals or pressure washing in areas where lichens grow

Living Alongside Your Lichen Neighbors

The best part about skin lichen is that it requires absolutely no maintenance from you – in fact, the less you interfere, the better! These remarkable organisms thrive when left to their own devices in naturally occurring conditions.

If you notice skin lichen in your garden, consider it a compliment to your environmental stewardship. It means you’re providing habitat for these fascinating composite organisms and contributing to local biodiversity. Plus, you get to enjoy the subtle beauty and interesting textures they add to your outdoor spaces – all without lifting a finger!

So the next time you’re wandering through your garden, take a moment to appreciate these tiny marvels. They might be small, but they’re mighty contributors to the complex web of life that makes your outdoor space truly special.

Skin Lichen

Classification

Group

Lichen

Kingdom

Fungi - Fungi

Subkingdom
Superdivision
Division

Ascomycota - Sac fungi

Subdivision
Class

Ascomycetes

Subclass
Order

Lecanorales

Family

Collemataceae Zenker

Genus

Leptogium (Ach.) A. Gray - skin lichen

Species

Leptogium milligranum Sierk - skin lichen

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