North America Native Plant

Arsene’s Skin Lichen

Botanical name: Leptogium arsenei

USDA symbol: LEAR16

Habit: lichen

Native status: Native to North America  

Arsene’s Skin Lichen: A Mysterious North American Lichen Worth Knowing If you’ve ever taken a close look at the bark of trees in your yard or local forest, you might have spotted something that looks like a thin, leafy growth clinging to the surface. Meet Arsene’s skin lichen (Leptogium arsenei), ...

Arsene’s Skin Lichen: A Mysterious North American Lichen Worth Knowing

If you’ve ever taken a close look at the bark of trees in your yard or local forest, you might have spotted something that looks like a thin, leafy growth clinging to the surface. Meet Arsene’s skin lichen (Leptogium arsenei), one of North America’s more elusive lichen species that’s quietly going about its business in our natural landscapes.

What Exactly Is a Lichen?

Before we dive into the specifics of Arsene’s skin lichen, let’s clear up what lichens actually are. They’re not plants in the traditional sense – they’re fascinating partnerships between fungi and algae (or sometimes cyanobacteria) that work together to create something entirely unique. The fungus provides structure and protection, while the algae handles the food production through photosynthesis. It’s like nature’s ultimate roommate situation!

Getting to Know Leptogium arsenei

Arsene’s skin lichen belongs to a group called foliose lichens, which means it has a leaf-like appearance rather than forming crusty patches or branching structures. This particular species is native to North America, though specific details about its exact range and distribution remain somewhat mysterious – even to scientists who study lichens for a living.

When dry, this lichen typically appears bluish-gray to brownish, but here’s where it gets interesting: when moisture hits it, the lichen transforms to a greenish color as it becomes active again. It’s like watching a tiny ecosystem wake up!

Where You Might Spot It

Arsene’s skin lichen isn’t particularly picky about its real estate – you’ll typically find it growing on:

  • Tree bark (especially on older trees)
  • Rock surfaces
  • Areas with moderate moisture levels

Don’t expect to find it everywhere, though. This species seems to be somewhat uncommon, which adds to its intrigue for lichen enthusiasts and nature lovers alike.

Is It Beneficial to Your Garden?

While you can’t exactly plant Arsene’s skin lichen in your garden bed like you would a tomato, having lichens around is actually a pretty good sign. Here’s why they’re garden-friendly neighbors:

  • Air quality indicators: Lichens are sensitive to air pollution, so their presence suggests you’ve got relatively clean air in your area
  • Ecosystem health: They contribute to biodiversity and can provide food for various small creatures
  • Natural beauty: They add subtle texture and color to tree bark and rocks
  • No harm done: Unlike some growths, lichens don’t damage their host trees or structures

How to Identify Arsene’s Skin Lichen

Identifying specific lichen species can be tricky business, even for experts, but here are some general characteristics to look for:

  • Thin, leaf-like appearance that lies fairly flat against its surface
  • Color changes from bluish-gray/brown when dry to greenish when wet
  • Found on bark and rock surfaces
  • Part of the Leptogium genus (skin lichens)

Keep in mind that definitive identification often requires microscopic examination, so if you’re really curious about what specific lichens you’re seeing, consider reaching out to a local naturalist group or university extension office.

The Bottom Line

Arsene’s skin lichen might not be the showstopper of your garden, but it’s one of those quiet contributors to the natural world that deserves a little appreciation. If you spot what you think might be this species on your property, consider yourself lucky – you’re witnessing a small but important part of North America’s native biodiversity in action.

While you can’t cultivate lichens like traditional garden plants, you can create conditions that welcome them by maintaining mature trees, avoiding excessive use of chemicals, and keeping some natural, undisturbed areas in your landscape. Sometimes the best gardening is simply letting nature do its thing!

Arsene’s 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 arsenei Sierk - Arsene's 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