North America Native Plant

Rimelia Lichen

Botanical name: Rimelia simulans

USDA symbol: RISI

Habit: lichen

Native status: Native to North America  

Synonyms: Parmelia simulans Hale (PASI3)  ⚘  Parmotrema simulans (Hale) Hale (PASI6)   

Rimelia Lichen: A Fascinating Natural Addition to Your Garden’s Ecosystem If you’ve ever noticed pale, crusty patches growing on the bark of trees in your yard, you might have encountered the intriguing world of lichens. One species you may come across is the rimelia lichen (Rimelia simulans), a quiet but ...

Rimelia Lichen: A Fascinating Natural Addition to Your Garden’s Ecosystem

If you’ve ever noticed pale, crusty patches growing on the bark of trees in your yard, you might have encountered the intriguing world of lichens. One species you may come across is the rimelia lichen (Rimelia simulans), a quiet but important member of North America’s natural communities that deserves a closer look.

What Exactly is Rimelia Lichen?

Rimelia lichen isn’t actually a plant at all – it’s something much more fascinating! This organism is a symbiotic partnership between fungi and algae, working together to create those grayish-green to pale green crusty formations you see decorating tree bark and occasionally rocks. You might also see it listed under its former scientific names, Parmelia simulans or Parmotrema simulans, as lichen classification has evolved over time.

Where Does Rimelia Lichen Call Home?

This native North American species is most commonly found throughout eastern regions of the continent, thriving in temperate climates where air quality remains relatively good. It’s a natural part of our local ecosystems and has been quietly doing its job for countless years.

Is Rimelia Lichen Good for Your Garden?

While you can’t exactly plant rimelia lichen (it establishes itself naturally), having it present in your garden is actually a wonderful sign! Here’s why you should appreciate these crusty companions:

  • They’re excellent indicators of good air quality – lichens are sensitive to pollution
  • They contribute to biodiversity in your garden ecosystem
  • They provide food and shelter for tiny insects and other small creatures
  • They add natural texture and visual interest to tree bark
  • They help with nutrient cycling in forest environments

How to Identify Rimelia Lichen

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

  • Look for grayish-green to pale green crusty patches on tree bark
  • The surface appears somewhat rough and bumpy rather than smooth
  • It forms irregular patches that can vary in size
  • You’ll typically find it on the bark of deciduous trees
  • It may occasionally appear on rocks or other hard surfaces

Creating Lichen-Friendly Conditions

While you can’t plant rimelia lichen directly, you can encourage its natural establishment by maintaining a healthy garden environment:

  • Avoid using chemical pesticides and fertilizers that can harm lichens
  • Maintain good air circulation around trees
  • Keep pollution to a minimum in your garden space
  • Allow natural processes to occur without excessive intervention
  • Preserve mature trees that provide suitable growing surfaces

The Bottom Line

Rimelia lichen might not be the showstopping flower that catches everyone’s eye, but it’s a valuable and fascinating part of a healthy garden ecosystem. If you spot these crusty, pale patches on your trees, consider yourself lucky – you’re witnessing one of nature’s most successful partnerships in action. Rather than trying to remove them, celebrate their presence as a sign that your garden is supporting native biodiversity and maintaining good environmental health.

Next time you’re walking through your garden, take a moment to appreciate these quiet, unassuming organisms. They’re working hard behind the scenes to keep your local ecosystem balanced and thriving!

Rimelia Lichen

Classification

Group

Lichen

Kingdom

Fungi - Fungi

Subkingdom
Superdivision
Division

Ascomycota - Sac fungi

Subdivision
Class

Ascomycetes

Subclass
Order

Lecanorales

Family

Parmeliaceae F. Berchtold & J. Presl

Genus

Rimelia Hale & Fletcher - rimelia lichen

Species

Rimelia simulans (Hale) Hale & Fletcher - rimelia lichen

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