Native Plants

Anisomeridium Lichen

Anisomeridium subprostans

USDA symbol: ANSU8

North America: native

Have you ever taken a close look at the bark of trees in your yard and noticed what looks like dark, thin patches or crusts? You might be looking at anisomeridium lichen (Anisomeridium subprostans), a fascinating organism that’s probably been quietly doing its job in your landscape without you even ...

Anisomeridium Lichen: A Tiny Forest Guardian You Might Not Even Notice

Have you ever taken a close look at the bark of trees in your yard and noticed what looks like dark, thin patches or crusts? You might be looking at anisomeridium lichen (Anisomeridium subprostans), a fascinating organism that’s probably been quietly doing its job in your landscape without you even knowing it exists.

What Exactly Is Anisomeridium Lichen?

Before we dive in, let’s clear up what we’re dealing with here. Anisomeridium lichen isn’t actually a plant at all – it’s a lichen! Lichens are remarkable partnerships between fungi and algae (and sometimes cyanobacteria) that work together as a single organism. Think of it as nature’s ultimate roommate situation, where everyone benefits.

This particular lichen is native to North America and forms what scientists call a crustose growth – basically, it creates thin, dark crusts that seem to be painted directly onto tree bark. You might also see it listed under its scientific synonyms Arthopyrenia subprostans or Ditremis subprostans in older references.

Where You’ll Find This Sneaky Little Organism

Anisomeridium lichen has made itself at home across eastern North America, with a particular fondness for the southeastern United States. It’s one of those quiet residents that prefers to keep a low profile on the bark of various trees.

Is It Good for Your Garden?

Here’s the cool part – having anisomeridium lichen in your landscape is actually a great sign! Lichens are incredibly sensitive to air pollution, so their presence indicates that your local air quality is pretty decent. It’s like having a natural air quality monitor that works 24/7 for free.

While this lichen won’t add any flashy colors or dramatic visual appeal to your garden (it’s quite subtle with its dark, thin appearance), it plays an important role in the ecosystem by:

  • Contributing to biodiversity in your woodland areas
  • Serving as a natural indicator of environmental health
  • Playing a small but important role in nutrient cycling
  • Being part of the complex web of life that makes healthy forests tick

How to Identify Anisomeridium Lichen

Spotting this lichen takes a bit of detective work since it’s not exactly showy. Here’s what to look for:

  • Very thin, dark crusts on tree bark that look almost painted on
  • Typically appears as blackish or dark brown patches
  • Smooth or slightly rough texture
  • Found on the bark of various tree species
  • May have tiny, dot-like structures (these are the reproductive parts)

The best way to get a good look is with a magnifying glass – these lichens are all about the subtle details!

Can You Grow or Encourage Anisomeridium Lichen?

Here’s where things get interesting – you can’t actually plant or grow lichens the way you would with regular plants. They’re not available at your local garden center, and you can’t just sprinkle some lichen seeds around your yard.

Instead, anisomeridium lichen will show up naturally if conditions are right. The best thing you can do to encourage lichens in general is to:

  • Maintain good air quality around your property
  • Avoid using harsh chemicals or pesticides near trees
  • Keep mature trees healthy and undisturbed
  • Create habitat diversity with native trees and natural areas

The Bottom Line

Anisomeridium lichen might not be the star of your garden show, but it’s one of those supporting characters that makes the whole ecosystem work better. If you spot these dark, crusty patches on your trees, give them a little nod of appreciation – they’re telling you that your local environment is healthy enough to support these sensitive organisms.

Rather than trying to remove or discourage them, consider their presence a badge of honor for your landscape’s environmental quality. After all, not everyone gets to host these tiny environmental monitors in their backyard!

Anisomeridium subprostans is also known as...

Often we refer to plants by their common names. When shopping for plants the scientific name is the best way to positively identify the plant species you desire. But some plants have more than one name! While it doesn't happen often, nurseries might display one name while you're searching for another. Anisomeridium subprostans is also known as:

Arthopyrenia subprostans Müll. | USDA symbol: ARSU22
Ditremis subprostans | USDA symbol: DISU8

Why do some plants have more than one name? Over time plant species may be renamed for a few reasons:

  1. Botanists in different regions named the same plant without knowing it had already been classified.
  2. A species was reclassified after scientific advances in, for example, DNA analysis.
  3. Slight variations within a species are sometimes mistakenly identified as entirely new species.

Classification

Group: Lichen
Kingdom: Fungi - Fungi
Division: Ascomycota - Sac fungi
Class: Ascomycetes
Order: Dothideales
Family: Monoblastiaceae Walt. Watson
Genus: Anisomeridium (Müll. Arg.) M. Choisy - anisomeridium lichen

Species: Anisomeridium subprostans (Nyl.) R.C. Harris - anisomeridium lichen

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