North America Native Plant

Polycoccum Lichen

Botanical name: Polycoccum squamarioides

USDA symbol: POSQ2

Habit: lichen

Native status: Native to North America  

Synonyms: Polycoccum epicrassum (H. Olivier) R. Sant. (POEP4)   

Polycoccum Lichen: The Tiny Garden Detective You Never Knew You Had Meet Polycoccum squamarioides, commonly known as polycoccum lichen – a fascinating little organism that’s probably living in your garden right now, even if you’ve never noticed it. This isn’t your typical garden plant, and that’s exactly what makes it ...

Polycoccum Lichen: The Tiny Garden Detective You Never Knew You Had

Meet Polycoccum squamarioides, commonly known as polycoccum lichen – a fascinating little organism that’s probably living in your garden right now, even if you’ve never noticed it. This isn’t your typical garden plant, and that’s exactly what makes it so intriguing!

What Exactly Is Polycoccum Lichen?

Before we dive in, let’s clear up what we’re dealing with here. Polycoccum lichen isn’t actually a plant at all – it’s a lichen, which is a remarkable partnership between a fungus and an algae living together in perfect harmony. Think of it as nature’s ultimate roommate situation, where both parties benefit from the arrangement.

This particular lichen is what scientists call a lichenicolous fungus, which is a fancy way of saying it’s a lichen that lives on other lichens. It’s like the friend who crashes on your couch – but in this case, everyone’s happy with the arrangement!

Where You’ll Find This Tiny Marvel

Polycoccum squamarioides is native to North America, where it quietly goes about its business in temperate regions across the continent. You won’t find it growing alone, though – it’s always found as a guest on other lichen species, particularly those with leafy, scale-like structures.

Spotting Polycoccum Lichen in Your Garden

Here’s where things get interesting for the observant gardener. Polycoccum lichen appears as tiny, dark dots or bumps on the surface of its host lichens. These little black specks might look like dirt or damage at first glance, but they’re actually the fruiting bodies of this fascinating organism.

To identify polycoccum lichen, look for:

  • Small, black, dot-like structures on other lichens
  • Round to oval-shaped fruiting bodies
  • A parasitic relationship with leafy or crusty lichens
  • Presence on tree bark, rocks, or soil where host lichens grow

Is Polycoccum Lichen Beneficial for Your Garden?

While you can’t exactly plant polycoccum lichen (more on that in a moment), its presence is actually a wonderful sign for your garden ecosystem. Lichens in general are excellent indicators of air quality – they’re like tiny environmental watchdogs that can’t tolerate pollution.

If you spot polycoccum lichen and its hosts thriving in your space, pat yourself on the back! It means your garden has:

  • Good air quality
  • A healthy, balanced ecosystem
  • Minimal chemical pollution
  • The right moisture conditions for diverse life forms

The Truth About Growing Polycoccum Lichen

Here’s where we need to have a heart-to-heart: you can’t actually plant or cultivate polycoccum lichen like you would a tomato or a rose bush. This little organism has very specific needs and shows up when conditions are just right – kind of like that perfect sunset that you can’t schedule but can definitely appreciate when it happens.

Polycoccum lichen requires:

  • Clean, unpolluted air
  • The presence of suitable host lichens
  • Proper moisture levels (not too wet, not too dry)
  • Time – sometimes lots of it – to establish naturally

Creating Lichen-Friendly Conditions

While you can’t plant polycoccum lichen directly, you can certainly create an environment where it might choose to make an appearance. Think of yourself as a lichen landlord, creating the perfect conditions for these tiny tenants:

  • Avoid using chemical pesticides and fertilizers near trees and rocks
  • Maintain good air circulation in your garden
  • Leave some wild, undisturbed areas where lichens can establish
  • Resist the urge to clean every surface – those crusty patches on rocks and tree bark might be lichen homes
  • Be patient – lichen communities develop slowly over time

The Bottom Line

Polycoccum lichen may not be the showstopper that draws visitors to your garden, but it’s a quiet indicator that you’re doing something right. Its presence suggests that your outdoor space is healthy, balanced, and welcoming to diverse forms of life.

So the next time you’re wandering through your garden, take a moment to look closely at the bark of your trees or the surfaces of rocks. Those tiny black dots might just be polycoccum lichen, silently testifying to the health of your little corner of the world. And honestly, what could be more rewarding than knowing your garden is so healthy that even the pickiest of nature’s partnerships wants to call it home?

Polycoccum Lichen

Classification

Group

Lichen

Kingdom

Fungi - Fungi

Subkingdom
Superdivision
Division

Ascomycota - Sac fungi

Subdivision
Class

Ascomycetes

Subclass
Order

Dothideales

Family

Dacampiaceae Körb.

Genus

Polycoccum Sauter ex Krober - polycoccum lichen

Species

Polycoccum squamarioides (Mudd) Arnold - polycoccum lichen

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