North America Native Plant

Trichothelium Lichen

Botanical name: Trichothelium horridulum

USDA symbol: TRHO6

Habit: lichen

Native status: Native to North America  

Trichothelium Lichen: A Mysterious Native Worth Knowing Have you ever noticed those crusty, colorful patches growing on tree bark and wondered what they were? You might have been looking at a lichen! Today, we’re diving into the fascinating world of Trichothelium horridulum, commonly known as trichothelium lichen, a native North ...

Trichothelium Lichen: A Mysterious Native Worth Knowing

Have you ever noticed those crusty, colorful patches growing on tree bark and wondered what they were? You might have been looking at a lichen! Today, we’re diving into the fascinating world of Trichothelium horridulum, commonly known as trichothelium lichen, a native North American species that’s more interesting than you might think.

What Exactly Is Trichothelium Lichen?

Let’s clear up a common misconception first – lichens aren’t plants at all! Trichothelium lichen is actually a remarkable partnership between a fungus and algae (or sometimes cyanobacteria), working together in perfect harmony. This symbiotic relationship creates what we see as a single organism growing on tree bark.

Trichothelium horridulum belongs to the crustose lichen family, meaning it forms a crust-like layer that’s tightly attached to its host surface. Think of it as nature’s living paint job on trees!

Where You’ll Find This Native Beauty

As a native North American species, trichothelium lichen has been quietly doing its thing in our ecosystems long before European settlers arrived. While specific distribution data for this particular species is limited, lichens in the Trichothelium genus are typically found growing on the bark of various tree species throughout North America.

Is Trichothelium Lichen Good for Your Garden?

Here’s where things get exciting for eco-conscious gardeners! While you can’t exactly plant trichothelium lichen like you would a flower, having it show up naturally in your landscape is actually a wonderful sign. Here’s why:

  • Air quality indicator: Lichens are incredibly sensitive to air pollution, so their presence suggests you have clean, healthy air
  • Ecosystem health: They contribute to biodiversity and provide habitat for tiny creatures
  • Natural beauty: They add unique textures and subtle colors to tree bark
  • Low maintenance: Once established, they require absolutely zero care from you

How to Identify Trichothelium Lichen

Spotting trichothelium lichen requires a keen eye, as it’s part of a large family of similar-looking species. Here are some general characteristics to look for:

  • Location: Growing directly on tree bark
  • Texture: Crusty or crust-like appearance
  • Attachment: Firmly attached to the bark surface, not easily peeled off
  • Size: Usually forms small patches or colonies

Keep in mind that definitively identifying specific lichen species often requires microscopic examination, so don’t worry if you can’t tell one crustose lichen from another – you’re in good company!

Creating a Lichen-Friendly Environment

While you can’t plant trichothelium lichen directly, you can certainly encourage lichens to colonize your garden naturally:

  • Maintain mature trees: Older trees with established bark provide ideal lichen habitat
  • Avoid chemical treatments: Skip fungicides and other harsh chemicals that can harm lichens
  • Embrace diversity: Plant a variety of native trees with different bark textures
  • Be patient: Lichen establishment takes time, sometimes years

The Bottom Line

Trichothelium lichen might not be the showiest addition to your garden, but it’s a fascinating example of nature’s ingenuity. These quiet little organisms are working behind the scenes to indicate environmental health and contribute to ecosystem diversity. Rather than trying to cultivate them, simply appreciate them when they appear naturally on your trees.

Next time you’re walking through your garden or a nearby forest, take a moment to look closely at tree bark. You might just spot some trichothelium lichen or its relatives, quietly going about their important work in the ecosystem. It’s a reminder that some of nature’s most valuable contributions come in the smallest, most overlooked packages!

Trichothelium Lichen

Classification

Group

Lichen

Kingdom

Fungi - Fungi

Subkingdom
Superdivision
Division

Ascomycota - Sac fungi

Subdivision
Class

Ascomycetes

Subclass
Order

Pyrenulales

Family

Trichotheliaceae Bittner & F. Schill.

Genus

Trichothelium Müll. Arg. - trichothelium lichen

Species

Trichothelium horridulum (Müll. Arg.) R. Sant. - trichothelium lichen

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