North America Native Plant

Merrill’s Beard Lichen

Botanical name: Usnea merrillii

USDA symbol: USME

Habit: lichen

Native status: Native to North America  

Merrill’s Beard Lichen: A Mysterious Air Quality Indicator in Your Garden Have you ever noticed strange, grayish-green stringy growths hanging from tree branches and wondered what on earth they could be? You might be looking at a fascinating organism called Merrill’s beard lichen (Usnea merrillii), a remarkable species that’s actually ...

Merrill’s Beard Lichen: A Mysterious Air Quality Indicator in Your Garden

Have you ever noticed strange, grayish-green stringy growths hanging from tree branches and wondered what on earth they could be? You might be looking at a fascinating organism called Merrill’s beard lichen (Usnea merrillii), a remarkable species that’s actually doing some pretty amazing things for your local ecosystem – even though you can’t plant it yourself!

What Exactly Is Merrill’s Beard Lichen?

First things first – let’s clear up what we’re dealing with here. Despite its name suggesting it’s a plant, Merrill’s beard lichen isn’t a plant at all! It’s actually a lichen, which is a fascinating partnership between a fungus and algae (or sometimes cyanobacteria) living together in perfect harmony. Think of it as nature’s ultimate roommate situation – the fungus provides structure and protection, while the algae whips up food through photosynthesis.

This particular species, scientifically known as Usnea merrillii, is native to North America and belongs to the beard lichen group, so named because of their distinctive stringy, beard-like appearance.

Where You’ll Find This Curious Organism

Merrill’s beard lichen is a native North American species, though specific details about its exact geographic distribution are not well-documented in readily available sources. Like other members of the Usnea family, it likely occurs across various regions where suitable host trees and environmental conditions exist.

How to Spot Merrill’s Beard Lichen

Identifying this lichen is all about knowing what to look for:

  • Look up! It grows as an epiphyte, meaning it lives on other plants (usually tree branches) without harming them
  • Color: Grayish-green to pale green, sometimes with a slightly yellowish tint
  • Shape: Long, stringy, branching structures that hang down like a scraggly beard
  • Texture: Appears somewhat fuzzy or hair-like from a distance
  • Location: Most commonly found hanging from deciduous and coniferous tree branches

Is It Beneficial to Have Around Your Garden?

Absolutely! While you can’t plant Merrill’s beard lichen yourself, finding it naturally occurring in your garden area is actually fantastic news. Here’s why:

Air Quality Superhero: Lichens are incredibly sensitive to air pollution, particularly sulfur dioxide. If you spot beard lichens thriving in your area, it’s a great sign that your local air quality is relatively clean. They’re like nature’s pollution detectors!

Ecosystem Support: While lichens don’t produce flowers for pollinators, they do provide food and nesting material for various wildlife species, including birds and small mammals.

Soil Building: When pieces fall to the ground and decompose, they contribute organic matter to the soil, slowly enriching your garden’s foundation.

Why You Can’t (And Shouldn’t Try to) Grow It

Here’s the thing about lichens – they’re not something you can just pop into a pot and nurture. These remarkable organisms:

  • Grow incredibly slowly (we’re talking millimeters per year)
  • Have very specific environmental requirements that are nearly impossible to replicate artificially
  • Need exactly the right balance of humidity, air quality, and host tree conditions
  • Don’t respond well to being moved or transplanted

Instead of trying to cultivate lichens, the best approach is to create conditions that naturally encourage their presence by maintaining healthy trees and good air quality in your area.

Creating a Lichen-Friendly Environment

While you can’t plant Merrill’s beard lichen directly, you can encourage conditions that might naturally support lichen communities:

  • Plant and maintain diverse native trees, especially older specimens
  • Avoid using pesticides and chemicals that could affect air quality
  • Support local air quality initiatives
  • Leave dead branches (when safe to do so) as potential lichen habitat
  • Maintain good garden biodiversity to support overall ecosystem health

The Bottom Line

Merrill’s beard lichen might not be something you can add to your shopping list at the garden center, but discovering it naturally occurring in your outdoor spaces is like finding a hidden treasure. It tells you that your local environment is healthy enough to support these sensitive organisms, and that’s something to celebrate!

So next time you’re wandering through your garden or local natural areas, take a moment to look up into the trees. You might just spot some of these fascinating beard-like growths quietly going about their business of cleaning the air and supporting the ecosystem – no planting required!

Merrill’s Beard 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

Usnea Dill. ex Adans. - beard lichen

Species

Usnea merrillii Mot. - Merrill's beard lichen

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