Table of Contents

• Flavoparmelia caperata (Common Greenshield Lichen)
• Physcia millegrana (Powdery Shield Lichen)
• Xanthoria parietina (Common Orange Lichen)
• Cladonia rangiferina (Reindeer Lichen)
• Evernia mesomorpha (Boreal Oakmoss)
• Observing Lichens
• Field Note Suggestion

Common Lichens of Minnesota – Field Guide

Introduction

Lichens are unique symbiotic organisms composed of fungi and algae (or cyanobacteria). They grow in diverse habitats across Minnesota—from forest bark to bare rock outcrops and even soil. Because they are sensitive to air quality, their presence often signals a healthy environment.

This guide highlights several common lichens you can spot during walks in Minnesota, especially in wooded and rocky areas.

Common Greenshield Lichen

(Flavoparmelia caperata)

Greenshield Circle - A rounded foliose colony anchored firmly to aging elm bark.

• Appearance: Pale green to yellowish-green, round, and leaf-like (foliose) with smooth lobes.
• Underside: Black with pale veins and short, root-like rhizines.
• Habitat: Found on tree bark—especially maple, oak, and birch—in areas with clean air.
• Season: Visible year-round.
• Tip: Look for large, circular patches on trunks with a greenish tint after rain.

Powdery Shield and Candleflame Lichen on branch
A mixed lichen community.

⚪ Physcia millegrana (Powdery Shield Lichen)

• Appearance: Grayish-white, forming small rosettes with powdery edges.
• Underside: Pale with fine rhizines.
• Habitat: Common on tree bark, fence posts, and sometimes rocks.
• Tip: Often found alongside mosses; its powdery texture helps distinguish it.

🟠 Xanthoria parietina (Common Orange Lichen)

• Appearance: Bright yellow-orange, leafy and lobed with a distinct citrus color.
• Habitat: On rocks, bark, or metal surfaces—especially in sunny areas.
• Tip: Thrives near roads or towns since it tolerates nitrogen pollution.

🩶 Cladonia rangiferina (Reindeer Lichen)

• Appearance: Bushy, pale gray-green with branching coral-like structures.
• Habitat: Ground-dwelling in sandy soils, pine forests, and bogs.
• Tip: Commonly forms mats; deer and caribou feed on it in northern regions.

🪶 Evernia mesomorpha (Boreal Oakmoss)

• Appearance: Pale green, shrubby, and branched; soft and pliable when moist.
• Habitat: On coniferous trees and birches in northern Minnesota.
• Tip: Has a sweet, earthy fragrance—used in natural perfumes.

🔍 Observing Lichens

• Look up and down: Lichens grow from ground level to tree canopies.
• After rain: Colors are richer and textures more visible.
• Tools: A hand lens (10× magnification) reveals intricate details.
• Leave them be: Lichens grow very slowly—some just a few millimeters per year.

📸 Field Note Suggestion

When you find a lichen, record:

• Date and location (GPS if possible)
• Habitat type (bark, rock, soil)
• Color, shape, and size
• A clear close-up photo for later ID

💡 Fun Fact

Minnesota’s North Shore and Boundary Waters host over 500 lichen species, including rare arctic types thriving on exposed granite.

🧭 Tip: Look for these lichens after a light rain—they’ll be at their brightest.

Happy lichen hunting! 🌲

Compiled by Ray Fraley, 2025.