North America Native Plant

Phaeoceros Mohrii

Botanical name: Phaeoceros mohrii

USDA symbol: PHMO14

Habit: nonvascular

Native status: Native to North America  

Synonyms: Anthoceros mohrii Austin (ANMO11)  ⚘  Aspiromitus microsporus Steph. (ASMI19)  ⚘  Phaeoceros microsporus (Steph.) Hässel (PHMI20)   

Phaeoceros mohrii: The Mysterious North American Hornwort If you’ve ever wondered about those tiny, flat green growths you sometimes spot in the shadiest, dampest corners of your garden, you might be looking at a hornwort. Meet Phaeoceros mohrii, a fascinating little plant that’s probably been quietly doing its thing in ...

Phaeoceros mohrii: The Mysterious North American Hornwort

If you’ve ever wondered about those tiny, flat green growths you sometimes spot in the shadiest, dampest corners of your garden, you might be looking at a hornwort. Meet Phaeoceros mohrii, a fascinating little plant that’s probably been quietly doing its thing in North American landscapes long before anyone thought to give it a fancy scientific name.

What Exactly Is Phaeoceros mohrii?

Phaeoceros mohrii is a hornwort – one of those ancient plant groups that makes mosses look like newcomers. Don’t let the lack of a common name fool you; this little green citizen has been around for millions of years, quietly contributing to ecosystems across North America. You might also see it referred to by its synonyms: Anthoceros mohrii, Aspiromitus microsporus, or Phaeoceros microsporus in older botanical texts.

Like all hornworts, this species is what botanists call a bryophyte – a group that includes mosses and liverworts. Think of them as the humble ground crew of the plant world, working behind the scenes to keep ecosystems healthy.

Where You’ll Find This Native Beauty

As a native North American species, Phaeoceros mohrii has earned its place in our local ecosystems. While the exact distribution details remain somewhat mysterious (hornworts don’t always get the attention they deserve from researchers), this species calls North America home and has been quietly thriving here for ages.

Is It Beneficial to Your Garden?

Here’s where things get interesting. While you probably won’t be rushing to the nursery to buy Phaeoceros mohrii, it can actually be a welcome guest in your garden ecosystem:

  • Soil health hero: Hornworts help break down organic matter and contribute to soil formation
  • Moisture indicator: Their presence tells you that area has consistent moisture and good growing conditions
  • Ecosystem support: They provide habitat for tiny soil organisms that keep your garden’s underground community thriving
  • Natural ground cover: In the right conditions, they create a living carpet that prevents soil erosion

The best part? If Phaeoceros mohrii shows up in your garden naturally, it means you’re doing something right with moisture management and creating habitat for native species.

How to Identify This Tiny Marvel

Spotting Phaeoceros mohrii requires getting down to ground level – literally. Here’s what to look for:

  • Size: These are small, flat plants that hug the ground closely
  • Shape: The plant body (called a thallus) is ribbon-like and flat, often branching
  • Color: Various shades of green, depending on growing conditions and age
  • Texture: Smooth and somewhat glossy when moist
  • Habitat: Look for them in consistently moist, shaded areas, often attached to rocks, logs, or soil

The key distinguishing feature of hornworts is their sporophytes (the spore-producing structures), which look like tiny horns sticking up from the flat plant body – hence the name hornwort.

Creating Hornwort-Friendly Conditions

You can’t exactly plant Phaeoceros mohrii from seed, but you can create conditions that welcome it and other beneficial bryophytes:

  • Maintain consistent moisture: These plants love areas that stay damp but not waterlogged
  • Provide shade: They thrive in areas with filtered light or partial shade
  • Avoid chemicals: Herbicides and fertilizers can harm these sensitive plants
  • Leave natural debris: Dead leaves and small branches provide attachment sites
  • Minimize soil disturbance: Once established, they prefer to be left alone

A Small Plant with Big Importance

While Phaeoceros mohrii might not win any garden beauty contests, it represents something valuable: the intricate web of life that makes healthy ecosystems possible. These tiny plants are indicators of environmental health and contributors to biodiversity, even if they do their work mostly out of sight.

The next time you’re in your garden, take a moment to appreciate the small wonders growing at ground level. That little flat green thing might just be Phaeoceros mohrii, a native North American hornwort that’s been perfecting the art of quiet garden citizenship for millions of years.

Phaeoceros Mohrii

Classification

Group

Hornwort

Kingdom

Plantae - Plants

Subkingdom
Superdivision
Division

Anthocerotophyta - Hornworts

Subdivision

Anthocerotae

Class

Anthocerotopsida

Subclass
Order

Anthocerotales

Family

Anthocerotaceae Dumort.

Genus

Phaeoceros Prosk. - phaeoceros

Species

Phaeoceros mohrii (Austin) Hässel

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