North America Native Plant

Pearson’s Phaeoceros

Botanical name: Phaeoceros pearsonii

USDA symbol: PHPE12

Habit: nonvascular

Native status: Native to North America  

Synonyms: Anthoceros bolanderi Steph. (ANBO3)  ⚘  Anthoceros pearsonii M. Howe (ANPE17)   

Pearson’s Phaeoceros: A Tiny Hornwort Worth Getting to Know If you’ve ever noticed tiny, horn-like structures poking up from moist soil in your garden and wondered what they were, you might have encountered Pearson’s phaeoceros (Phaeoceros pearsonii). This diminutive native plant belongs to an ancient group called hornworts—one of the ...

Rare plant alert!

Region: Conservation status by state

Status: S2S4: Status is uncertain but is somewhere between the following rankings: Imperiled: Extremely rare due to factor(s) making it especially vulnerable to extinction. Typically 6 to 20 occurrences or few remaining individuals (1,000 to 3,000) ⚘ Apparently Secure: Uncommon but not rare, and usually widespread. Possibly cause for longterm concern. Typically more than 100 occurrences in the state or more than 10,000 individuals ⚘

Pearson’s Phaeoceros: A Tiny Hornwort Worth Getting to Know

If you’ve ever noticed tiny, horn-like structures poking up from moist soil in your garden and wondered what they were, you might have encountered Pearson’s phaeoceros (Phaeoceros pearsonii). This diminutive native plant belongs to an ancient group called hornworts—one of the most primitive land plants on Earth.

What Exactly Is Pearson’s Phaeoceros?

Pearson’s phaeoceros is a hornwort, a type of bryophyte that’s been quietly thriving on our planet for over 400 million years. These fascinating little plants are neither mosses nor liverworts, but occupy their own special category in the plant kingdom. Like their bryophyte cousins, hornworts are non-vascular plants that lack true roots, stems, and leaves.

You might also see this species listed under its former scientific names, including Anthoceros bolanderi or Anthoceros pearsonii, but Phaeoceros pearsonii is the current accepted name.

Where to Find This Native Treasure

As a native species to North America, Pearson’s phaeoceros calls the western regions home, particularly California and surrounding areas. However, detailed distribution information for this specific species remains limited in scientific literature.

A Rare Find in Your Garden

Here’s something important to know: Pearson’s phaeoceros has a conservation status of S2S4, indicating it’s considered uncommon to rare in its native range. This makes any garden encounter with this little hornwort quite special! If you’re lucky enough to spot it growing naturally on your property, consider yourself a steward of something precious.

Identifying Pearson’s Phaeoceros

Spotting this tiny hornwort requires a keen eye and perhaps a magnifying glass. Here’s what to look for:

  • Small, flat, green plant body (called a thallus) growing close to the ground
  • Distinctive horn-like structures (sporophytes) that give hornworts their name
  • Preference for moist, shaded locations
  • Often found growing on bare soil, rocks, or decaying wood
  • Typically appears after periods of moisture

Is It Beneficial for Your Garden?

While Pearson’s phaeoceros won’t provide showy flowers or attract pollinators like traditional garden plants, it does offer some subtle benefits:

  • Helps prevent soil erosion in moist areas
  • Contributes to the biodiversity of your garden ecosystem
  • Indicates healthy, chemical-free soil conditions
  • Provides habitat for tiny soil organisms
  • Adds to the natural, wild character of native plant gardens

Should You Encourage It?

Given its rare status, if you discover Pearson’s phaeoceros growing naturally in your garden, the best approach is simply to leave it be. Avoid disturbing areas where you’ve spotted it, and try to maintain the moist, shaded conditions it prefers. This means:

  • Avoiding heavy foot traffic in those areas
  • Not using chemical fertilizers or pesticides nearby
  • Maintaining natural moisture levels
  • Preserving shade from trees or shrubs

The Bottom Line

Pearson’s phaeoceros might not be the star of your garden show, but it’s a fascinating glimpse into plant evolution and a sign of a healthy, diverse ecosystem. If you’re fortunate enough to have this rare hornwort sharing your space, consider it nature’s seal of approval on your gardening practices. Sometimes the smallest plants carry the biggest stories—and Pearson’s phaeoceros has been telling its tale for millions of years.

Pearson’s Phaeoceros

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 pearsonii (M. Howe) Prosk. - Pearson's phaeoceros

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