North America Native Plant

Richard’s Macromitrium Moss

Botanical name: Macromitrium richardii

USDA symbol: MARI3

Habit: nonvascular

Native status: Native to North America  

Synonyms: Macromitrium rhabdocarpum Mitt. (MARH)   

Richard’s Macromitrium Moss: A Tiny Garden Treasure Worth Knowing Meet Richard’s macromitrium moss, a charming little bryophyte that might just change how you think about the smallest residents in your garden. While most gardeners focus on showy flowers and towering trees, this native North American moss quietly goes about its ...

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 ⚘

Richard’s Macromitrium Moss: A Tiny Garden Treasure Worth Knowing

Meet Richard’s macromitrium moss, a charming little bryophyte that might just change how you think about the smallest residents in your garden. While most gardeners focus on showy flowers and towering trees, this native North American moss quietly goes about its business, creating miniature landscapes that deserve a closer look.

What Exactly Is Richard’s Macromitrium Moss?

Richard’s macromitrium moss (Macromitrium richardii) belongs to the fascinating world of bryophytes – those ancient green plants that include mosses, hornworts, and liverworts. Unlike typical garden plants, this little moss doesn’t have true roots, stems, or leaves in the traditional sense. Instead, it forms small, cushion-like colonies that attach themselves to rocks, tree bark, or decaying wood rather than growing directly in soil.

You might also encounter this species listed under its scientific synonym, Macromitrium rhabdocarpum, in older botanical references.

Where Does It Call Home?

This moss is a true North American native, with its primary range concentrated in the southeastern United States, particularly throughout the Appalachian region. It’s adapted to the humid, temperate conditions of these areas and thrives in the dappled light of forest understories.

A Word of Caution: Rarity Matters

Before you get too excited about adding this moss to your garden, there’s something important to know. Richard’s macromitrium moss has a conservation status of S2S4, indicating it’s considered uncommon to rare in parts of its range. This means if you’re lucky enough to encounter it or wish to cultivate it, you should only work with responsibly sourced material – never harvest from wild populations.

Spotting Richard’s Macromitrium Moss

Identifying this moss takes a keen eye and perhaps a magnifying glass! Here’s what to look for:

  • Small, dark green cushions or mats
  • Typically found growing on bark, rocks, or rotting wood
  • Forms compact colonies rather than spreading extensively
  • Prefers shaded, humid locations
  • Most commonly spotted in woodland environments

Garden Benefits: Small but Mighty

While Richard’s macromitrium moss might not attract butterflies or hummingbirds, it offers unique benefits to garden ecosystems:

  • Provides microhabitat for tiny insects and soil organisms
  • Helps retain moisture in shaded garden areas
  • Adds textural interest to rock gardens and naturalistic settings
  • Requires zero fertilizers or pesticides
  • Creates year-round green interest in appropriate conditions

Creating Moss-Friendly Conditions

If you’re interested in encouraging native mosses like Richard’s macromitrium in your garden, focus on creating the right environment rather than trying to plant specific species:

  • Maintain consistently moist, shaded areas
  • Provide surfaces like rocks, logs, or tree bark
  • Ensure good air circulation
  • Avoid using fertilizers in moss areas
  • Keep foot traffic to a minimum

The Bottom Line

Richard’s macromitrium moss represents the often-overlooked diversity of native plants that can enhance our gardens in subtle but meaningful ways. While you shouldn’t actively collect this rare species, learning to appreciate and identify it can deepen your connection to the native plant communities around you. If you’re lucky enough to discover it naturally occurring in your garden, consider yourself blessed with a truly special resident!

Remember, the best approach to rare native species like this moss is observation and protection rather than cultivation. Your garden can still benefit from moss-friendly practices that welcome whatever native bryophytes naturally find their way to your space.

Richard’s Macromitrium Moss

Classification

Group

Moss

Kingdom

Plantae - Plants

Subkingdom
Superdivision
Division

Bryophyta - Mosses

Subdivision

Musci

Class

Bryopsida - True mosses

Subclass

Bryidae

Order

Orthotrichales

Family

Orthotrichaceae Arn.

Genus

Macromitrium Brid. - macromitrium moss

Species

Macromitrium richardii Schwägr. - Richard's macromitrium moss

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