North America Native Plant

Sullivant’s Macrocoma Moss

Botanical name: Macrocoma sullivantii

USDA symbol: MASU5

Habit: nonvascular

Native status: Native to North America  

Synonyms: Macrocoma hymenostomum sensu Grout (MAHY3)  ⚘  Macromitrium sullivantii Müll. Hal. (MASU12)  ⚘  Macrocoma tenuis (Hook. & Grev.) Vitt ssp. sullivantii (Müll. Hal.) Vitt (MATES)   

Discovering Sullivant’s Macrocoma Moss: A Hidden Gem in North American Gardens If you’ve ever taken a close look at the tiny green carpets that grace shaded rocks and fallen logs in eastern North American forests, you might have encountered Sullivant’s macrocoma moss (Macrocoma sullivantii) without even knowing it. This diminutive ...

Discovering Sullivant’s Macrocoma Moss: A Hidden Gem in North American Gardens

If you’ve ever taken a close look at the tiny green carpets that grace shaded rocks and fallen logs in eastern North American forests, you might have encountered Sullivant’s macrocoma moss (Macrocoma sullivantii) without even knowing it. This diminutive native moss may not steal the show like a brilliant wildflower, but it plays a quietly important role in our natural landscapes and can add subtle beauty to the right garden setting.

What Exactly Is Sullivant’s Macrocoma Moss?

Sullivant’s macrocoma moss is a small bryophyte – that’s the fancy scientific term for the group that includes mosses, liverworts, and hornworts. Like all mosses, it’s an herbaceous plant that lacks true roots, instead anchoring itself to surfaces with tiny structures called rhizoids. This particular species has a knack for clinging to rocks, tree bark, and decaying wood rather than growing directly in soil.

Named after the American botanist William Starling Sullivant, who made significant contributions to bryology (the study of mosses) in the 1800s, this moss has also gone by several other scientific names throughout history, including Macromitrium sullivantii and Macrocoma tenuis subspecies sullivantii.

Where Does It Call Home?

This charming little moss is native to North America, with populations primarily found throughout the eastern and southeastern regions of the continent. You’re most likely to spot it in the wild across the Appalachian Mountains and surrounding areas, where it thrives in the humid, shaded conditions of deciduous and mixed forests.

Is It Beneficial for Your Garden?

While Sullivant’s macrocoma moss won’t attract butterflies or hummingbirds like flowering plants do, it offers several subtle but valuable benefits to garden ecosystems:

  • Erosion control: Its dense, cushion-like growth helps stabilize soil on slopes and around rocks
  • Moisture retention: Acts like a natural sponge, helping maintain humidity in shaded garden areas
  • Habitat creation: Provides shelter for tiny invertebrates that form the base of food webs
  • Natural aesthetics: Adds an authentic woodland feel to naturalistic garden designs

Identifying Sullivant’s Macrocoma Moss

Spotting this moss requires a keen eye, as it’s quite small and easily overlooked. Here’s what to look for:

  • Forms small, dense cushions or patches on rock surfaces and bark
  • Individual plants are tiny, typically just a few millimeters tall
  • Leaves are small and closely packed, giving the moss a velvety appearance
  • When present, spore capsules (sporophytes) emerge from the leafy shoots
  • Prefers acidic surfaces in shaded, moist environments

Perfect Garden Settings

If you’re hoping to encourage Sullivant’s macrocoma moss in your landscape, consider these ideal locations:

  • Woodland gardens: Shaded areas under trees where it can colonize naturally
  • Rock gardens: Particularly on acidic stone surfaces that stay moist
  • Stream sides: Areas with consistent moisture and dappled light
  • Naturalistic landscapes: Anywhere you want to create authentic forest floor conditions

Growing Considerations

Here’s where things get interesting – you don’t really plant mosses like Sullivant’s macrocoma moss in the traditional sense. These tiny plants are notoriously difficult to transplant and establish from scratch. Instead, your best bet is to create conditions that encourage natural colonization:

  • Maintain consistently moist, shaded conditions
  • Provide suitable surfaces like untreated wood or acidic rocks
  • Avoid chemical fertilizers and pesticides that can harm delicate moss communities
  • Be patient – moss establishment is a slow process that can take years

This moss is hardy across USDA zones 5-9, making it suitable for much of the temperate United States where it naturally occurs.

The Bottom Line

Sullivant’s macrocoma moss might not be the star of your garden show, but it’s definitely worth appreciating as part of a healthy, diverse ecosystem. Rather than trying to cultivate it directly, focus on creating the right conditions and let nature do the work. When it does appear, consider yourself lucky to host this small but important piece of North American natural heritage.

Remember, the best gardens often include these quiet, understated species that work behind the scenes to create the complex, beautiful ecosystems we love. Sometimes the smallest plants make the biggest difference!

Sullivant’s Macrocoma 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

Macrocoma (Hornsch. ex Müll. Hal.) Grout - macrocoma moss

Species

Macrocoma sullivantii (Müll. Hal.) Grout - Sullivant's macrocoma moss

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