sphagnum

noun

sphag·​num ˈsfag-nəm 

variants or sphagnum moss

1

plural sphagnums or sphagnum mosses also sphagnum : any of a genus (Sphagnum of the order Sphagnales) of mosses that grow in wet acidic areas (such as bogs or swamps) where their remains become compacted with other plant debris to form peat (see peat entry 1 sense 1a)

Peatlands develop where the ground is water-soaked throughout the growing season, causing the sphagnum to grow faster than its dead remains can decompose.

—Robert H. Mohlenbrock

We pitched our tents on sphagnum moss under towering western hemlocks …

—Ted Williams

—often used before another noun

sphagnum peat moss

Eventually the sphagnum mat becomes strong enough to support evergreens.

—Deborah Cramer

2

: a mass of sphagnum plants especially when dried

… add a thin layer of coarse sphagnum moss to stop any growing mix from trickling down into the drainage area.

—John Hopkins

Illustration of sphagnum

• sphagnum 1

Examples of sphagnum in a Sentence

Recent Examples on the Web

It's also used in air layering, a propagation method in which bundles of wet sphagnum moss are fastened around a cut in a mature plant's stem to allow for new root growth. —Alexandra Jones, The Spruce, 26 Feb. 2026

Moisten some sphagnum moss and wrap it around the wound, then cover the moss with plastic wrap to lock moisture in. —Karen Brewer Grossman, Southern Living, 1 Jan. 2026

Chief among them are the bog makers themselves, the peat mosses or sphagnum, whose bodies become antiseptic bandages when called upon. —Literary Hub, 2 June 2025

Step 2: Prepare Moss Prepare a shallow bed of perlite or sphagnum moss. —Derek Carwood, Better Homes & Gardens, 18 Feb. 2025

The research team turned to sphagnum peat bogs in the northeastern U.S., environments rich with competitive microbial species. —Tom Howarth, Newsweek, 3 Dec. 2024

Word History

Etymology

New Latin, from Latin sphagnos, a moss, from Greek

First Known Use

1741, in the meaning defined at sense 1

Kids Definition

sphagnum

noun

sphag·​num ˈsfag-nəm 

1

: any of a large genus of mosses that usually grow in wet areas (as bogs) and become compacted with other plant matter to form peat

2

: a mass of sphagnum plants

Medical Definition

sphagnum

noun

sphag·​num ˈsfag-nəm 

variants or sphagnum moss

1

: any of a genus (Sphagnum of the order Sphagnales) of mosses that grow in wet acidic areas where their remains become compacted with other plant debris to form peat

2

: a mass of dehydrated sphagnum plants used as a surgical dressing especially during World War I