Sphagnum

Sphagnum is a genus of mosses in the family Sphagnaceae, commonly known as peat moss. There are about 380 to 500 species, found mainly in cool temperate and boreal regions. Sphagnum is a dominant component of many peatlands, particularly bogs, where it forms extensive mats that regulate water balance and soil acidity and play a key role in peat formation.

Morphology and biology: Sphagnum consists of leafy stems with leaves only a few cells thick. It contains large, dead water-storage cells called hyaline cells that can hold substantial amounts of water, giving the moss its sponge-like texture. Living photosynthetic cells lie among these tissues. Reproduction occurs by spores produced in a sporophyte, as in other mosses, but many species also spread vegetatively by fragmentation.

Ecology and peat formation: In waterlogged, acidic environments, decomposition is slowed, and Sphagnum actively acidifies its surroundings by releasing organic acids and cations. This creates and sustains bog conditions, enabling continuous peat accumulation that can sequester carbon for millennia. Sphagnum also contributes to the hydrology of peatlands by retaining water and influencing plant communities.

Uses and conservation: Historically, peat harvested from Sphagnum-dominated bogs has been used as fuel and, more widely, as a horticultural growing medium. Harvesting and drainage can release stored carbon and damage bog ecosystems, leading to habitat loss and biodiversity decline. Conservation goals focus on bog restoration and rewetting, sometimes including reintroduction or transplantation of Sphagnum to degraded sites, to restore peat formation and carbon storage.

Taxonomy and systematics: Sphagnum is the sole genus in Sphagnaceae, order Sphagnales. It is often treated as one of the earliest diverging lineages among bryophytes, with a fossil record dating to the Cretaceous.