Sphagnum

n. any of a variety of pale mosses that grow in marshy areas

Sphagnum is a genus of between 150-350 species of mosses commonly called peat moss, due to its prevalence in peat bogs. Members of this genus can hold large quantities of water inside their cells; some species can hold up to 20 times their dry weight in water, which is why peat moss is commonly sold as a soil amendment. Sphagnum and the peat formed from it do not decay readily because of the phenolic compounds embedded in the moss's cell walls. Peat moss can also acidify its surroundings by taking up cations such as calcium and magnesium and releasing hydrogen ions.
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(n.)
A genus of mosses having white leaves slightly tinged with red or green and found growing in marshy places; bog moss; peat moss.
  

Noun
1. any of various pale or ashy mosses of the genus Sphagnum whose decomposed remains form peat
(synonym) sphagnum moss, peat moss, bog moss
(hypernym) moss
(member-holonym) genus Sphagnum