Sphagnum

sphag·num   (sfāg'nəm)    n.  Any of various pale or ashy mosses of the genus Sphagnum, the decomposed remains of which form peat. [New Latin, from Latin sphagnos, a kind of moss, from Greek, a kind of shrub.] sphag'nous adj.

sphagnum 

Main Entry: sphag·num
Pronunciation: 'sfag-n&m
Function: noun
1 : any of a large genus (Sphagnum, coextensive with the orderSphagnales) of atypical mosses that grow only in wet acid areas where their remains become compacted with other plant debris to form peat
2 : a mass of dehydrated sphagnum plantsused as a surgical dressing especially during World War I