Sphagnum is a genus of between 150-350 species of mosses commonly called peat moss, due to its prevalence in peat bogs and mires. Bogs are dependent on precipitation as their main source of water and nutrients, thus making them a favourable habitat for sphagnum as it can retain water quite well. 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.… (More on Sphagnum)