The gametophytes of these mosses are quite large and highly branched.  The vertical main stem has many branches crowded at the top of the stem.  The leaves have large clear water storage cells.

The sporophytes is elevated on a short side branch of the gametophyte. It consists of a round capsule with an perculum that is pushed off by pressure building up inside the drying capsule.

Spagnum mosses may grow in small patches in moist forests and in peat bogs where there are large colonies of it.