In certain environments the dead remains of sphagnum accumulate to form thick deposits of

Sphagnum is a genus of the Phyllum Bryophyta. It is commonly called as peat moss. A sphagnum grows in a wetland of marshes. These mosses store large amount of water. When these plants die in the wetland, the hard remains left after decomposition is a main source of soft coal reserve called as peat.

answer; both surfaces of the membrane are nonpermeable