The Peat Moss Saga (Part 2)

The plant body of Sphagnum mosses are made up of two types of cells. They are composed of small chlorophyllose cells that function in photosynthesis, the process by which plants use water, air, and light to make sugars. Most types of mosses are mainly composed of these green chlorophyllose cells. Sphagnum however has many large hyaline cells that make up the plant. These cells are colorless, transparent and open to the outside environment with pores in their cell walls. These cells function as storage reservoirs for water and enable peat moss to function as a plant sponge. With these spongy cells, Sphagnum can hold up to 20 times its dry weight in water! This is the main reason that Sphagnum is the most economically important group of mosses. Due to its absorptive properties peat moss has been used historically by Native Americans in baby diapers and during World War I in bandages. Peat moss is widely used in the horticultural trade as a soil additive and to pack plants for transport.

The photograph shown above is of a Sphagnum leaf. It was taken using a compound microscope looking at the leaf surface. Keep in mind the leaf is only one cell layer thick. That is how we can easily see through the leaf. Thin chlorophyllose cells are packed between the large hyaline cells. The hyaline cells have wall thickenings that appear as bands across the cells. Also circular pores can be seen enabling water to enter the hyaline cells.