Below you can see both the large dead cells and small, green, live cells in a transverse section of a Sphagnum peat moss leaf.
I just finished reading a recent scientific article on peat mosses.
A. Jonathan Shaw, Cymon J. Cox, William R. Buck, Nicolas Devos, Alex M. Buchanan, Lynette Cave, Rodney Seppelt, Blanka Shaw, Juan Larraín, Richard Andrus, Johann Greilhuber and Eva M. Temsch. 2010. Newly resolved relationships in an early land plant lineage: Bryophyta class Sphagnopsida (peat mosses). American Journal of Botany 97:1511-1531.
These researchers set out to look at the relationships among the many species of Sphagnum peat mosses. Often plants or animals are initially grouped together based on their morphology (how they look on the outside). This has been the case with peat mosses too. Using DNA sequence data, these scientists determined that some species traditionally placed in the genus Sphagnum really fall outside of this group. Since they no longer lie within Sphagnum they needed some new names.
One was given a new genus name (from Sphagnum inretortum to Eosphagnum inretortum) and placed into an already established family (Ambuchananiaceae). The prefix eo- means early or primitive, thus this would be the 'early peat moss'. For the other, both a new genus and family was created for the species (from Sphagnum sericeumm to Flatbergium sericeum in the Flatbergiaceae). I looked through the paper for some insight into the etymology of this name, but I did not think they mentioned anything specific about the naming.
Both still close relatives to their abandoned Sphagnum buddies. I know that the changing of plant and animal names may seem like a pain or trivial, but understanding which species are each others closest relatives is important. For example if you have a food allergy to a particular type of plant it is important to know who its close relatives are, because you might be allergic to them too. Or we might stumble across a new chemical in a plant that could be used in a medicine. Knowing that plant's relatives may help us to find similar kinds of helpful chemicals in other plants. Just something to think about when you hear about scientists changing the names of your favorite plant or animal.
Above is a surface view of the two different types of cells in a Sphagnum leaf.