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The Sphagnaceae consists of a single genus, Sphagnum with 5
species in Tasmania. Being a genus of ecological and economic
importance, a specialized branch in bryology, sphagnology, is
devoted to its study. The genus is nowhere as abundant in the
southern hemisphere as it is in the northern. In Tasmania, they are
common only in high altitude bogs. The Sphagnaceae are truly in a
class of their own. No moss genus is as immediately recognizable
and yet have species as hard to delimit as in Sphagnum.
At the stem apex, the branches in almost all cases (except
perhaps S. fuscovinosum) are tightly packed together to from
a compact head called the capitulum. Further down the stem, the
branches are arranged in fascicles (bunches) and are usually longer
and pendant.
More characteristically, the leaves of all
Sphagnum consist of two cell types: narrow chlorophyllous ones
alternating with much wider empty hyaline cells strengthened by
bar-like thickenings called fibrils.
The capsules are dark and globular and unlike most other mosses
(excepting Andreaea), borne on a thick white stalk called a
pseudopodium. Spores are dispersed in an explosive manner when the
pressure builds up in a mature capsules and blows the lid off.
In the Tasmanian species, stem morphology can often be good
taxonomic characters.
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