Club Mosses

Club Mosses, two allied groups of plants, the Lycopodiaceae and the Selaginellaceae, resembling one another in general habit but differing much in their reproductive and minute structure. Though having some resemblance to mosses, they belong to an altogether higher grade of organisation, more nearly allied to ferns. At the present day they are neither numerous nor of large size; but in Palaeozoic rocks they are represented by gigantic forms, such as Lepidodendron and Sigillaria (q.v.), which have largely contributed to the formation of coal (q.v.). The chief existing genera are Lycopodium and Selaginella, which occur over the whole globe. They have thread-like, and generally procumbent branching stems covered with overlapping minute pointed leaves, and terminating in the club-like leafy spore-bearing cone from which the popular name is derived. Lycopodium produces only one kind of sporangium and spore, and is thus isosporous; Selaginella bears two kinds, megasporangia containing four relatively large female megaspores, and microsporangia enclosing numerous small microspores, and is thus heterosporous. The megasporangia correspond to the ovules and the microspores to the pollen-grains in the higher plants. Several kinds of Selaginella are grown for the beautiful metallic lustre of their leaves, and the spores of our British Lycopodium clavatum, or stag's-horn moss, are collected in Germany to cover pills, and to make theatrical lightning and other fireworks, they being oily and readily flammable.