or CLUB-MOSS; a genus of the natural order of musci, belonging to the cryptogamia class of plants. The antherae are bivalved and fissile; there are no calyptra. There are 24 species; of which the following are the most remarkable.

1. The clavatum, or common club-moss, is common in dry and mountainous places, and in fir forests. The stalk is prostrate, brauched, and creeping, from a foot to two or three yards long; the radicles woody. The leaves are numerous, narrow, lanceolate, acute, often incurved at the extremity, terminated with a long white hair, and everywhere surround the stalk. The peduncles are erect, firm, and naked (except being thinly set with lanceolate scales), and arise from the ends of the branches. They are generally two or three inches long, and terminated with two cylindrical yellowish spikes, imbricated with oval-acute scales, finely lacerated on the edges, and ending with a hair. In the ala or bottom of the scale is a kidney-shaped capsule, which bursts with elasticity when ripe, and throws out a light yellow powder, which, blown into the flame of a candle, flashes with a small explosion. The Swedes make mats of this moss to rub their shoes upon. In Russia, and some other countries, the powder of the capsules is used in medicine to heal galls in children, chaps in the skin, and other sores. It is also used to powder over officinal pills, and to make artificial lightning at theatres. The Poles make a decoction of the plant, and, dipping a linen cloth into it, apply it to the heads of persons afflicted with the disease called the phia polonica, which is said to be cured by this kind of fomentation.

2. The selago, or fir club-moss, is common in the Highland mountains of Scotland, and in the Hebrides. The stalk at the base is single and reclining; but a little higher is divided into upright dichotomous branches, from two to six inches high, surrounded with eight longitudinal oblique series of lanceolate, smooth, rigid, imbricated leaves. Near the summits of the branches, in the ala of the leaves, are placed single kidney-shaped capsules, consisting of two valves, which open horizontally like the shells of an oyster, and LYCOPODIUM and cast out a fine yellow powder. These capsules Linnaeus supposes to be anthers, or male parts of fructification. In the axils of many of the leaves, near the tops of the branches, are often found what the same great author calls female flowers, but which the ingenious Haller esteems to be only gems or buds of a future plant. They consist, first, of four stiff, lanceolate, incurved, minute leaves, one of the outermost longer and larger than the rest. These are supposed to correspond to the calyx in regular flowers. Again, at the bottom of this calyx are five small pellucid substances resembling leaves, visible only by a microscope, which are supposed analogous to pistils. These, in time, grow up into three large broad leaves, two of the five united together like the hoof of an ox; with a third narrower one annexed at the base, and two other minute ones opposite to the other three. These five leaves are joined at the base; and in autumn, falling from the calyx, vegetate, and produce a new plant. See a dissertation De seminibus usufructu, Amstel. Academ. II. p. 261. In the island of Ragusa, near Sky, in Rossshire, and some other places, the inhabitants make use of this plant instead of alum, to fix the colours in dyeing. The Highlanders also sometimes take an infusion of it as an emetic and cathartic; but it operates violently; and, unless taken in a small dose, brings on giddiness and convulsions. Linnaeus informs us, that the Swedes use a decoction of it to destroy lice on swine and other animals.