Characters.—Herbaceous or shrubby vascular terrestrial plants. Stem terete, branched, leafy. Leaves inserted spirally on the stem, imbricated, simple, sessile or decurrent, never articulated. Spore cases (sporocarpia; thecae; sporangia) axillary, mostly uniform, sometimes, on the same individuals biform; some bivalved, containing a farinaceous powder, composed of polygonal smooth or papillose-spinulous granules (sporules; pollen?) others 3-4-coccous, 3-4-valved, containing a few (usually 3 or 4) somewhat globular corpuscles (spores? gemmae or buds?) marked at the vertex with a three-legged raphe.
Properties.—These are but little known.
An acrid principle resides in several species. Both Lycopodium clavatum and L. Selago act as emetics. The latter species, called muscus catharticus seu erectus, and supposed to be the Selago [Pliny, Hist. Nat. lib. xxiv. cap. 65.] of the Druids, has also been employed as a cathartic emmenagogue, and to produce abortion. In large doses it operates as a narcotico-acrid poison. A decoction of it is sometimes employed by the peasants of Sweden, and other places, as a lotion to destroy pediculi on the skin of horses, cows, pigs, &c [Murray, App. Medicam. vol. v. p. 493.]. Dr. Buchner [Repert. für d. Pharmacie, Bd. xiv. s. 311, 1823.] has recorded some cases of accidental poisoning by it, in which it caused staggering and sickness. Lycopodium catharticum, Hooker (L. rubrum, Chamisso) is also a violent purgative. Some species, e.g. Lycopodium Phlegmaria, Linn., and Selaginella convoluta, Spring (L. hygrometricum, Mart.) are reputed aphrodisiacs.
The Elements of Materia Medica and Therapeutics, Vol. II, 3th American ed., was written by Jonathan Pereira in 1853.