Origin. - The spores of Lycopodium clavatum L. and of other species of lycopodium, low-creeping perennials found in dry woods, distributed over the greater portion of the globe.

Description and Properties. - A fine powder, pale yellowish, very mobile, inodorous, tasteless, floating upon water and not wetted by it, but sinking upon being boiled with it, and burning quickly when thrown into a flame. Under the microscope the spores are seen to be sphero-tetrahedral, the sufaces marked with reticulated ridges, and the edges beset with short projections. Lycopodium contains a fixed oil and a minute quantity of a volatile base, methylamine.

Used principally externally.

Physiological Action and Therapeutics. - Lycopodium is an admirable protective, and possesses great power of absorbing oils. Its lightness, dryness, and absorptive power render it an excellent dusting-powder for excoriated surfaces, eczema, herpes, intertrigo erysipelas, superficial ulcers, etc.

Its peculiar property of not being wetted with water makes it a valuable protective to prevent irritation or chafing caused by the urine or alvine dejections of infants.

The drug is used as a basis for insufflations and in pharmacy to prevent the adhesion of pills.