Botanical Origin—Lycopodium clavatum L.—This plant, the Common Clubmoss, is almost cosmopolitan. It is found on hilly pastures and heaths throughout Central and Northern Europe from the Alps and Pyrenees to the Arctic reunions, in the mountains of the east and centre of Spain, throughout Russian Asia to Amurland and Japan, in North and South America, the Falkland Isles, Australia and the Cape of Good Hope. It occurs throughout Great Britain, but is most plentiful on the moors of the northern counties.
The part of the plant employed in pharmacy is the minute spores, which, as a yellow powder, are shaken out of the kidney-shaped capsules or sporangia, growing on the inner side of the bracts covering the fruit-spike.
The manner in which those sporæ are able to reproduce the mother plant is not yet satisfactorily ascertained.[2724]
History—The Common Clubmoss was well known as Muscus terrestris or Muscus clavatus, to the older botanists, as Tragus, Dodonæus, Tabernæmontanus, Bauhin, Parkinson and Ray, by most of whom its supposed virtues as a herb have been commemorated. Though the powder (spores) was officinal in Germany, and used as an application to wounds in the middle of the 17th century,[2725] it does not appear to have been known in the English shops until a comparatively recent period. It is not included by Dale[2726] in the list of drugs sold by London druggists in 1692, nor enumerated in English drug lists of the last century; and it never had a place in the London Pharmacopœia.
Description—Lycopodium is a fine, mobile, inodorous, tasteless powder of pale yellow hue, having at 16° C. a sp. gr. of 1·062. It floats on water and is wetted with difficulty, yet sinks in that fluid after boiling. By strong titration it coheres, assumes a grey tint, and leaves an oily stain on paper; it may then be mixed with water. It is immediately moistened by oily and alcoholic liquids, chloroform, or ether. It loses only 4 per cent. of moisture when dried at 100° C. When slowly heated, it burns away quietly, but when projected into flame, it ignites instantly and explosively, burning with much light, an effect exhibited by some other pulverulent bodies having a peculiar structure, as fern spores and kamala.
Microscopic Structure—Under the microscope lycopodium is seen to be composed of uniform cells or granules, 25 mkm. in diameter, each bounded by four faces, one of which (the base) is convex, while the others terminate in a triangular pyramid, the three furrowed edges of which do not reach quite to the base. These tetrahedral granules are marked by minute ridges, forming by their intersections, regular five- or six-sided meshes. At the points of intersection, small elevations are produced, which, under a low magnifying power, give the granules a speckled appearance. Below this network lies a yellow, coherent, thin, but compact membrane, which exhibits considerable power of resistance, not being ruptured either by boiling water or by potash lye. Oil of vitriol does not act upon it in the cold, even after several days; but it instantly penetrates the grains and renders them transparent, while at the same time numerous drops of oil make their appearance and quickly exude.
Chemical Composition—One of the most remarkable constituents of lycopodium spores is a fixed oil, which they contain to the astonishing amount of 47 per cent. Bucholz pointed out its existence in 1807, but obtained it only to the extent of 6 per cent. Yet if the spores are thoroughly comminuted by prolonged trituration with sand, and are then exhausted with chloroform or ether, we find that the larger proportion above mentioned can be obtained. The oil is a bland liquid, which does not solidify even at -15° C.
By subjecting lycopodium or its extract to distillation with or without an alkali, Stenhouse obtained volatile bases, the presence of which we can fully confirm; but they occur in exceedingly small proportion. The ash of lycopodium amounts to 4 per cent.; it is not alkaline; it contains alumina, and one per cent. of phosphoric acid, constituents likewise found in the green parts of the plant.
Production and Commerce—To obtain lycopodium, the tops of the plant are cut as the spikes approach maturity, taken home, and the powder shaken out and separated by a sieve. It is collected chiefly in July and August, in Russia, Germany and Switzerland. The quantity obtained varies greatly by reason of frequent failures in the growth of the plant.
France imported in 1870, 7262 kilo. (16,017 lb.) of lycopodium, chiefly from Germany. The consumption in England is probably very much smaller, but there are no data to consult.