Horse-tail; a genus of the order of filices, belonging to the cryptogamia class of plants. There are seven species, of which the most remarkable are, 1. The sylvaticum, or wood horse-tail. It grows in woods and moist shady places in many parts of England and Scotland. The stalk rises from 12 to 18 inches high, angular, and rough to the touch; the angles being edged with sharp spicules, scarcely visible without a microscope. The leaves grow verticillate, 12 or more in a whorl, and these whorls are about an inch distant from one another. The leaves are very slender, nearly quadrangular, about five inches long, pendent, and beset with several other secondary whorls, so that it resembles a pine-tree in miniature. Horses are very fond of this plant, and in some parts of Sweden it is collected to serve them as winter food. 2. The arvense, common or corn horse-tail, grows in wet meadows and corn-fields. The most remarkable property of this is, that its seeds, when viewed by a microscope, are seen to leap about as if they were animated. It has a very astringent and diuretic quality, and has been esteemed serviceable in the hematuria and gonorrhea, but is disregarded by the present practice. It is a troublesome plant in pastures; and disagreeable to cows, being never touched by them unless they are compelled by hunger, and then it brings on an incurable diarrhoea. It does not seem to affect horses or sheep. 3. The palustre, marsh horse-tail, or paddock pipe, is frequent in marshes and ditches. It is not so rough as the former, but is likewise prejudicial to cattle. 4. The fluvatile, or great river horse-tail is frequent in shady marshes. marshes, and on the brink of stagnant waters. It is the largest of all the species, growing sometimes to the height of a yard, and near an inch in diameter. Hal-ler tells us, that this kind of equisetum was eaten by the Romans; and Linnaeus affirms, that oxen and rein-deer are fond of it, but that horses refuse it.

The hyemale, rough horse-tail, shave-grass, or Dutch rushes. This is much used by the whitemiths and cabinet-makers, under the name of Dutch rushes, for polishing their metals and wood. All the other species will answer this purpose in some degree, but the last better than any of the rest. In Northumberland the dairy-maids scour and clean their milk-pails with it. Some imagine, that if cows are fed with this species, their teeth will fall out.