Horse-Tail, or Equisetum, L. a genus of perennial plants, comprising eight species, six of which are indigenous: of these, the following are the principal:

1. The sylvaticum, or Wood-horse-tail, which grows in moist woods, shady places in the vicinity of rivers, and on boggy soils : it flowers in the months of April and May. Horses eat this plant with avidity; and, in some parts of Sweden, it is collected for the purpose of serving them as winter-food.

2. The arvense, Common, or Corn-horse-tail, growing in wet meadows and moist corn-fields. It is a most troublesome weed in pastures, and is seldom touched by cows, unless pressed by hunger, when it occasions an incurable diarrhoea : it is eaten with impunity by horses, bat is noxious to sheep. This rough grass is employed for cleaning and polishing tin vessels. According to Gleditsch, this species, as well as the fluviatile, or River-horse-tail, are of considerable service in tanning or dressing leather.

3. The palustre, Marsh-horse-tail, or Paddock-pipe, which flour-rishes in marshy and watery places; flowers in the months of June and July. It is not so strong as the preceding species, but is equally prejudicial to cows : farther, it is very troublesome in drains, within which it vegetates, and forms both stems and roots, several yards in length : thus the course of the water is interrupted, and the drains are totally obstructed. To remedy this inconvenience, the reader will consult p. 165 of this volume, the article Draining.

4. The hyemalc, Rough Horse-tail, Shave-grass, Pewterwort, or Dutch Rushes, is found in marshy, watery soils, and flowers in the months of July and August. This species is wholesome for horses, by which it is eaten ; but it is hurtful to cows, and disagreeable to sheep.' It is chiefly employed by turners and cabinet-makers, for polishing their work 3 as well as by dairymaids, for cleaning pails and other wooden utensils.