SPIRÆA, in botany, a genus of the pentagynia order, belonging to the icofandria class of plants.—There are 12 species; of which the most remarkable are, 1. The salicifolia, or common spiræa frutex, rises with several shrubby stalks, to the height of six or eight feet. The branches are terminated by spikes of pale flowers, the lower parts of the spikes are branched out into small spikes, but the upper parts are close and obtuse. When the flowers are past, the germens changes to pointed capsules; but they seldom come to perfection. 2. The filipendula, or common dropwort, grows in mountainous pastures in several parts of England and Scotland. It rises about a foot and an half high, with an erect stalk, and but few leaves upon it; terminated with a loose umbel of white flowers often tinged with red. 3. The ulmaria, or meadow-sweet; grows naturally on the sides of waters, and in low moist meadows, in most of the northern counties of Europe. The stalks are angular, red, and rise three or four feet high; garnished with winged leaves, and terminated by large loose bunches of white flowers.—The first species is propagated by suckers, which are sent forth in plenty from the roots of the old stems, or by laying down the tender branches. The second and third species are not cultivated. However, the tuberous pea-like roots of the second, dried and reduced to powder, make a kind of bread which in times of scarcity is not to be despised. Hogs are very fond of these roots. Cows, goats, sheep, and swine, eat the plant; but horses refuse it. The flowers of the ulmaria have a fragrant scent, which rises in distillation. The whole plant indeed is extremely fragrant, so that the common people of Sweden strew their floors with it on holidays. It has also an astringent quality, and thus has been found useful in dysenteries, ruptures, and in tanning of leather. Goats are extremely fond of it; cows and horses refuse it.