Lythrum (Gr. gore, from the color of. the flowers in some species), a genus of herbaceous plants belonging to the natural order lythracece, generally with opposite, entire leaves, no stipules, axillary or whorled flowers; seeds many, without albumen, and enclosed in a two-celled pod. The lythrums are usually called loosestrifes, a name which they share with the lysimachias, though the two are bo-tanically very distinct. The purple loosestrife (L. salicaria, Linn.) is a native of Europe, but is to be found in some of the older states in wet meadows; it is a fine, tall, more or less downy plant, with large purple flowers. It is remarked abroad that the color of the flowers varies there from crimson to purple, and that the foliage, though usually smooth and green, becomes hoary and downy if the plant grows in dry places; its stature also is much dwarfed in consequence. It is sometimes cultivated for its beauty, blossoming in midsummer. There are several North American species.
The L. hyssopifolia, or hyssop-leaved loosestrife, with a low stem 6 to 10 in. high, numerous oblong-linear leaves, and inconspicuous pale purple flowers, is found near salt marshes on the coast of New England and New Jersey; L. alatum and L. lineare are other native species. The lythrums are easy of cultivation by sowing their seeds, or by division of the roots of the perennial species. The purple loosestrife is mucilaginous and astringent, its decoction being blackened by sulphate of iron. It may be used in diarrhoea and chronic dysentery, &e.; the dose of the powdered herb is about a drachm two or three times a day; a decoction of an ounce to the pint may be given in the dose of two fluid ounces. The petals of the flowers of L. Hunteri are used in India for dyeing. The order of lythraceae contains many plants of decided utility. The crape myrtle (Lagerstraemia Indica), a small shrubby plant with elegant crimpled petals of a rosy red color, and much admired, belongs to this order, as also the henna plant of Egypt. (See Henna.)