ALYSON, or ALYSOIDES, Madwort; (from αλυσος, to be mad; because it was believed to have the property of curing madness): A genus of the filiculosa order, belonging to the tetradyamia clas of plants; and, in the natural method, ranking under the 39th order, Silifquosa. The characters are: The calyx is an oblong four-leaved perianthium: The corolla consists of four cruciform petals; with claws the length of the calyx, the petals shorter: The stamens consist of six filaments, the length of the calyx, two of them rather shorter and denticulated; the antherae are erect and expanding: The pistillum has an ovate germen; the stylos is simple, and the length of the stamens; the stigma is obtuse: The pericarpium is a sub-globular emarginated filicle, furnished with a bilocular stylos, having an elliptic partition: The seeds are few, orbicular, and affixed to filiform receptacles.

Species. Of this genus, Linnaeus enumerates 19 species; but none of them are remarkable either for beauty, or any other property, except the halimifolium, or madwort with whole spear-shaped leaves. This spreads itself upon the ground, and never rises to any height. It produces, at the extremity of its branches, very pretty tufts of small white flowers; of which it is seldom deflatured for six or seven months successively; for which reason it well deserves a place in the gardens of the curious.

Culture. Though these plants are natives of the southern parts of Europe; yet, if planted on a dry, lean, or rubbishy soil, they will endure our severest winters in the open air.—The halimifolium seldom continues above two or three years, and must therefore be often sown to preserve it; or if the seeds are suffered to fall, the plants will rise without any trouble. It may also be propagated by cuttings, which ought to be planted in April or May, and are very apt to take root, if kept shaded in the heat of the day, and gently refreshed with water.

This plant, as already observed, was thought to cure some kinds of madness; but the present practice has entirely rejected it for this or any other purpose.