This consists of the leaflets of Cassia Marilandica, an indigenous herbaceous perennial plant, sending up annually several erect simple stems, which rise usually three or four feet, and are furnished with pinnate leaves, and, in July and August, with handsome yellow flowers. The leaflets, which should be gathered towards the close of summer or beginning of autumn, are usually somewhat less than two inches long, from three to six lines broad, oblong lanceolate and mucronate or pointed, thin and pliable, and of a pale-green colour. They are usually kept in the shops in the form of oblong cakes, prepared by the Shakers, in which leaves, footstalks, and flowers are usually compressed together. Their odour is faint, their taste somewhat like that of senna. They yield their virtues to water and alcohol. Mr. Robert Rau, on treating the leaves in the same manner as senna, found them to yield the same crystalline matter, though in smaller proportion. (See Note in page 534.)

American senna is an efficient cathartic, having the peculiar characters of the imported senna, and, like that, much disposed to produce griping pain. it may be employed for the same purposes, but must be given in a dose one-third or one-half larger. The usual form of administration is that of infusion, which should be made in the proportion of six drachms to half a pint, of which one-half may be given for a dose. Like senna, it should be corrected by the addition of an aromatic, and saline cathartic.

Experiments, made by Mr. E. L. Perot, with a fluid extract carefully prepared from parcels of the leaves collected both in spring and autumn, would seem to prove that, in this form of preparation at least, the American senna is nearly or quite inert as a cathartic. {Am. Journ. of Pharm., xxvii. 301.) in order to test the virtues of the leaves in infusion, I had half a pint carefully prepared by Mr. Procter, with six drachms of the leaves and half a drachm of fennel-seed. This I found to operate moderately as a laxative in the dose of two fluidounces, and pretty actively as a purgative in that of four fluidounces, with the griping effects of senna. Besides, Mr. Rau has subsequently found an aqueous extract to prove cathartic in a dose equivalent to half an ounce of the leaves.