CLASS X.—DECANDRIA.
MONOGYNIA.
136. SENNA is a drug, the dried leaves of an annual plant (Cassia senna) which grows in various parts of Africa and Asia.
The stems of this plant are woody, and not unlike those of a shrub. The leaves are winged, and the leaflets oval, smooth, and pointed. The flowers, which grow in lengthened clusters, and are of pale yellow colour, are succeeded by oblong, compressed, and kidney-shaped pods.
The cultivation of senna is carried on to considerable extent in Ethiopia, Arabia, Persia, and Upper Egypt, from several of which countries it has, from time immemorial, been brought by the caravans to Alexandria, as the most convenient port whence it could be shipped or sold into Europe. From this circumstance, it is sometimes denominated Alexandrian senna. The process of stripping and drying the leaves is perfectly simple. When dried, they are of a yellowish green colour, have a faint, though not unpleasant smell, and a somewhat acrid, bitterish, and nauseous taste.
These leaves have long been in use in Eastern countries as a medicine; and their repute, though not so great as in the East, is very considerable in Europe. They are administered in various ways; and the pods have the same effect as the leaves.
A kind of senna has of late been cultivated, with success, in Italy and some of the southern parts of France.
137. The OFFICINAL CASSIA is a somewhat cylindrical pod, about an inch in diameter, and a foot or more in length, the fruit of a tree (Cassia fistula) which is cultivated in Egypt, the East and West Indies, and South America.