The sum expended for the importation of this drug is said to exceed 200,000_l._ per annum, a great proportion of which, it is presumed, might be saved to the country by cultivation of the plants in Great Britain. This was first attempted, about sixty years ago, by Dr. Hope, in the botanic garden at Edinburgh, and with such success as to prove that the climate even of Scotland would be no obstacle to its increase. In 1791, Sir William Fordyce received from the Society for Encouragement of Arts, Manufactures, and Commerce, a gold medal, for having raised more than 300 plants of the true rhubarb from seed. And, in 1783, Mr. Davis, of Minehead, in Somersetshire, brought to perfection as many plants as yielded three hundred pounds' weight of dried rhubarb. Since this period, rhubarb has been grown, in different parts of England, to great extent; and has so far flourished, that some of the roots have weighed seventy pounds and upwards. The principal difficulty has attended the curing of it; but this, after numerous experiments, has at length been performed in such manner, that the English drug has been found equal, or nearly equal, to that which is imported from Turkey and China. The _bark_ of rhubarb has been used for tinctures, and found, in every respect, as efficacious as the best part of the roots: and the _seeds_ possess nearly the same qualities. The _leaves_ impart an agreeable acidity, somewhat similar to that of sorrel; and a marmalade, which may, with advantage, be adopted for children, is made from the fresh _stalks_, by stripping off the bark, and boiling the pulp with an equal quantity of sugar. 135. _The COMMON RHUBARB_ (Rheum rhaponticum), _is a plant which is cultivated in kitchen gardens, and has large, blunt and smooth leaves, and the leaf-stalks furrowed on the upper side, and rounded at the edge._ This species of rhubarb grows wild on the mountains of Rhodope, in Thrace, whence it was first propagated in other parts of Europe, about the year 1630. It is chiefly in request for the _footstalks of the leaves_, which are used, (in the early part of the year, when there is little fruit) for pies and tarts. The _root_ has some of the qualities of the true rhubarb, and has occasionally been imposed upon purchasers for that drug. ---- 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._