Bryonia Mechoacanna alba C. B. Convolvulus americanus mechoacan dictus Raii.

Jalappa alba, Rhabarbarum album quibusdam. Mechoacan: the root of an American convolvulus, (Convolvulus Mechoacanna Linn.) brought chiefly from a province in Mexico of the same name, in thin transverse slices, like jalap, but larger and whiter.

This root was first introduced, about the year 1524, and continued in esteem for a con-siderable time, as a mild cathartic, of very little taste or smell, not liable to offend the stomach, of flow operation, but effectual and safe: by degrees, it gave place to jalap, which has now, among us, almost wholly superseded its use. It seems to differ from jalap only in being weaker: the resins obtained from the two roots appear to be of the same qualities, but mechoacan scarcely yields one sixth part so much as jalap does, and hence requires to be given in much larger doses to produce the same effects. The dose of the mechoacan in sub-stance is from one dram to two or more.