Jalap Plant (Exogonium) - A graceful perennial trailing plant, none more beautiful among climbing plants than E. purga, and of its hardiness there can be little doubt.
Several members of the order are used medicinally for the strong purging properties of the milky juice (latex) which they contain; scammony is the dried latex from the underground stem of Convolvulus Scarnmonia, a native of the Levant, while jalap is the product of the tubercles of Exogonium Purga, a native of Mexico.
This kind of jalap, the Purga de Sierra Gorda of the Mexicans, was traced by Hanbury to I pomaea simulans.