14 MEDICAL BOTANY. 
the jalap plant under the name of I. purga. Dr. Christison states that the specimens derived from Dr. Wood’ 
do not exactly coincide with the plates of I. purga, as figured by Hayne, or I. Schtedeana of Nees. 
Med. Bot.) There have now been determined to be several species in Mexico affording varieties of 
Continental European botanists may have hit upon some of these, which will account for discrepancy. 
The name Ipomeea jalapa has been objected to, as preoccupied by Pursh in his Flor. Americe Septentionalis, but 
as this author was describing the plant of Michaux and under an error, in fact changing the name in compliance with 
this error, there seems to be no impropriety in giving it the correct application by its present adoption. 
Jalap appears solely to be a native of Mexico, where it thrives in an elevated region, about 6000 feet above the 
level of the sea. The root is gathered at all seasons, but particularly in March and April, when the young shoots 
begin to sprout. It takesits name from Jalapa, which city is the depot for the drug, whence it is carried to Vera Cruz, 
and exported. It has been proposed to introduce and cultivate it, for medicinal purposes, in the United States, but 
no effort so far has been successfully made. 
Jalap root comes into the market in bags, weighing from one to two hundred pounds. Sometimes large quanti- 
ties of small, light, immature tubers are sent. A full sized tuber should weigh from one to six ounces. They are 
either round, egg-shaped, or irregularly pyriform, of a mottled black and brown colour externally, fawn-coloured inter- 
nally, breaking under the hammer, and presenting an undulated resinous and starchy appearance. The odour of 
jalap is unpleasant, and the taste acrid and nauseous. 
Jalap contains starch, resin and extractive. From the resin a peculiar substance has been obtained called 
jalapine. 
Worms prey upon jalap, and by eating out the starch, leaving the resin, make it more active. 
The male jalap, a large sized light and little resinous tuber, is derived from JI. orizabensis. (Pelletan.) 
Piate LXI.—Represents the plant in Slower, the section of the corolla, and the germ and root. 
S plants, 
(See Griffith's 
jalap, and the 
CONVOLVULUS SCAMMONIA. 
LINNAEUS. 
SCAMMONY PLANT. 
ConvoivuLus Syriacus.——Morrison. 
Sex. Syst.—Pentandria, Monogynia. 
| Gen. Cuar.—Sepals five. 
Ovary two-celled, four-seeded. 
Specir. Cuar.— Root peren 
nual, branching, slender, round, smooth, twining, 
coloured at the edge. 
in length. Stamens erect, converging, thrice 
nto the market; inferior quantities, or rather, such as are made by the admixture 
stone stitute the commercial article, 
The virgin scammony 
externally; the fracture is ee: lumps, apparently fragments of larger masses, as if rubbed, and of a whitish ash colour 
choidal, and when recent, displays a glistening resinous lustre, pale green in the i 
