476 



MEDICAL BOTANY. 



Extractive, Gum, Starch, &c. The resin consists of two substances, Jalapine 

 composing nine-tenths of it, and Jalapic acid. 



Medical Properties. — Jalap is an active but safe purgative, producing co- 

 pious liquid stools, often causing nausea and sometimes vomiting, and almost 

 always griping. It is applicable to all cases where it is wished to make a 

 powerful impression on the bowels and to produce copious evacuations, and 

 is to be avoided where there is intestinal inflammation or lesions of the conti- 

 guous parts. Its hydragogue effects are much increased by combination with 

 cremor tartar. It is given alone or in combination, as well as in tincture and 

 extract. The dose of the powder is from ten to twenty grains, of the tincture 

 from a drachm to four drachms, and of the extract from ten grains to a scru- 

 ple. A very common combination is with calomel, ten grains of each. 



2. I. pandurata, Meyer. — Stem twining, sub-pubescent. Leaves cordate, or panduri- 

 form, acuminate, lobes rounded, peduncles 1 — 5-flowered; bracts small, at the base of the 

 peduncles ; flowers fasciculate ; corolla tubular, campanulate. 



Linn., (Convolvulus,) Sp. PL 219; Barton, Veg. Mat. Med. i. 249; Ra- 

 finesque, Med. Flor. i. 123 ; Meyer, (Ipomcea,) Prim. Esseq. 100 ; Lindley, 

 Med. Flor, 396. 



Fig. 213. 



I. pandurata. 



Common Names. — Wild 

 Potato; Wild Rhubarb; Wild 

 Jalap; Mechameck. 



Description. — Root perennial, 

 very large, cylindrical or fusiform, 

 sometimes as thick as the arm 

 and several feet in length, yellow- 

 ish outside, whitish and milky 

 within, much fissured, attenuated 

 above. Stem procumbent or 

 climbing, round, purplish. Leaves 

 cordate at base, broad, alternate, 

 petiolate, margin entire or undu- 

 late, sometimes panduriform, 

 smooth, dark-green above, paler 

 beneath. Flowers in fascicles of 

 two to five, on peduncles longer 

 than the petioles, axillary. Calyx 

 5-parted, unequal, ovate-obtuse, 

 two larger sepals external. Co- 

 rolla large, funnel-shaped, white, 

 with the tube purplish-red. Sta- 

 mens white, anthers oblong. Style 

 white, filiform, with a bilobate 

 stigma. Capsule oblong, 2-celled, 

 4-seeded. 



Common in all parts of the 

 United States in sandy or 

 gravelly soils, and also found 

 in Guiana and other places 

 in South America, flowering 

 from June to August. It was 

 known to the Indians, and is 

 noticed by Schcepf as Me- 

 choacana, which he says it 

 resembles in appearance and 

 properties. In the fresh 

 6tate the root has an unplea- 





