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Botanical: Convolvulus Jalapa (LINN.)
---Habitat---The Jalap Bindweed (C. Jalapa, Linn.), but more often called Ipomea Jalapa or purga, is a native of South America and Mexico. It derives its name from Xalapa, in Mexico, where it is very abundant. It is freely grown out of doors, however, in the southern countries of Europe, and plants have been grown here in the garden of the Society of Apothecaries and also in Norfolk and Hampshire.
---Description---It is a handsome climbing convolvulaceous plant with crimson flowers and a tuberous root, which is of officinal value. The tubers, varying in size from a walnut to an orange, are dark, umber-brown in colour and much wrinkled. They are imported either whole or sliced.
---Medicinal Action and Uses---The drug Jalap is prepared from a resin which abounds in the roots. It has a slight smoky odour and the taste is unpleasant, followed by pungent acridity. It has strong cathartic and purgative action, and is used in constipation, pain and colic in the bowels and general intestinal torpor, being combined, in compound powder, with other laxatives, and with carminatives such as ginger, cloves, etc. It accelerates the action of rhubarb.
Jalap forms a safe purge for children, being given in sugar or jam to disguise the taste, and has been used thus with calomel or wormwood as a vermifuge. It proves an excellent purge in rheumatism.
---Preparations---Powdered root, 3 to 20 grains. Tincture, B.P., 1/2 to 1 drachm. Powdered resin, 2 to 5 grains. Compound powder, B.P., 1 to 2 drachms. Jalapin, 1 to 3 grains.
Other members of this Convolvulus family have economic uses. C. dissectus, an American species abounds in prussic acid, the liquor known as Noyau being prepared from it with the aid of alcohol, and the oil of Rodium, which is so attractive to rats as to cause them to swarm to it without fear, even if held in the hand of a rat-catcher, is the produce of another Convolvulus, known as C. Rhodorhiza.
One of the most important members of the order economically is C. Batatas, the tuberous-rooted Bindweed, or SWEET POTATO, the roots of which abound in starch and sugar and form a nourishing food, very valuable in the tropics, where it is largely cultivated. The roots are somewhat in shape like an oblong and ugly potato, often club-shaped, and are of a reddish colour. When cooked, they are excessively sweet, not unlike liquorice, and not attractive in appearance. They are usually of greater size and weight than ordinary potatoes.
Before the introduction of the Potato into Europe, the Sweet Potato was regularly imported as a wholesome article of diet, and was grown in Spain and Portugal, to which it had been brought from the West Indies. The Potato which Shakespeare mentions twice - in the Merry Wives of Windsor and in Troilus and Cressida - is the Sweet Potato, and not the more familiar tuber of our days.
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