021. Convolvulus jalapa. Jalap bind-weed.
Synonyma. Jalapium. Pharm. Lond.
Jalappa. Pharm. Edin.
Convolvulus Jalapa, fol. difformibus cordatis angulatis oblongis lanceolatis, caule volubili, pedunculis unifloris. Lin. Syst. Veg. & Mant. 43.
Convolvulus foliis variis, pedunculis unifloris, radice tuberosa cathartica. Mill. Dict.
Mechoacanna nigricans, sive Jalapium. Park. 180.
Bryonia Mechoacanna nigricans. Bauh. Pin. 298.
Class Pentandria. Ord. Monogynia. L. Gen. Plant. 215.
Ess. Gen. Ch. Cor. campanulata, plicata. Stigmata 2. Caps. 2-locularis: loculis dispermis.
Spec. Char. C. cause volubili, foliis ovatis subcordatis obtusis obsolete repandis subtus villosis, pedunculis unifloris. Hort. Kew. vol. 1. 211.
The root is perennial, large, ponderous, abounding with a milky juice, of an irregular oval form, and blackish colour; the stalks are numerous, shrubby, slender, twirled, striated, rising above ten feet high, and twining for support round the neighbouring plants; the leaves are various, generally more or less heart-shaped, but often angular, or oblong and pointed; they are smooth, of a bright green colour, and stand alternately upon long footstalks; the flowers are produced from short branches, sending off two peduncles, each of which supports a single flower; this is large, bell-shaped, entire, plicated, externally of a reddish colour, but of a dark purple within; [The colour will no doubt vary. This plant, at Kew, produced yellowish flowers; but the plants obtained by Houston from the Spanish Well Indies answer to the description we have given.] the calyx consists of five oval leaves, these are concave, somewhat indented at their points, and of a pale green colour; the filaments are five, slender, short, and the antherae large, and yellow; the style is shorter than the stamina; the stigma is round, and the germen oval. It is a native, of South America, and flowers in August and September. [Hort. Kew.] The plant we have figured was introduced into the Royal garden at Kew in 1778, by Mons. Thouin, and under the direction of Mr. Aiton it acquired great vigour and luxuriance, extending its stalks fifteen feet in length; and, by means of slips obtained from it, two healthy young plants have since been produced: this circumstance is the more fortunate, as the parent plant lately died. Botanists have differed much respecting the officinal Jalap plant; Linnaeus following Clusius, Plunder, Tournefort, and others, first referred it to the Mirabilis, but in the second edition of his Materia Medica he adopts the opinions of Ray and Miller, in considering it a Convolvulus; and indeed after the account of this plant given by Dr. Houston, [See Linnaeus's Observ. in Mat. Med. 1772. p. 7.] we are surprised that any doubt should still remain upon this subjecl. [The London College have not referred to the Linnaean name of this plant. — Bergius found that neither the dried root of the Mirabilis Jalapa, nor of the M. longiflora, given in the dose of half a dram, produced any cathartic effects, but he says that of the M. dichotoma satis bene purgat; and as its root also bears some resemblance to the true exotic jalap, he hence infers that it is the same. However, with great deference to the learned professor, we think these reasons insufficient to warrant his conclusion, more especially as they are repugnant to established facts. We may also observe, that all the three species of the Mirabilis are in some degree purgative; but even when fostered in the warm climate of Jamaica, so congenial to their native soil, their roots, both in appearance and medicinal power, essentially differ from those of jalap.]
It is said that the root of Jalap was first brought to Europe about the year 1610, and took its name from Xalapa, a province or town in New Spain. In the shops we find this root both cut into dices, and whole, of an oval shape, solid, ponderous, blackish on the outside, but grey within, and marked with several dark veins, by the number of which, and by its hardness, heaviness, and dark colour, the goodness of the root is to be estimated. It has scarcely any smell, and very little taste, but to the tongue and to the throat manifests a flight degree of pungency. The medicinal activity of Jalap resides principally, if not wholly, in the resin, which though given in small doses, occasions violent tormina. The gummy part bears an inconsiderable proportion to the resinous, and is found to have little or no cathartic power, but as a diuretic it is extremely active.
—That Jalap is an efficacious and safe purgative daily experience must evince, but according as the root contains more or less resin, its effects must of course vary. Hoffman thought it particularly improper and unsafe to administer this medicine to children; but Dr. Cullen observes, that if Jalap "be well triturated before exhibition with a hard powder, and the crystals of tartar are the fittest for the purpose, it will operate in lesser doses than when taken by itself, and at the same time very moderately and without griping. Except when given in very large doses, I have not found it to be heating to the system; and if it be triturated with a hard sugar, it becomes, in moderate doses, a safe medicine for children, which in this form they will readily receive, as the jalap itself has very little taste." [Cullen's Mat. Med. vol. 2. p. 540.]
—Jalap, in large doses, or when joined with calomel, is recommended, as an anthelmintic and a hydragogue, and from its general efficacy in dropsies was called Panacea Hydropicorum. [Marcgrave M. M.] For the different constitutions and conditions of body in which it is more especially indicated, or its use forbidden, we may cite the opinion of Geoffroy: "Observandum tamen Jalapam non convenire in febribus acutis, neque calidis & siccis constitutionibus. In his enim, sicut caetera purgantia acria & irritantia, calorem intensum & saepe inflammatorium in visceribus accendit, parcioremque imo saepe nullam evacuationem promovet. Sed iis convenit, qui frigidae sunt temperiei & sero scatentes, speciatim in hydrope, anasarca, & cachexia." M. M. In the Pharmacopoeias, we have Jalap in the form of tincture and of extract; and the Edinburgh College direct it also in powder, with twice its weight of the crystals of tartar. The dose of the simple powder is commonly from one scruple to two; of the compound powder it may be double this quantity, which is nearly equal to 10 or 15 grains of the extract, or about two drams of the tincture.