Ipomoeae Radix. Br. Orizaba Jalap Root [Mexican Scammony Root]
"Orizaba Jalap Root is the dried root of Ipomoea orizabensis, Ledanois." Br.
Orizaba Root, Male Jalap, Light, Woody, or Fusiform Jalap; Jalap stalks; Purgo Macho (Mexican).
The genus Ipomoea (Fam. Convolvulaceae) comprises about 300 species of herbs and shrubs, some being erect, others prostrate, but very many climbing. They are remarkable for their showy flowers, as in I. purpurea, the common morning glory of the garden. Many of the species produce large tuberous roots which contain a drastic purgative resin. Orizaba (also known as light or fusiform) Jalap Root has been recently introduced into the British Pharmacopoeia as a source of scammony resin. The plant yielding it (Ipomoea orizabensis) is indigenous to Mexico and produces a large, fusiform, more or less branching root attaining a length of 5 dm., yellow on its outer surface, milky-white within. The stem is cylindrical, slightly villous and climbing. The leaves are large, petiolate, cordate, acuminate and villous on the veins. The corolla is campanulate and reddish-purple. The capsule is 2-locular and one seeded.
The drug occurs in transverse slices of the root, or in pieces of irregular shape made by vertical section of these slices. The horizontal cut surface is dark from exposure, unequal from the greater shrinking in desiccation of some parts than others, and presents the extremities of numerous fibers, which are often concentrically arranged. Internally the color is grayish, and the texture, though much less compact than that of jalap, is sometimes almost ligneous.
It is officially described as follows: "In irregular, tough, or fibrous pieces of varying size and shape, but often in portions, three to five centimetres wide and two to four centimetres thick, of transverse slices of large roots. Externally greyish-black and wrinkled, internally greyish or brownish. From the transverse surface coarse fibres protrude in irregular concentric circles. Slight odor; taste faintly acrid. Yields to alcohol (90 per cent.) a resin which has the properties enumerated under 'Scammoniae Resina.'" Br.
See also under Jalap for further facts concerning these substances.
Ipomoea root has purgative properties similar to those of true jalap, but is less powerful. It is stated (J. P. C., xxiv, 166) that thirty to sixty grains (2-3.9 Gm.) are required to act effectively. It is, however, rarely employed and is official only as a source of scammony resin.