Botanical Source.—This plant has a perennial rhizome, which is fibrous, producing numerous fusiform, fleshy, scaly, pendulous tubers from its crown. The stems are 2 or 3 feet high, much branched, slender, finely hairy, and tumid at the joints. The leaves are alternate, with long, leafy, hairy sheaths, ovate, lanceolate, slightly hairy underneath, and pale-green on both sides. The flowers are white, and disposed in a long, lax, spreading, terminal panicle, with long, linear, sheathing bracts, at the ramifications. The calyx is green and smooth; the corolla white, small, unequal with one of the inner segments in the form of a lip. The ovary is 3-celled and hairy. The fruit is nearly globular, with 3 obsolete angles, and the size of a small currant (L).
History, Description, and Chemical Composition.—This plant, originally from the West Indies, has been introduced into several parts of the world, in warm latitudes and moist climates, where it is extensively cultivated. It has also been raised in South Carolina and Georgia. The plant is developed by planting portions of the root-stock, which gradually increases in size, and throws out leaves, which wither when the plant is mature. Arrow-root is prepared from the root when nearly a year old. The tubers are washed, beaten in large, deep vessels to a pulp, this is well stirred in clean water, the fibrous parts being separated by hand and thrown away. The milky liquor, which holds the starch in suspension, is passed through a fine sieve, the starch allowed to subside, the supernatant clear fluid is poured off, the starch is again washed in clean water and drained, and is then dried on sheets in the sun. This constitutes West India arrow-root, of which the finest comes from the Bermudas. The crop of the root on this island in 1891, amounted to 180,000 pounds, yielding 12 per cent of arrow-root. Bermuda arrow-root is now getting very scarce, the attention of the Bermuda planters having turned toward raising early vegetables for the New York market. The island of St. Vincent, in the West Indies, is now the leading district where arrow-root from Maranta arundinacea is produced (see J. W. McDonald, Pharm. Jour. Trans., 1887, Vol. XVII, p. 1042). Arrow-root is likewise obtained from other plants, as the M. nobilis, M. Allouia, M. indica, Tussac (regarded merely as a variety of Maranta arundinacea) (L.), and Curcuma angustifolia, and C. leucorrhiza, Roxburgh, the last three furnishing the East India arrow-root.
WEST INDIA ARROW-ROOT is in the form of a light, opaque, white powder, consisting of irregular, friable grains, varying in size from that of a millet-seed to a pea. It is inodorous, nearly tasteless, and crackles when rubbed between the fingers. Musty arrow-root should never be purchased (see Prof. Wm. Procter, Jr., Amer. Jour. Pharm., 1841, Vol. XIII, p. 188). Examined by the microscope, arrowroot is found to consist of minute, pearly globules, or granules, which are spherical or ovate, and have a diameter varying from 7 to 50 micromillimeters. The rings are said to be distinct, though fine. In polarized light, very distinct crosses are seen, the junction of the arm of the cross indicating the position of the hilum.
Arrow-root presents all the chemical relations of wheat and potato-starch, though it makes a firmer jelly with the same quantity of boiling water, 9 parts in this respect being equivalent to 14 parts of common starch. According to J. W. McDonald, the tuber consists of 27 per cent starch, 63 per cent water, 1.56 per cent albumen, 4.10 per cent sugar, gum, etc., 0.26 per cent fat, 2.82 per cent fiber, and 1.23 per cent ash. Arrow-root starch, according to the same authority, contains 15.87 per cent water and 83.70 per cent starch. West India arrow-root is sometimes adulterated with wheat or potato starch, or with starches from sago and tapioca. The German Pharmacopoeia of 1872 (see C. L. Lochman's translation, 1873) recommended the test to shake 1 part of arrow-root for 10 minutes with 10 parts of a mixture consisting of 2 parts of hydrochloric acid and 1 part of water; the greater part of the powder should separate unchanged, and should not become mucilaginous nor yield an herbaceous odor similar to that of green, unripe beanpods. According to Prof. Schaer (see Amer. Jour. Pharm., 1875, p. 603), potato-starch in this process readily yields a thick, almost clear jelly, of a strong, herbaceous, bean-like odor, and may thus be easily recognized. (For the microscopical differentiation of genuine arrow-root from adulterations, see the afore-mentioned pharmacopoeial authority; also see literature on this phase of the subject in Flückiger, Pharmacognosie, 1891, p. 244.)
EAST INDIA ARROW-ROOT is chiefly prepared from plants growing throughout India, and particularly on the Malabar coast, the Curcuma angustifolia and Curcuma leucorrhiza, and to some extent from the Maranta indica; it is prepared by a process similar to that followed in the West Indies. It is commonly white, sometimes pale-yellow, less crackling between the fingers than the best West Indian kind, more frequently damaged by impurities, and composed of rather larger globules, unequal in size, egg-shaped, compressed, faintly rugous at their larger end, and with little projections attached to their sides. It is lighter than Maranta arrow-root, does not so quickly make a jelly, and is of inferior value.
Action and Medical Uses.—Arrow-root is nutritive, and is used as an agreeable, non-irritating diet in certain chronic diseases, during convalescence from fevers, in irritations of the alimentary canal, pulmonary organs, or of the urinary apparatus, and is well suited for infants to supply the place of breast-milk, or for a short time after having weaned them. It may be given in the form of jelly, variously seasoned with sugar, lemon-juice, fruit jellies, essences, or aromatics. Potato-starch is sometimes substituted for it, but it is more apt to cause acidity. Arrow-root is superior to every other kind of farinaceous food, except tapioca and tous-les-mois. Its jelly has no peculiar taste, and is less liable to become acid in the stomach, and is generally preferred by young infants to all others, except tapioca. Tous-les-mois makes a stiffer jelly. Two or 3 drachms of arrow-root may be boiled in a pint of water or milk, and seasoned as may be desired, if allowable.
Other Varieties of Arrow-root.—A product termed ZAMIA ARROW-ROOT, Florida arrowroot, Indian bread root, or Koonti, is prepared in Florida by the Seminole Indians from the rhizome of the Zamia integrifolia (see Amer. Jour. Pharm., 1898, p. 213), and a kind of arrow-root that came from Chili under the name Talcahuana arrow-root, proved to be the product of Alstroemeria ligtu. Other species of Alstroemeria also yield a starchy material which is used in South America, like arrow-root. Brazilian arrow-root is derived from Manihot utilissima (which see). Arrow-root of Tahiti is derived from Tacca oceanica; Australian arrow-root (of Queensland) is yielded by Canna edulis (see Canna). The Colocasia esculenta, Dioscorea sativa (Common yam) and fruit of the bread-fruit tree (Artocarpus incisa., have also yielded a fecula which has been substituted for true arrow-root.
King's American Dispensatory, 1898, was written by Harvey Wickes Felter, M.D., and John Uri Lloyd, Phr. M., Ph. D.