71. Tacca, Forster.
Sex. Syst. Hexandria, Monogynia.
This genus contains two species, which deserve a short notice.
1. Tacca pinnatifida, Roxb. Fl. Ind. ii. 172.—A native of the Moluccas and Malay countries. The tuberous roots are intensely bitter when raw, but yield a large quantity of beautifully white starch, used for puddings, cakes, and other articles of confectionery. The tubers "are the tacca youy of some navigators; they form an article of diet in China and Cochin China, as also in Travancore," where, according to Dr. Ainslie, they attain a large size, and are eaten by the natives, with some acid, to subdue their acrimony. [Royle, Illustrations of the Botany of the Himalayan Mountains, p. 379.]
2. Tacca oceanica, Nuttal, Amer. Journ. of Pharm, vol. ix. p. 306.—A native of Tahiti, and other islands of the South Sea. Until Mr. Nuttal pointed out its peculiarities, it was supposed to be identical with T. pinnatifida. Ellis [Polynesian Researches, vol. i. p. 361, 1829.] says that the "pia, or arrow-root, chailea tacca" grows on the high sandy banks near the sea, or on the sides of the lower mountains.
The tuberous roots yield a highly nutritious fecula. At Tahiti (Otaheite), this fecula is procured by washing the tubers, scraping off their outer skin, and then reducing them to a pulp by friction on a kind of rasp made by winding coarse twine (formed of the cocoa-nut fibre) regularly round a board. [Ellis states that the rind of the root is scraped off by a courie shell, and the root then grated on a piece of coral.] The pulp is washed with sea-water through a sieve, made of the fibrous web which protects the young frond of the cocoa-nut palm. The strained liquor is received in a wooden trough, in which the fecula is deposited; and the supernatant liquor being poured off, the sediment is formed into balls, which are dried in the sun for 12 or 24 hours, then broken and reduced to powder, which is spread out in the sun to dry. [Matthews, Gardener's Magazine, vol. viii. p. 585, Lond. 1832.]
Tacca starch, or Tahiti arrow-root, sometimes called Otaheite salep, [Rees's Cyclopaedia, art. Tacca pinnatifida.] is imported into London, and sold as "Arrow-root, prepared by the native converts at the Missionary stations in the South Sea Islands." It is a white amylaceous powder, with a slightly musty odour. Examined by the microscope, I find it to consist of particles [The following measurements, in parts of an English Inch, of the particles of Tacca starch, were made for me by Mr. Ceorgo Jackson:—Particles. Length. Breadth. 1. 0.0012. 0.0009. 2. 0.0011. 0.0009. 3*. 0.0008. 0.0007. 4. 0.0006. 0.0005. 5. 0.0004. 0.0004. 6. 0.0003. 0.0003. The most prevalent-sized particle is marked thus *.] which appear circular, mullar-shaped, or polyhedral. Some of the mullar-shaped particles are slightly narrowed at the base. Moreover, the base of the mullar, instend of being flat, appears to me to be hollowed out. The hilum is small and circular; it cracks in a linear or stellate manner. The rings are few and not very distinct.
This fecula is used as a substitute for the West Indian Arrow-root, to which it would probably be equal if it were prepared with equal care. Its composition, like that of other starches, is presumed to be C12H10O10.