Arrowroot is the fecula of Maran′ta arundina′cea or West Indian arrowroot; Sex. Syst. Monandria Monogynia; Nat. Ord. Marantaceæ; a plant, which is a native of South America and the West Indies, where it is largely cultivated in gardens and provision grounds. The tubers or roots are beaten into a pulp, stirred with cold water, removing the fibres with the hand; the milky juice is passed through a fine sieve, and the starch is allowed to subside in the strained fluid. The fecula is then washed, and dried without heat. This is the Arrowroot.
1843, Robley Dunglison, “Demulcents”, in General Therapeutics and Materia Medica, Adapted for a Medical Text Book. [...] In Two Volumes, volume II, Philadelphia, Pa.: Lea and Blanchard, section VIII (Agents whose Action is Prominently Mechanical), page 396