Arrowroot is an edible starch obtained from the underground stems, or rhizomes, of several species of the genus Maranta, family Marantaceae. The most common species of arrowroot is Maranta arundinacea, native to the tropical areas of Florida and the West Indies, and called true, Bermuda, or West Indian arrowroot. Several relatives of true arrowroot are also known locally as arrowroot and have roots containing edible starch. For example, Brazilian arrowroot from the cassava plant (Manihot esculenta) is the source of tapioca. Other starches also called arrowroot are obtained from the genera Curcuma and Tacca. True arrowroot and its relatives are currently cultivated in Australia, southeast Asia, Brazil, and the West Indies.
The roots of arrowroot grow underground to about 1.5 ft (46 cm) long and 2 cm in diameter. Above ground, branched stems grow up to 6 ft (2 m) tall, having big, ovate leaves and a few white flowers. The jointed, light yellow rhizomes are harvested after one year of growth, when they are full of starch. After harvesting, the roots are soaked in water, making their tough, fibrous covering easier to peel off, and the remaining starchy tissue is then beaten into a pulp. The pulp is rinsed with water many times to separate the starch from the residual fiber. The liquid pulp is allowed to dry; the powder that remains is starch. One acre (0.4 ha) of arrowroot can yield 13,200 lb (6 mt) of roots. From this amount, 2,200 lb (1 mt) of starch can be obtained.
Arrowroot starch is very pure; it has no taste or odor, and has minimal nutritional value, other than as a source of energy. It is used in cooking as a thickening agent for soups, sauces, and puddings. What makes this arrowroot unique is that when boiled with a liquid such as water or broth, the gel-like mixture remains transparent, and does not become cloudy or opaque, as is the case with other starches. Arrowroot starch digests easily and is frequently used in food products for babies (for example, arrowroot cookies) or for people who need to eat bland, low protein diets because of illness. Native Americans used this root to absorb poison out of arrow wounds, giving the plant its common name.