The plants which afford this dye grow chiefly in the East and West Indies, in the middle regions of America, in Africa and Europe.  They are all species of the genera Indigofera, Isatis and Nerium. Indigofera tinctoria or coerulea, furnishes the chief indigo of commerce, and affords in Bengal, Malabar, Madagascar, the Isle of France, and St. Domingo, an article of middling quality, but not in large quantity.  The Indigofera disperma, a plant cultivated in the East Indies and America, grows higher than the preceding, is woody, and furnishes a superior dye-stuff.  The Guatamela indigo comes from this species.

Indigofera Anil grows in the same countries, and also in the West Indies.  The Indigofera Argentea, which flourishes in Africa, yields little indigo, but it is of an excellent quality. I. pseudotinctoria, cultivated in the East Indies, furnishes the best of all. I. glauca is the Egyptian and Arabian species.  There are also the cinerea, erecta (a native of Guinea), hirsuta, glabra, with red flowers, species common to the East, and several others.

The Wrightia tinctoria, of the East Indies, an evergreen, with white blossoms, affords some indigo, as does the Isatis tinctoria, or, Woad, in Europe, and the Polygonum tinctorium, with red flowers, a native of China. Baptisia tinctoria furnishes a blue dye, and is the wild indigo of the United States.

SOURCES OF SUPPLY.—­Indigo is at present grown for commercial purposes in Bengal, and the other provinces of that Presidency, from the 20th to the 30th deg. of north latitude; in the Province of Tinnevelly; in the Madras Presidency; in Java, in the largest of the Philippine islands, in Guatemala, Caraccas, Central America and Brazil.  Bengal is, however, the chief mart for indigo, and the quantity produced in other places is comparatively inconsiderable.  It is also still cultivated in some of the West India islands, especially St. Domingo, but not in large quantities.  Indigo grows wild in several parts of Palestine, but attention seems not to have been given to its cultivation or collection.  On most parts of the eastern and western coasts of Africa, it is indigenous; at Sierra Leone, Natal, and other places it is found abundant.

In our settlements of Honduras, Demerara, and various portions of the American continent, it would amply reward the labor of the cultivator; several inferior sorts of Indigofera being found there indigenous, and only requiring care and culture to improve them.

The quality of indigo depends upon the species of the plant, its ripeness, the soil and climate of its growth, and the mode of manufacture.  The East India, and Brazilian indigo arrives here packed in chests, the Guatemala in ox-hides, called serons.