It is remarkable that, though the species is diffused in three continents, the varieties are not numerous. Two are cited, based only upon the yellow or reddish colour of the flower, which were formerly regarded as distinct species; but a more attentive examination has resulted in their being classed as one, in accordance with Linnæus’ opinion.[1673] The small number of variations obtained even in the organ for which the species is cultivated is a sign of no very ancient culture. Its habitation previous to culture is uncertain. The best botanists have sometimes supposed it to be a native of India, sometimes of tropical Africa. Bentham, who has made a careful study of the leguminous plants, believed in 1861 in the African origin; in 1865 he inclined rather to Asia.[1674] The problem is, therefore, an interesting one. There is no question of an American origin. The cajan was introduced into the West Indies from the coast of Africa by the slave trade, as the common names quoted above show,[1675] and the unanimous opinion of authors or American floras. It has also been taken to Brazil, Guiana, and into all the warm parts of the American continent. The facility with which the species is naturalized would alone prevent attaching great importance to the statements of collectors, who have found it more or less wild in Asia or in Africa; and besides, these assertions are not precise, but are usually doubtful. Most writers on the flora of continental India have only seen the plant cultivated,[1676] and none, to my knowledge, affirms that it exists wild. For the island of Ceylon Thwaites says,[1677] “It is said not to be really wild, and the country names seem to confirm this.” Sir Joseph Hooker, in his _Flora of British India_, says, “Wild (?) and cultivated to the height of six thousand feet in the Himalayas.” Loureiro[1678] gives it as cultivated and non-cultivated in China and Cochin-China. Chinese authors do not appear to have spoken of it, for the species is not named by Bretschneider in his work _On the Study_, etc. In the Sunda Isles it is mentioned as cultivated, and that rarely, at Amboyna at the end of the eighteenth century, according to Rumphius.[1679] Forster had not seen it in the Pacific Isles at the time of Cook’s voyages, but Seemann says that it has been recently introduced by missionaries into the Fiji Isles.[1680] All this argues no very ancient extension of cultivation to the east and south of the continent of Asia. Besides the quotation from Loureiro, I find the species indicated on the mountain of Magelang, Java;[1681] but, supposing this to be a true and ancient wild growth in both cases, it would be very extraordinary not to find the species in many other Asiatic localities.