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.
The abundance of Indian and Malay names[1682] shows a somewhat ancient cultivation. Piddington even gives a Sanskrit name, arhuku, which was not known to Roxburgh, but he gives no proof in support of his assertion. The name may have been merely supposed from the Hindu and Bengali names urur and orol. No Semitic name is known.
In Africa the cajan is often found from Zanzibar to the coast of Guinea.[1683] Authors say it is cultivated, or else make no statement on this head, which would seem to show that the specimens are sometimes wild. In Egypt this cultivation is quite modern, of the nineteenth century.[1684]
Briefly, then, I doubt that the species is really wild in Asia, and that it has been grown there for more than three thousand years. If more ancient peoples had known it, it would have come to the knowledge of the Arabs and Egyptians before our time. In tropical Africa, on the contrary, it is possible that it has existed wild or cultivated for a very long time, and that it was introduced into Asia by ancient travellers trading between Zanzibar and India or Ceylon.
The genus Cajanus has only one species, so that no analogy of geographical distribution leads us to believe it to be rather of Asiatic than African origin, or vice versâ.
Carob Tree[1685]—Ceratonia siliqua, Linnæus.
The seeds and pods of the carob are highly prized in the hotter parts of the Mediterranean basin, as food for animals and even for man. De Gasparin[1686] has given interesting details about the raising, uses, and habitation of the species as a cultivated tree. He notes that it does not pass the northern limit beyond which the orange cannot be grown without shelter. This fine evergreen tree does not thrive either in very hot countries, especially where there is much humidity. It likes the neighbourhood of the sea and rocky places. Its original country, according to Gasparin, is “probably the centre of Africa. Denham and Clapperton found it in Burnou.” This proof seems to me insufficient, for in all the Nile Valley and in Abyssinia the carob is not wild nor even cultivated.[1687] R. Brown does not mention it in his account of Denham and Clapperton’s journey. Travellers have seen it in the forests of Cyrenaica between the high-lands and the littoral; but the able botanists who have drawn up the catalogue of the plants of this country are careful to say,[1688] “perhaps indigenous.” Most botanists merely mention the species in the centre and south of the Mediterranean basin, from Spain and Marocco to Syria and Anatolia, without inquiring closely whether it is indigenous or cultivated, and without entering upon the question of its true country previous to cultivation. Usually they indicate the carob tree, as “cultivated and subspontaneous, or nearly wild.” However, it is stated to be wild in Greece by Heldreich, in Sicily by Gussone and Bianca, in Algeria by Munby;[1689] and these authors have each lived long enough in the country for which each is quoted to form an enlightened opinion.
Bianca remarks, however, that the carob tree is not always healthy and productive in those restricted localities where it exists in Sicily, in the small adjacent islands, and on the coast of Italy. He puts forward the opinion, moreover, based upon the similarity of the Italian name carrubo with the Arabic word, that the species was anciently introduced into the south of Europe, the species being of Syrian or north African origin. He maintains as probable the theory of Hœfer and Bonné,[1690] that the lotus of the lotophagi was the carob tree, of which the flower is sweet and the fruit has a taste of honey, which agrees with the expressions of Homer. The lotus-eaters dwelt in Cyrenaica, so that the carob must have been abundant in their country. If we admit this hypothesis we must suppose that Pliny and Herodotus did not know Homer’s plant, for the one describes the lotus as bearing a fruit like a mastic berry (Pistacia lentiscus), the other as a deciduous tree.[1691]
An hypothesis regarding a doubtful plant formerly mentioned by a poet can hardly serve as the basis of an argument upon facts of natural history. After all, Homer’s lotus plant perhaps existed only in the fabled garden of Hesperides. I return to more serious arguments, on which Bianca has said a few words.