The black mulberry is distinguished from the white by several characters independently of the black colour of the fruit, which occurs also in a few varieties of the M. alba.[740] It has not a great number of varieties like the latter, which argues a less ancient and a less general cultivation and a narrower primitive area.
Greek and Latin authors, even the poets, have mentioned Morus nigra, which they compare to Ficus sycomorus, and which they even confounded originally with this Egyptian tree.
Commentators for the last two centuries have quoted a number of passages which leave no doubt on this head, but which are devoid of interest in themselves.[741] They furnish no proof touching the origin of the species, which is presumably Persian, unless we are to take seriously the fable of Pyramus and Thisbe, of which the scene was in Babylonia, according to Ovid.
Botanists have not yet furnished any certain proof that this species is indigenous in Persia. Boissier, who is the most learned in the floras of the East, contents himself with quoting Hohenacker as the discoverer of M. nigra in the forests of Lenkoran, on the south coast of the Caspian Sea, and he adds, “probably wild in the north of Persia near the Caspian Sea.”[742] Ledebour, in his Russian flora, had previously indicated, on the authority of different travellers, the Crimea and the provinces south of the Caucasus;[743] but Steven denies the existence of the species in the Crimea except in a cultivated state.[744] Tchihatcheff and Koch found the black mulberry in high wild districts of Armenia. It is very probable that in the region to the south of the Caucasus and of the Caspian Sea Morus nigra is wild and indigenous rather than naturalized. What leads me to this belief is (1) that it is not known, even in a cultivated state, in India, China, or Japan; (2) that it has no Sanskrit name; (3) that it was so early introduced into Greece, a country which had intercourse with Armenia at an early period.[745]
Morus nigra spread so little to the south of Persia, that no certain Hebrew name is known for it, nor even a Persian name distinct from that of Morus alba. It was widely cultivated in Italy until the superiority of the white mulberry for the rearing of silkworms was recognized. In Greece the black mulberry is still the most cultivated.[746] It has become naturalized here and there in these countries and in Spain.[747]
American Aloe—Agave Americana, Linnæus.
This ligneous plant, of the order of Amaryllidaceæ, has been cultivated from time immemorial in Mexico under the names maguey or metl, in order to extract from it, at the moment when the flower stem is developed, the wine known as pulque. Humboldt has given a full description of this culture,[748] and he tells us elsewhere[749] that the species grows in the whole of South America as far as five thousand feet of altitude. It is mentioned[750] in Jamaica, Antigua, Dominica, and Cuba, but it must be observed that it multiplies easily by suckers, and that it is often planted far from dwellings to form fences or to extract from it the fibre known as pite, and this makes it difficult to ascertain its original habitat. Transported long since into the countries which border the Mediterranean, it occurs there with every appearance of an indigenous species, although there is no doubt as to its origin.[751] Probably, to judge from the various uses made of it in Mexico before the arrival of the Europeans, it came originally from thence.
Sugar-Cane—Saccharum officinarum, Linnæus.
The origin of the sugar-cane, of its cultivation, and of the manufacture of sugar, are the subject of a very remarkable work by the geographer, Karl Ritter.[752] I need not follow his purely agricultural and economical details; but for that which interests us particularly, the primitive habitat of the species, he is the best guide, and the facts observed during the last forty years for the most part support or confirm his opinions.
The sugar-cane is cultivated at the present day in all the warm regions of the globe, but a number of historical facts testify that it was first grown in Southern Asia, whence it spread into Africa, and later into America. The question is, therefore, to discover in what districts of the continent, or in which of the southern islands of Asia, the plant exists, or existed at the time it was first employed.