I do not examine whether Phaseolus vulgaris existed in both hemispheres previous to cultivation, because examples of this nature are exceedingly rare among non-aquatic phanerogamous plants of tropical countries. Perhaps there is not one in a thousand, and even then human agency may be suspected.[1716] To open this question in the case of Ph. vulgaris, it should at least be found wild in both old and new worlds, which has not happened. If it had occupied so vast an area, we should see signs of it in individuals really wild in widely separate regions on the same continent, as is the case with the following species, Ph. lunatas.
Scimetar-podded Kidney Bean, or Sugar Bean.—Phaseolus lunatus, Linnæus; Phaseolus lunatus macrocarpus; Bentham, Ph. inamœnus, Linnæus.
This haricot, as well as that called Lima, is so widely diffused in tropical countries, that it has been described under different names.[1717] All these forms can be classed in two groups, of which Linnæus made different species. The commonest in our gardens is that which has been called since the beginning of the century the Lima haricot. It may be distinguished by its height, by the size of its pods and beans. It lasts several years in countries which are favourable to it.
Linnæus believed that his Ph. lunatus came from Bengal and the other from Africa, but he gives no proof. For a century his assertions were repeated. Now, Bentham,[1718] who is careful about origins, believes the species and its variety to be certainly American; he only doubts about its presence as a wild plant both in Africa and Asia. I see no indication whatever of ancient existence in Asia. The plant has never been found wild, and it has no name in the modern languages of India or in Sanskrit.[1719] It is not mentioned in Chinese works. Anglo-Indians call it French bean,[1720] like the common haricot, which shows how modern is its cultivation.
It is cultivated in nearly all tropical Africa. However, Schweinfurth and Ascherson[1721] do not mention it for Abyssinia, Nubia, or Egypt. Oliver[1722] quotes a number of specimens found in Guinea and the interior of Africa, without saying whether they were wild or cultivated. If we suppose the species of African origin or of very early introduction, it would have spread to Egypt and thence to India.
The facts are quite different for South America. Bentham mentions wild specimens from the Amazon basin and Central Brazil. They belong especially to the large variety (macrocarpus), which abounds also in the Peruvian tombs of Ancon, according to Wittmack.[1723] It is evidently a Brazilian species, diffused by cultivation, and perhaps long since naturalized here and there in tropical America. I am inclined to believe it was introduced into Guinea by the slave trade, and that it spread thence into the interior and the coast of Mozambique.
Moth, or Aconite-leaved Kidney Bean—Phaseolus aconitifolius, Willdenow.
An annual species grown in India as fodder, and of which the seeds are eatable, though but little valued. The Hindustani name is mout, among the Sikhs moth. It is somewhat like Ph. trilobus, which is cultivated for the seed. Ph. aconitifolius is wild in British India from Ceylon to the Himalayas.[1724] The absence of a Sanskrit name, and of different names in modern Indian languages, points to a recent cultivation.
Three-lobed Kidney Bean—Phaseolus trilobus, Willdenow.
One of the most commonly cultivated species in India;[1725] at least in the last few years, for Roxburgh,[1726] at the end of the eighteenth century, had only seen it wild. All authors agree in considering it as wild from the foot of the Himalayas to Ceylon. It also exists in Nubia, Abyssinia, and Zambesi;[1727] it is not said whether wild or cultivated. Piddington gives a Sanskrit name, and several names in modern Indian languages, which shows that the species has been cultivated, or at least known for three thousand years.