Origin of Cultivated Plants. Alphonse de Candolle

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СКАЧАТЬ yams, monocotyledonous plants, belonging to the family Dioscorideæ, constitute the genus Dioscorea, of which botanists have described about two hundred species, scattered over all tropical and sub-tropical countries. They usually have rhizomes, that is, underground stems or branches of stems, more or less fleshy, which become larger when the annual, exposed part of the plant is near its decay.295 Several species are cultivated in different countries for these farinaceous rhizomes, which are cooked and eaten like potatoes.

      The botanical distinction of the species has always presented difficulties, because the male and female flowers are on different individuals, and because the characters of the rhizomes and the lower part of the exposed stems cannot be studied in the herbarium. The last complete work is that of Kunth,296 published in 1850. It requires revision on account of the number of specimens brought home by travellers in these last few years. Fortunately, with regard to the origin of cultivated species, certain historical and philological considerations will serve as a guide, without the absolute necessity of knowing and estimating the botanical characters of each.

      Roxburgh enumerates several Dioscoreæ297 cultivated in India, but he found none of them wild, and neither he nor Piddington298 mentions Sanskrit names. This last point argues a recent cultivation, or one of originally small extent, in India, arising either from indigenous species as yet undefined, or from foreign species cultivated elsewhere. The Bengali and Hindu generic name is alu, preceded by a special name for each species or variety; kam alu, for instance, is Dioscorea alata. The absence of distinct names in each province also argues a recent cultivation. In Ceylon, Thwaites299 indicates six wild species, and he adds that D. sativa, L., D. alata, L., and D. purpurea, Roxb., are cultivated in gardens, but are not found wild.

      The Chinese yam, Dioscorea batatas of Decaisne,300 extensively cultivated by the Chinese under the name of Sain-in, and introduced by M. de Montigny into European gardens, where it remains as a luxury, has not hitherto been found wild in China. Other less-known species are also cultivated by the Chinese, especially the chou-yu, tou-tchou, chan-yu, mentioned in their ancient works on agriculture, and which has spherical rhizomes (instead of the pyriform spindles of the D. batatas). The names mean, according to Stanislas Julien, mountain arum, whence we may conclude the plant is really a native of the country. Dr. Bretschneider301 gives three Dioscoreæ as cultivated in China (D. batatas, alata, sativa), adding, “The Dioscorea is indigenous in China, for it is mentioned in the oldest work on medicine, that of the Emperor Schen-nung.”

       Dioscorea japonica, Thunberg, cultivated in Japan, has also been found in clearings in various localities, but Franchet and Savatier302 say that it is not positively known to what degree it is wild or has strayed from cultivation. Another species, more often cultivated in Japan, grows here and there in the country according to the same authors. They assign it to Dioscorea sativa of Linnæus; but it is known that the famous Swede had confounded several Asiatic and American species under that name, which must either be abandoned or restricted to one of the species of the Indian Archipelago. If we choose the latter course, the true D. sativa would be the plant cultivated in Ceylon with which Linnæus was acquainted, and which Thwaites calls the D. sativa of Linnæus. Various authors admitted the identity of the Ceylon plant with others cultivated on the Malabar coast, in Sumatra, Java, the Philippine Isles, etc. Blume303 asserts that D. sativa, L., to which he attributes pl. 51 in Rheede’s Hortus Malabaricus, vol. viii., grows in damp places in the mountains of Java and of Malabar. In order to put faith in these assertions, it would be necessary to have carefully studied the question of species from authentic specimens.

      The yam, which is most commonly cultivated in the Pacific Isles under the name ubi, is the Dioscorea alata of Linnæus. The authors of the seventeenth and eighteenth centuries speak of it as widely spread in Tahiti, in New Guinea, in the Moluccas, etc.304 It is divided into several varieties, according to the shape of the rhizome. No one pretends to have found this species in a wild state, but the flora of the islands whence it probably came, in particular that of Celebes and of New Guinea, is as yet little known.

      Passing to America, we find there also several species of this genus growing wild, in Brazil and Guiana, for instance, but it seems more probable that the cultivated varieties were introduced. Authors indicate but few cultivated species or varieties (Plumier one, Sloane two) and few common names. The most widely spread is yam, igname, or inhame, which is of African origin, according to Hughes, and so also is the plant cultivated in his time in Barbados.305

      He says that the word yam means “to eat,” in several negro dialects on the coast of Guinea. It is true that two travellers nearer to the date of the discovery of America, whom Humboldt quotes,306 heard the word igname pronounced on the American continent: Vespucci in 1497, on the coast of Paria; Cabral in 1500, in Brazil. According to the latter, the name was given to a root of which bread was made, which would better apply to the manioc, and leads me to think there must be some mistake, more especially since a passage from Vespucci, quoted elsewhere by Humboldt,307 shows the confusion he made between the manioc and the yam. D. Cliffortiana, Lam., grows wild in Peru308 and in Brazil,309 but it is not proved to be cultivated. Presl says verosimiliter colitur, and the Flora Brasiliensis does not mention cultivation.

      The species chiefly cultivated in French Guiana, according to Sagot,310 is Dioscoreæ triloba, Lam., called Indian yam, which is also common in Brazil and the West India Islands. The common name argues a native origin, whereas another species, D. cayennensis, Kunth, also cultivated in Guiana, but under the name of negro-country yam, was most likely brought from Africa, an opinion the more probable that Sir W. Hooker likens a yam cultivated in Africa on the banks of the Nun and the Quorra,311 to D. cayennensis. Lastly, the free yam of Guiana is, according to Dr. Sagot, D. alata introduced from the Malay Archipelago and Polynesia.

      In Africa there are fewer indigenous Dioscoreæ than in Asia and America, and the culture of yams is less widely spread. On the west coast, according to Thonning,312 only one or two species are cultivated; Lockhardt313 only saw one in Congo, and that only in one locality. Bojer314 mentions four cultivated species in Mauritius, which are, he says, of Asiatic origin, and one, D. bulbifera, Lam., from India, if the name be correct. He asserts that it came from Madagascar, and has spread into the woods beyond the plantations. In Mauritius it bears the name Cambare marron. Now, cambare is something like the Hindu name kam, and marron (marroon) indicates a plant escaped from cultivation. The ancient Egyptians cultivated no yams, which argues a cultivation less ancient in India than that of the colocasia. Forskal and Delile mention no yams cultivated in Egypt at the present day.

      To sum up: several Dioscoreæ wild in Asia (especially in the Asiatic Archipelago), and others less numerous growing in America and in Africa, have been introduced into cultivation as alimentary plants, probably more recently than many other species. This last conjecture is based on the absence of a Sanskrit name, on the limited geographical СКАЧАТЬ