Origin of Cultivated Plants. Alphonse de Candolle

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plant is cultivated sometimes for its fleshy root (red beet), sometimes for its leaves, which are used as a vegetable (white beet), but botanists are generally agreed in not dividing the species. It is known from other examples that plants slender rooted by nature easily become fleshy rooted from the effects of soil or cultivation.

      The slender-rooted variety grows wild in sandy soil, and especially near the sea in the Canary Isles, and all along the coasts of the Mediterranean Sea, and as far as the Caspian Sea, Persia, and Babylon,174 perhaps even as far as the west of India, whence a specimen was brought by Jaquemont, although it is not certain that it was growing wild. Roxburgh’s Indian flora, and Aitchison’s more recent flora of the Punjab and of the Sindh, only mention the plant as a cultivated species.

      It has no Sanskrit name,175 whence it may be inferred that the Aryans had not brought it from western temperate Asia, where it exists. The nations of Aryan race who had previously migrated into Europe probably did not cultivate it, for I find no name common to the Indo-European languages. The ancient Greeks, who used the leaves and roots, called the species teutlion;176 the Romans, beta. Heldreich177 gives also the ancient Greek name sevkle, or sfekelie which resembles the Arab name selg, silq,178 among the Nabatheans. The Arab name has passed into the Portuguese selga. No Hebrew name is known. Everything shows that its cultivation does not date from more than three or four centuries before the Christian era.

      The red and white roots were known to the ancients, but the number of varieties has greatly increased in modern times, especially since the beetroot has been cultivated on a large scale for the food of cattle and for the production of sugar. It is one of the plants most easily improved by selection, as the experiments of Vilmorin have proved.179

      Manioc—Manihot utilissima, Pohl; Jatropha manihot, Linnæus.

      The manioc is a shrub belonging to the Euphorbia family, of which several roots swell in their first year; they take the form of an irregular ellipse, and contain a fecula (tapioca) with a more or less poisonous juice.

      It is commonly cultivated in the equatorial or tropical regions, especially in America from Brazil to the West Indies. In Africa the cultivation is less general, and seems to be more recent. In certain Asiatic colonies it is decidedly of modern introduction. It is propagated by budding.

      Botanists are divided in opinion whether the innumerable varieties of manioc should be regarded as forming one, two, or several different species. Pohl180 admitted several besides his Manihot utilissima, and Dr. Müller,181 in his monograph on the Euphorbiaceæ, places the variety aipi in an allied species, M. palmata, a plant cultivated with the others in Brazil, and of which the root is not poisonous. This last character is not so distinct as might be believed from certain books and even from the assertions of the natives. Dr. Sagot,182 who has compared a dozen varieties of manioc cultivated at Cayenne, says expressly, “There are maniocs more poisonous than others, but I doubt whether any are entirely free from noxious principles.”

      It is possible to account for these singular differences of properties in very similar plants by the example of the potato. The Manihot and Solanum tuberosum both belong to suspected families (Euphorbiaceæ and Solanaceæ). Several of their species are poisonous in some of their organs; but the fecula, wherever it is found, is never harmful, and the same holds good of the cellular tissue, freed from all deposit; that is to say, reduced to cellulose. In the preparation of cassava, or manioc flour, great care is taken to scrape the outer skin of the root, then to pound or crush the fleshy part so as to express the more or less poisonous juice, and finally the paste is submitted to a baking which expels the volatile parts.183 Tapioca is the pure fecula without the mixture of the tissues which still exist in the cassava. In the potato the outer pellicle contracts noxious qualities when it is allowed to become green by exposure to the light, and it is well known that unripe or diseased tubers, containing too small a proportion of fecula with much sap, are not good to eat, and would cause positive harm to persons who consumed any quantity of them. All potatoes, and probably all maniocs, contain something harmful, which is observed even in the products of distillation, and which varies with several causes; but only matter foreign to the fecula should be mistrusted.

      The doubts about the number of species into which the cultivated manihots should be divided are no source of difficulty regarding the question of geographic origin. On the contrary, we shall see that they are an important means of proving an American origin.

      The Abbé Raynal had formerly spread the erroneous opinion that the manioc was imported into America from Africa. Robert Brown184 denied this in 1818, but without giving reasons in support of his opinion; and Humboldt,185 Moreau de Jonnes,186 and Saint Hilaire187 insisted upon its American origin. It can hardly be doubted for the following reasons: —

      1. Maniocs were cultivated by the natives of Brazil, Guiana, and the warm region of Mexico before the arrival of the Europeans, as all early travellers testify. In the West Indies this cultivation was, according to Acosta,188 common enough in the sixteenth century to inspire the belief that it was also there of a certain antiquity.

      2. It is less widely diffused in Africa, especially in regions at a distance from the west coast. It is known that manioc was introduced into the Isle of Bourbon by the Governour Labourdonnais.189 In Asiatic countries, where a plant so easy to cultivate would probably have spread had it been long known on the African continent, it is mentioned here and there as an object of curiosity of foreign origin.190

      3. The natives of America had several ancient names for the varieties of manioc, especially in Brazil,191 which does not appear to have been the case in Africa, even on the coast of Guinea.192

      4. The varieties cultivated in Brazil, in Guiana, and in the West Indies are very numerous, whence we may presume a very ancient cultivation. This is not the case in Africa.

      5. The forty-two known species of the genus Manihot, without counting M. utilissima, are all wild in America; most of them in Brazil, some in Guiana, Peru, and Mexico; not one in the old world.193 It is very unlikely that a single species, and that the cultivated one, was a native both of the old and of the new world, and all the more so since in the family Euphorbiaceæ the area of the woody species is usually restricted, and since phanerogamous plants are very rarely common to Africa and America.

      The American origin of the manioc being thus established, it may be asked how the species has been introduced into Guinea and Congo. It was probably the result of the frequent communications established in the sixteenth century by Portuguese merchants and slave-traders.

      The Manihot utilissima and the allied species or variety called aipi, which is also cultivated, have not been found in an undoubtedly wild state. Humboldt and Bonpland, indeed, found upon the banks of the Magdalena a plant of Manihot utilissima which they called almost wild,194 but Dr. Sagot assures me that it has not been found in Guiana, and that botanists who have explored the hot region in Brazil have not been more fortunate. We gather as much from the expressions of Pohl, who has carefully studied these plants, and who was acquainted with the collections of Martius, and had no doubt of their

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