The plant appears to be wild, especially in Otahiti.[289] It is also wild in Ceylon, according to Thwaites, who has studied botany for a long time in that island. It is mentioned also in India[290] and in Australia,[291] but its wild condition is not affirmed—a fact always difficult to establish in the case of a species cultivated on the banks of streams, and which is propagated by bulbs. Moreover, it is sometimes confounded with the _Colocasia indica_ of Kunth, which grows in the same manner, and is found here and there in cultivated ground; and this species grows wild, or is naturalized in the ditches and streams of Southern Asia, although its history is not yet well known. +Konjak+—_Amorphophallus Konjak_, Koch; _Amorphophallus Rivieri_, du Rieu, var. _Konjak_, Engler.[292] The konjak is a tuberous plant of the family Araceæ, extensively cultivated by the Japanese, a culture of which Vidal has given full details in the _Bulletin de la Société d’Acclimatation_ of July, 1877. It is considered by Engler as a variety of _Amorphophallus Rivieri_, of Cochin-China, of which horticultural periodicals have given several illustrations in the last few years.[293] It can be cultivated in the south of Europe, like the dahlia, as a curiosity; but to estimate the value of the bulbs as food, they should be prepared with lime-water, in Japanese fashion, so as to ascertain the amount of fecula which a given area will produce. Dr. Vidal gives no proof that the Japanese plant is wild in that country. He supposes it to be so from the meaning of the common name, which is, he says, _konniyakou_ or _yamagonniyakou_, _yama_ meaning “mountain.” Franchet and Savatier[294] have only seen the plant in gardens. The Cochin-China variety, believed to belong to the same species, grows in gardens, and there is no proof of its being wild in the country. +Yams+—_Dioscorea sativa_, _D. batatas_, _D. japonica_ and _D. alata_. The 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.