1116. The influence of civilisation and culture, in increasing the number of plants in a country, is very considerable, and operates directly, by introducing new species for culture in gardens, fields or timber-plantations ; and, indirectly, by the acclimatising and final naturalisation of many species, by the influence of winds and birds in scattering their seeds. The vine and the fig are not indigenous to France, but were brought there by birds. In like manner the orange was naturalised in the south of Italy, and many herbaceous plants of the Levant, both in France and Britain ; some, as the cabbage, cherry, and apple, probably during the subjection of England to the Romans. The narrow-leaved elm was brought from the Holy Land during the crusades. Phascolus vulgaris and Balasmina hortensis were originally from India ; and Datura Stramonium, which is now naturalised in Europe, came originally from India or Abyssinia. Buckwheat, and most species of corn and peas, came also from the East; and along with them several plants found among corn only, such as Centaurea Cyanus, Agrostemma Githago, Raphanus Raphanistrum, and Myagrum sativum. The country whence the most valuable grasses migrated is not known. Bruce says he found the oat wild in Abyssinia; and wheat and millet have been found in a wild state in hilly situations in the East Indies. The Romans were unacquainted with either potatoes or rye; and the native country of the former, Humboldt declares to be totally unknown.
