There are some exotics in this zone, like the mango, which thrive so well that they are thought to be indigenous.
Among exotics the Australian saltbush spreads successfully over the worst alkali land.
The introduction of other exotics into these zones, - made humid by irrigation, which converts them, the one into true austro-riparian the other into true humid tropical, has revolutionized the agricultural, and indeed the whole, economy of California.
A number of foreign animals have been introduced, and more or less domesticated, and some useful exotics have been cultivated for the purpose of testing their applicability to French agriculture or horticulture; but neither in the case of animals nor of plants has there been any systematic effort to modify the constitution of the species, by breeding largely and selecting the favourable variations that appeared.
Aipi), peanuts, pineapple, guava, chirimoya (Anona cherimolia), pawpaw (Carica papaya), ipecacuanha (Cephaelis), sarsaparilla, vanilla, false jalap (Mirabilis jalapa), copaiba, tolu (Myroxylon toluiferum), rubber-producing trees, dyewoods, cotton and a great number of beautiful hardwoods, such as jacaranda, mahogany, rosewood, quebracho, colo, cedar, walnut, &c. Among the fruits many of the most common are exotics, as the orange, lemon, lime, fig, date, grape, &c., while others, as the banana, caju or cashew (Anacardium occidentale) and aguacate avocado or alligator pear, have a disputed origin.
Among the exotics, sugar-cane, rice and tobacco are cultivated in the warm districts.
Among the more common fruit-trees, some of which are exotics, may be mentioned cacao (Theobroma), orange, lemon, lime, pine-apple, banana, guava (Psidium), breadfruit (Artocarpus), cashew (A nacardium), alligator pear (Pers ea), with the apple, peach, pear, and other fruits of the temperate zone on the elevated plateaus.
In the southern provinces flourish also various subtropical exotics, such as the banana, the West Indian cherimoya, and the prickly pear or Indian fig (Opuntia vulgaris), the last frequently grown as a hedge-plant, as in other Mediterranean countries, and extending even to the southern part of the table-land.