22. Rice grows best in hot countries, and as the varieties most used require to be submerged for a considerable period in order to develop properly, their cultivation is restricted to localities where yearly flooding may be practised. At the same time, this peculiarity makes it possible to grow rice where no other grain will thrive. Enormous quantities are produced every year in the warm and moist regions of China, India, and the neighboring islands, and in our southern coast States. Since it forms one of the principal articles of diet in the densely populated countries of eastern Asia, and has come to be very widely used in other parts of the world, rice doubtless serves as food for more human beings than any other grain.

Fig. 20. Map showing, as in Fig. 16, native home and present range of rice.

Fig. 20.-Map showing, as in Fig. 16, native home and present range of rice. (Original.)