This quotation is highly significant. With it should be compared
the fact that there is no evidence that corn or anything else was
cultivated in California west of the Rio Colorado Valley.
California is a region famous throughout America for its
agriculture, but its crops are European in origin. Even in the
case of fruits, such as the grape, which have American
counterparts, the varieties actually cultivated were brought from
Europe. Wheat and barley, the chief foodstuffs for which
California and similar subtropical regions are noted, were
unknown in the New World before the coming of the white man. In
pre-Columbian America corn was the only cultivated cereal. The
other great staples of early American agriculture were beans and
pumpkins. All three are preeminently summer crops and need much
water in July and August. In California there is no rain at this
season. Though the fall rains, which begin to be abundant in
October and November, do not aid these summer crops, they favor
wheat and barley. The winter rains and the comparatively warm
winter weather permit these grains to grow slowly but
continuously. When the warm spring arrives, there is still enough
rain to permit wheat and barley to make a rapid growth and to
mature their seeds long before the long, dry summer begins. The
comparatively dry weather of May and June is just what these
cereals need to ripen the crop, but it is fatal to any kind of
agriculture which depends on summer rain.

Crops can of course be grown during the summer in California by
means of irrigation, but this is rarely a simple process. If
irrigation is to be effective in California, it cannot depend on