In the temperate regions of the world wheat is the principal cereal
grown, and there are many different varieties suited to varying
conditions. As we go farther north, barley, oats and rye increase in
importance, and although they are grown for special purposes along with
wheat, it is important to note that they will thrive in countries and
under conditions not suited to wheat. Starting again from the temperate
zones and traveling north or south, as the case may be, we enter the
warmer countries where wheat cultivation is often associated with that
of rice, corn, sorghum, etc. In the tropics, however, wheat will not
thrive at low elevations, but rice, corn, sorghum and various millets
form the great cereal crops, their relative importance varying in
different countries.
The grasses proper grow upon our meadows, pastures, fields and in the
woods and are only used as food for cattle.