4. In the 19th century, farm Americans to industrialize.
especially
provided the income for
5. When the USDA was founded in 1862, seed
important part of its efforts.
and
were an
6. Green plants form the base of the
energy flow through an
and the beginning of the
7. The most important food plants are grains of the
family.
8. In many tropical countries, starchy.
crops are the basic foods.
9.
plants are used to beautify yards, parks and indoor spaces.