America's Crop Heritage


other plants whose cultivation awaited "discovery" by the plant
explorers sent out from Europe. Seeds and cuttings of many of
these native plants were sent to Europe for trial before they were
brought back to the North American colonies for cultivation.2
Some of them have been adapted to our agriculture through the
persistent efforts at adaptation by the settlers. Many others are
tropical plants not suited to the temperate zone. (1)

 METHODS AND TERMINOLOGY
 In discussing plant introductions, we are interested chiefly in
living flora imported for agricultural or other economic uses,
rather than for botanical purposes. The returns to society from this
work are comparable to the benefits derived from scientific inven-
tion and discovery. Frequently the discovery of a single useful
plant is of sufficient value to offset the expense and labor of col-
lecting many hundreds of worthless introductions.
 Plant introduction has been practiced since the dawn of agri-
cultural history; but to be successful, it requires a knowledge of
the methods of cultivation, harvesting, and uses of plants. In
increasing farm production, superior plant varieties are factors
that need to be considered along with tillage, rotation, fertilizers,
and irrigation. Recent methods of introduction are based on
plant breeding according to the relatively new laws of genetics.
Even these efforts, however, depend heavily upon a wealth of
plant stocks for the factors not already present in our native
or acquired flora.
 Breeding experiments seek to develop such qualities as resist-
ance to disease and insects; indifference to cold, aridity, heat, and
wind; and tolerance of peculiar soil conditions such as acidity
and alkalinity. The extension of the harvest season-and changes
in the character of the product such as color, size, shape, flavor,
and strength-are also factors. Other changes bring about advan-
tages in handling the plants from planting to marketing, or make
possible the extension of the crop into new areas.
 The traditional means of improving plants is by selection;
and skilled breeding, or hybridizing, has helped to create new
 'Among these are the agave, arrowroot, many varieties of kidney and lima beans,
cacao, chili pepper, cashew nuts, cherimoya, cocoa, cotton (Gossypium barbadense),
gourds, guava, Jerusalem artichoke, manioc or cassava, mate or Paraguay tea, papaya,
peanut, pineapple, prickly pear, pumpkin, quinoa, squash, sweet potato, tobacco,
and tomato.