Anyone who gardens is probably growing New World domesticates, including those who dedicate all their efforts to trying to grow the elusive 1,000-pound pumpkin. Thousands of wildflowers are also finding increasing popularity among gardeners. Just a few of the sophisticated native plants I have growing in my garden are the primrose, Mexican mint marigold, butterfly weed, black-eyed Susan, and hairy zexmenia. Such wild plants are the raw material for gardeners. With food crops, cultivators can select for edible wild plants that yield more food per plant, are better suited to particular conditions, more hardy, and so forth.
Gardeners select blooms and foliage for size, form, texture, and color.
Five hundred years ago, the New World, Asia, and Africa were full of raw material for plant domestication, while Europe had relatively little. In The Principles of Gardening, Hugh Johnson argues that the flora of Europe suffered much greater damage during the last glaciation than did that of Asia and the Americas. In North America and China, plant communities survived by migrating southward as the glaciers crept forward, and they recolonized as the glaciers retreated. European plants were cut off by the Mediterranean Sea, and only the most hardy survived. Europe's colonial expansion changed that,and Europeans gardens began to fill with the exotic flowers of Africa, Asia, and, eventually, the Americas.