Gartner kept, during several years, a dwarf kind of maize with yellow seeds, and a tall variety with red seeds growing near each other in his garden; and although these plants have separated sexes, they never naturally crossed.

几年来，加特纳在他的花园里种植了一种矮小的黄色种子玉米和一种高大的红色种子玉米。尽管这些植物有两性分离， 但它们从不自然杂交。