A Typical Corn Stalk
This picture is shown to make clear the relations of pollen-bearing and ovule-bearing organs in the mechanism of the corn plant. The pollen, being borne in the tassel at the top, naturally silts down, as carried by the wind, on the "silk" which constitutes the stigmas of the seed-bearing flower. It is obvious that the opposite arrangement of the two types of flowers would not have answered at all.
This image is from: Luther Burbank: his methods and discoveries and their practical application. Volume 8 Chapter 1