Plants are Trained to Work for Man pp. 337-339 (1921)
A New Creation In Corn
Our common corn Zea Mays has shown wonderful adaptability to various soils and climates and also to the various uses for which it is grown, much more so than any other grass or grain. Next to it in variability are the Sorghums, which include the various Kaffir corns, broom corns, and annual sugar canes. These are two very distinct species, one of which is a native of Africa, the other of America and there is no record of any new variety having been produced by crossing. Six years ago, after numerous trials, a few kernels were produced on an ear of Stowell's Evergreen sweet corn from pollen of the white goose neck Kaffir corn. These precious kernels were carefully planted one by one the next season and all but two were Stowell's Evergreen to all intents and purposes, but two ripened weeks earlier and were almost true Kaffir corns with compact, crooked, drooping "heads," containing many scattering hard, round kernels, also bearing “goose neck,” drooping ears, somewhat resembling popcorn. The next season all were planted and a new corn, in many respects resembling white rice popcorn, but with more nearly globular kernels, was produced but the ears were branched or "many fingered" and bore kernels not only on the out side but on the inside of the ears, producing an enormous number of kernels to the cluster. As the cobs had to be crushed to obtain the corn, selections were made of short "stubby" ears which bore kernels only on the outside.
This most unique corn is early, quite uniform and one of the best popping corns. It pops out pure white, sweet, and with a whirlwind of vehemence. This amazing production is of great interest, not only to growers, but also to botanists.
Howard: Luther Burbank, a Victim of Hero Worship (1945)
"Sorghum Pop.—Announced in 1917 as a cross between Burpee's Improved Stowell's Evergreen and the gooseneck Kaffir corn, the former being pollinated by the latter. The cross was effected about 1912 after numerous earlier trials had failed. The grains from the hybrid ear were planted, but all the resultant plants except two, were like the pistillate parent. The two exceptions ripened two weeks earlier "and were almost true Kaffir corn with compact, crooked, drooping heads, containing many scattering hard, round kernels, also bearing gooseneck drooping ears, somewhat resembling popcorn. The next season all were planted and a new corn, in many respects resembling white rice popcorn, but with more nearly globular kernels was produced, but the ears were branched or many-fingered and bore kernels, not only on the outside, but on the inside of the ears, producing an enormous number of kernels to the cluster. As these had to be crushed to obtain the corn, selections were made of short, stubby ears, which bore kernels only on the outside." It was recommended as a popping corn.
Agronomists have been skeptical of any such cross having been made and say that the so-called Sorghum Pop is only the old Japanese hulless corn. The cross is a difficult one and has not been repeated, but this does not necessarily mean that it cannot be done. The same objection was made regarding the plum-apricot cross but this feat was duplicated many years later by two experimenters, working independently.