Flint Corn

​A dominant gene (Fl) causes more hard, vitreous starch to be deposited in areas surrounding the softer starch of the endosperm.  Much of the hardness is due to a hydrophobic protein called zein.  One of the effects for this protein surrounding the starch is repelling water and, consequently, germination is less likely to be affected by freeze or moisture after reaching black layer before harvest.  This character probably contributed to the wide use of flint corn types in the northeast USA by locals when the Europeans arrived and the continued use of New England flints by farmers in that area.  Flint corn also became common elsewhere and Argentine flint hybrids still are popular in Argentina.  Flint corn varieties are popular in Europe, especially in the northern area.   The initial breeding stock for much of Asia apparently came from flint corn types, with this character remaining among many current hybrids.
 
Popcorn is a flint corn, the hard starch with the hydrophobic protein contributing to the popping pressure in the kernel as the steam builds within the softer starch center of the endosperm.
 
The homozygous recessive form of the Fl gene results in more soft starch in floury types of kernels.  This became a feature of corn common in the southeastern USA and elsewhere that corn flour was used.  As the farmers saved seed up until the 1930’s, the flints tended to be most common in the northern USA and more soft starch (floury) types were in the Southeastern USA. Many of the latter were dented, being from crosses of soft types and Caribbean flints. A mix of local cultures use of food and tradition determined maintenance of many kernel types.