Compared with the standard sweet corn types, these varieties have a distinctly higher content of sugar and are therefore called “super sweet” or “extra sweet”. In these hybrids there is, apart from the above-described recessive gene su1, another recessive gene, which is called sh2 (shrunken two gene) by the geneticists. As a consequence of this gene, the transformation of sugar into starch is still more slowed down. Extra sweet varieties have such a high sugar content that they can be consumed without cooking directly from the field, and someone may find this type even too sweet. However, these hybrids have a great advantage as regards production and trade, as the temporal margin for their marketing is distinctly longer, because even after some days of storage within the marketing chain, the quality of these varieties differs considerably from that of field corn harvested by the way side. To maintain their quality advantage, extra sweet varieties must be isolated not only from field corn, but also from normal sweet varieties.