Hybrid plants as we know them did not exist before Charles Darwin. Darwin proposed that certain plant species changed over time as the traits that made that species better became prominent. Prior to humans becoming part of the process by crossbreeding plants on purpose, certain plants naturally hybridized on their own. We know about these early hybrids because the modern versions of the plants that we eat look very different from the early versions.
Wheat is among the first crops ever to be cultivated by mankind. Archeological digs in Eastern Iraq showed that farmers cultivated a primitive version of wheat more than 9,000 years ago. This early wheat became both the basis for bread and livestock feed. Prior to that, wheat underwent a number of natural mutations that changed it from a grass to an edible grain. Hybrid species that are distantly related to wheat include emmer, einkorn, spelt and durum.
According to the University of Illinois Extension, roses exist in the fossil record from more than 35 million years ago. Over this time the plant underwent a number of mutations and natural divisions to become the rose that we know today. There are more than 150 species of rose that grow across the Northern Hemisphere from Alaska to Mexico. Roses differ in appearance from tall climbing roses to shrub and miniature varieties. Distant relations to the rose include both strawberries and apples.
Humans have used and cultivated grapes long before any other fruit. According to the National Grape Cooperative, hunter/gatherers picked wild grapes that grew on south-facing hillsides long before farmers cultivated the first grapes. Archeologists working in the Black Sea region found evidence of the first cultivated grapes in a Neolithic village dated to 6,000 B.C. As farmers began growing grapes in earnest, early hybrids were created to improve grape size, cluster quantity and hardiness.
Corn as we know it does not exist in nature. Scientists believe that Native Americans living in Central Mexico developed corn more than 7,000 years ago from a native grass called teosinte or maize. Maize does not resemble modern corn. Instead the plant is filled with tiny kernels that are not closely spaced together. Corn eventually became a staple crop of Central American natives. From there it spread north into the Southwestern United States and south into Peru.