hybridization
Mendel first worked with plants that differed in a single characteristic, such as flower color. A hybridization is a cross between two individuals that have different traits. A hybridization in which only one characteristic is examined is called a monohybrid cross . The offspring of such a cross are called monohybrids. Mendel noted that hybridizing true-breeding P generation plants gave rise to an F 1 generation that showed only one trait of a characteristic. For example, a true-breeding purple-flowering plant crossed with a true-breeding white-flowering plant always gave rise to purple-flowered hybrid plants. There were no white-flowered hybrids. Mendel wanted to know what happened to the white-flowers. If indeed a "heritable factor" for white-flower had disappeared, all future offspring of the hybrids would be purple-flowered - none would be white. To test this idea, Mendel let the F 1 generation plants self-pollinate and then planted the resulting seeds.