Mendel did many experiments using pea plants. He cross pollinated and self pollinated them to see what the result would be. there is a lot of variation among pea plants, and he wanted to see what type of plant would produce what type of plant. The variations of the pea plant include height, seed shape, seed color, flower color, and some other things. It is believed that Mendel used about 28,000 pea plants during the course his research. He discovered that some traits are dominant and some are recessive.