Mendel conducted hybridisation experiments on garden peas and investigated seven pairs of contrasting traits . Table 4.1 in the text explicitly lists these 7 characters: Stem height, Flower colour, Flower position, Pod shape, Pod colour, Seed shape, and Seed colour . While there were 14 true-breeding pea plant varieties selected (representing the two opposing traits for each of the 7 characters) , the number of characters themselves was 7.