In 1856 Mendel began his experiments on plant hybridization with garden peas in the monastery garden. Although similar work had already been done by contemporary botanists, the significant features of all these experiments had been overlooked because the investigators made overall observations of all inherited characters instead of collecting and analyzing data in a systematic, mathematical way. This is how Mendel achieved what his predecessors could not. First of all he concentrated his attention on a single character in his experiments on inheritance. Secondly, he kept accurate pedigree records for each plant. And third, he counted the different kinds of
plants resulting from each cross. Fourthly, he analyzed his data mathematically.
Mendel’s success is in part also attributed to his choice of material. The garden pea (Pisum sativum) used in his experiments offers certain advantages: it is an easily growing, naturally self fertilizing plant; it is well suited for artificial cross pollination therefore hybridization (crossing of two different varieties) is easily accomplished; it shows pairs of contrasting characters which do not blend to produce intermediate types and can be traced through successive generations without confusion. For example tall and dwarf are a pair of contrasting conditions for the character height; similarly round and wrinkled seeds are contrasting forms for the character seed texture. On self pollination each character breeds true. Mendel worked with seven pairs of characters so that he had 14 pure breeding varieties.