Pea diminish leaf and stem growth. Adult weevils feed on the leaves and create a notched, "c-shaped" appearance on the outside of the leaves. In the mid-19th century, Austrian monk Gregor Mendel's observations of pea pods led to the principles of Mendelian genetics, the foundation of modern genetics. He ended up growing and examining about 28,000 pea plants in the course of his experiments. Mendel chose peas for his experiments because he could grow them easily, develop pure-bred strains, protect them from cross-pollination, and control their pollination. Mendel cross-bred tall and dwarf pea plants, green and yellow peas, purple and white
Franz Unger of botany at the University of Graz and also taught at the Joanneum (which became the Universalmuseum Joanneum and the Graz University of Technology); in 1850 professor of plant physiology in Vienna. In 1852 he travelled to Northern Europe and to the Orient. Unger retired in 1866 and lived on his farm near Graz. Unger was one of the major contributors to the field of paleontology, later turning to plant physiology and phytotomy. He hypothesized that (then unknown) combinations of simple elements inside a plant cell determine plant heredity and greatly influenced the experiments of his student Gregor Johann Mendel.