Carl Erich Correns (1864-1933) is remembered in the annals of science as one of the three botanists who re-discovered Mendel's laws. He can also, however, be regarded as one of the founding figures of classical genetics in Germany. Between 1894 and 1899 he carried out the crossing experiments with corn and peas that led to the re-statement of Gregor Mendel's (1822-1884) results. Between 1900 and 1910, he explored the complications of these laws, including the coupling of factors due to their chromosomal location and the inheritance of sex, in a great number of plant species. In later years Correns became interested in and experimented on phenomena of extra-nuclear inheritance.