Gregor Mendel's observation on hybridization in Pisum

    Mendel took as his parental lines (P) two pure-breeding lines of garden peas (Pisum sativum) that differed in a single character (coat colour), which existed in one or the other of two phenotypes (yellow or green). When the two lines were artificially crossed, the offspring were invariably yellow. When these first filial generation (F1) plants were crossed, seeds of both colours were observed in the F2 generation. Mendel's scientific insight was to count the relative proportions of the two phenotypes: he found that they always occurred in a 3:1 ratio, with the F1 phenotype predominating.

Figures ©2002 by Griffiths et al.; all text material ©2014 by Steven M. Carr