Gynodioecious

Gynodioecy occurs as a result of transmission of nuclear (nuclear male sterility) or, more commonly, extra-nuclear (e.g. cytoplasmic male sterility) mutated alleles, which prevents pollen production, while keeping the female reproductive parts intact; other members of the species population do not inherit the mutated alleles, thus remaining hermaphrodites. In some cases, a combination of both nuclear and extra-nuclear mechanisms is observed in determining the sterile phenotype. Gynodioecy is extremely rare, with fewer than 1% of angiosperm species exhibiting the breeding system. Some notable taxa that exhibit a gynodioecious mating system include Beta vulgaris (wild beet), Lobelia siphilitica, Silene, and Lamiaceae.