<P> The primary mechanism used by flowering plants to ensure outcrossing involves a genetic mechanism known as self - incompatibility . Various aspects of floral morphology promote allogamy . In plants with bisexual flowers , the anthers and carpels may mature at different times , plants being protandrous ( with the anthers maturing first ) or protogynous ( with the carpels mature first ) . Monoecious species , with unisexual flowers on the same plant , may produce male and female flowers at different times . </P>
<P> The primary mechanism used by flowering plants to ensure outcrossing involves a genetic mechanism known as self - incompatibility . Various aspects of floral morphology promote allogamy . In plants with bisexual flowers , the anthers and carpels may mature at different times , plants being protandrous ( with the anthers maturing first ) or protogynous ( with the carpels mature first ) . Monoecious species , with unisexual flowers on the same plant , may produce male and female flowers at different times . </P>
different maturation time of androecium and gynoecium in the same flower is
different maturation time of androecium and gynoecium in the same flower is
self - incompatibility protandrous ( with the anthers maturing first ) protogynous ( with the carpels mature first )
self - incompatibility protandrous ( with the anthers maturing first ) protogynous ( with the carpels mature first )