In which family of plants do pollen grains maintain viability for months?

All of the above

The correct answer is Option (4) → All of the above

When once they are shed, pollen grains have to land on the stigma before they lose viability if they have to bring about fertilisation.  The period for which pollen grains remain viable is highly variable and to some extent depends on the prevailing temperature and humidity. In some cereals such as rice and wheat, pollen grains lose viability within 30 minutes of their release, and in some members of Rosaceae, Leguminoseae and Solanaceae, they maintain viability for months. It is possible to store pollen grains of a large number of species for years in liquid nitrogen (-196^oC). This means that even after being released from the anthers of the flower, the pollen grains remain capable of fertilizing the ovules for an extended period of time. Such stored pollen can be used as pollen banks, similar to seed banks, in crop breeding programmes.

Overall, the ability of pollen grains in Rosaceae, Leguminoseae, and Solanaceae to maintain viability for months enhances the reproductive strategies of these plants and allows them to adapt to varying pollination conditions, ultimately ensuring their reproductive success and survival.