Mechanism Favouring cross-pollination Although cross-pollination requires the production of large amounts of pollen has the advantage of increasing the amount of grains, it genetic union of the gametes with their different combinations of chromosomes could result, for example, in a particular combination of chromosomes which could give the offspring resistance to a particular disease. Many plants have mechanisms which favour cross- pollination. These mechanisms include: being dioecious where self-pollination is impossible(e.g. papaya), or monoecious where the chances of self-pollination are reduced(e.g. mango); having the anthers and stigmas mature at different times, having substances which inhibit either pollen penetration of the stigma or growth of the pollen tube down the stigma of the same plant(e.g. orchid); and