What happens when more than one grain of pollen enters a stigma?

Question

what about when more than one grain enters the stigma?

Answer 1

Generally pollen from other species do not grow on the flower. There are some factors that inhibit their growth.

If pollen from same species lands on the stigma, self pollinated pollen is not preferred. Generally the 'other' pollen grows better, by way of faster formation of pollen tube in the style and so on. This is because nature always looks for cross pollination which is given precedence. New genes and more heterogeneity ensures better survival.....

But in some families like Asteraceae, selfing is the rule. No wonder....it constitutes one of the largest families......

Answer 2

Perhaps double fertilization occurs. This second link you have to scroll about one-third of the way down. The first link click on the words double fertilization in the tab or scroll halfway down.

Answer 3

Each pollen grain carries a variety of nutrients and upon arrival at the stigma it divides into several cells and grows a tube through the often very long stigma of the flower. Growth continues to the embryo sac in the ovarium of the flower, inside which one egg cell will fuse with a sperm cell from the pollen and complete the fertilization. Depending on the requirements for this process and the mode of transport from one flower to the next, i.e. insects, water or wind, each species of plants has evolved a characteristic pollen type. Thus, the pollen grains from most species can be distinguished by their outer form and/or by their chemical composition or content of nutrients. The knowledge of this is used in the identification of paleontological discoveries (paleopalynology) and in the identification of geographic and botanical origin of honeys (melissopalynology).