Plants go through 2 prcesses pollenation and fertilisation , they are two different things and must not be confused.Pollenation is when pollen lands on the ripe stigma and fertilation is when the 2 male nuclei fuse with the egg cell in the ovary.
Cross pollenation is when pollen from another plant fertilises a plant, self pollenation is when pollen from a plant pollenates the same plant (but it may be a different flower on the same plant).Self pollenation is good when there is a steady enviroment however you run the risk of bringing 2 recessive alleles together which may be undesirable.It also reduces variation within the population which could make it harder to survive. Cross pollenation will create variation.
There are different ways for plants to be fertilised - by the wind and by plants. Wind pollenated plants will produce lots of light smooth pollen, they have inconspicuous green flowers if any no scent and…