Plant reproduction involves two major parts of the plant – the stamen which is the male part of the flower and pistil which is the female part of the flower. For reproduction to occur, any plant must have pollen producing stamens and egg containing pistils. Pollination can occur in many ways – with the help of winds, birds or even animals. Depending on whether the male part and the female part are present in the same plant or different plants, we can classify the plant species as monoecious or dioecious.
Plants like tomatoes, peaches, apricots have so called perfect flowers that contain both male and female parts. A slight breeze could accomplish the task of pollen falling from the male part to the female part. These plants could therefore be called as self-fruitful.
There are certain plants like apples, pears, cherries and plums that will not accept the pollen from their own flowers. These plants need pollen from other nearby source and hence referred to as non self-fruitful plants.
Corn, cucumber, walnuts are known as monoecious plants. Monoecious species have separate male and female flowers on the same plant but on different parts. The tassel which provides the pollen is the male flower while the silk on corn is the female.
There is yet another kind of plants which includes the persimmon trees, date palms and hollies that have only the male part or female part. Such species of plants are called dioecious species. Presence of both male and female plants is required for pollination to occur. At least two of such trees have to be planted for attractive berries to be produced.