Why cross pollination

Most plants that bear flowers reproduce through sexual reproduction. This means each seed comes from an ovule of the mother plant that was fertilized with pollen from a male plant.

These special reproductive cells, called gamete, are produced and released in flowers. Cross-pollination is what happens when each gamete comes from different varieties within a plant species. Many species are capable of producing both male and female gametes on the same plant , sometimes even on the same flower. Sometimes two different species within a family can bear fruit together and will have offspring.

This is called hybridization or hybridizing, and the offspring is called a hybrid. In a way, hybridization is a successful cross-pollination between two different species. In most cases, cross-pollination increases the harvest in number and fruit size. Lastly, in some cases cross-pollination is completely unnecessary , or should even be avoided. Many fruit tree varieties require cross-pollination to bear the most fruit, but some absolutely require it.

Indeed, on their own or if only planted with the same variety, they would never bear any fruit. Fruit tree varieties that absolutely need cross-pollination to bear fruit :. Almost all varieties and species will bear a larger harvest if they are cross-pollinated with other varieties. This is especially true for most self-pollinating varieties.

Although they will bear fruit without any outside pollen, there are still advantages of cross-fertilizing them:. Most self-pollinating varieties will bear fruit perfectly without any pollen from other varieties: their own pollen is enough. This is called parthenocarpy. Fruits would stay small and branches may break off. In the process of cross pollination , the pollen is transferred from one plant to another by a pollinator, such as an insect, or by the wind.

Most plants use cross pollination. Those that use insects as pollinators tend to have brightly colored flowers and an attractive scent. Those that are pollinated by the wind have long stamens and pistils with small or no petals. Plants that use self pollination, such as peanuts, tend to have smaller flowers. Some plants that cross pollinate are also capable of self pollination if cross pollination is unsuccessful. These include peas, orchids and sunflowers. Examples of plants that use insects for cross-pollination include apples , plums, pears, raspberries, blackberries, blackcurrants, strawberries, runner beans, pumpkins, daffodils, tulips, heather, lavender, and most flowering plants.

Examples of self-pollinating plants include wheat, barley, oats, rice, tomatoes, potatoes , apricots and peaches. Many plants that are capable of self-pollinating can also be cross pollinated.

Cross pollination is advantageous because it allows for diversity in the species, as the genetic information of different plants are combined. However, it relies on the existence of pollinators that will travel from plant to plant. Self pollination leads to more uniform progeny, meaning that the species is, for example, less resistant as a whole to disease. However, it does not need to expend energy on attracting pollinators and can spread beyond areas where suitable pollinators can be found.

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