Flowers, Jorge, Plants, Trees

What Is Pollination and Is It Important?

bee pollination

Pollination involves the transfer of pollen from one flower to another, resulting in fertilisation. Fertilisation is important as without plants will not produce fruit. It’s likely you don’t need to do anything to ensure pollination, as it’s probable a compatible tree will be in the vicinity. However, it is beneficial to buy a pollination partner to guarantee and improve pollination, boosting yields. 

What is pollination?

Pollination involves the transfer of male reproductive cells from a plant’s male reproductive organ to a plant’s female reproductive organ, in within there are female reproductive cells. The reproductive cells then fuse, forming a new cell, which divides rapidly eventually forming a seed. 

In plants, male reproductive cells are located within pollen cells, which are found on flowers, on the part known as the stamen. The female cells are located within the ovule, found in the ovary, which is part of the carpel. Often, both the male and female reproductive organs are found on the same flower – such flowers are known as perfect flowers – but sometimes they are not. Sometimes, male and female reproductive organs are found on different trees, known as male and female trees.

flower parts

The male reproductive cells must be compatible with female reproductive cells or otherwise fertilisation will be inhibited. Fertilisation can be inhibited if two varieties are too closely related or too distantly related. Some varieties – known as self-fertile plants – can fertilise themselves, while others – known as self-sterile plants – can’t, and therefore need to be partnered with another variety. 

As pollination is sexual reproduction, resultant offspring necessarily contain information from both male and female reproductive cells. Therefore, the seeds of any fruit will be of a different variety than that of the parent. (This is true even in the case of self-fertilisation, because of genetic recombination and Mendel’s law of segregation.)

Most plants, including most fruit trees, rely on insects, primarily bees, to transfer pollen between flowers, but some rely on the wind. 

walnut flowers
The male and female flowers of a walnut. Walnuts rely on the wind for pollination. Picture credit: Dalgial licensed under CC BY-SA 3.0.

What we are interested in is not fertilisation, but the production of fruit, which unfortunately, most trees will not bear without fertilisation. This is because fleshy fruit develops from the ovary, which encloses the ovules that form seeds.

Do I have to worry about pollination?

If you live in an urban area, it’s probable there will be another compatible tree in the vicinity, and as bees forage for miles, there is a high chance of pollination. If you live in an isolated location, where you can’t be certain of another compatible tree, it might be best to buy a pollination partner.

Now, just because you live in an urban area, it doesn’t mean there is no benefit to buying a pollination partner, which will not only guarantee pollination, but help improve pollination. You can tell if a plant has been poorly pollinated, if it’s fruits are small, misshapen and have few seeds.

Low temperatures impede pollination as frost can damage blossoms, which will fail to turn into fruit. Early flowering stone fruits, such as almonds and apricots, are especially vulnerable, and the former will not reliably crop in the UK. As bees will not forage when it is cold or windy, bad weather impedes pollination also.

fruit trees flowering timeline

As pollination is primarily carried out by bees, it’s necessary that insects can access your flowers. It’s also necessary that two varieties flower in the same period. Hence, why trees are put into flowering groups, with any variety being able to pollinate another in +-1 flowering group. Flowering groups are preferred to specific dates, as plants will flower at different times in different parts of the country. A variety in flowering group 1 will always flower before a variety in flowering group 2.

apple pollination groups

pear pollination groups

cherry pollination groups

Unfortunately, even if a plant is in the same flowering group, it doesn’t mean pollination is guaranteed, due to genetic incompatibility. Cherries are notorious for this, so it’s always best to buy a self-fertile variety. Triploids, such as Bramley, are sterile and are unable to pollinate other species. So, if you want a triploid, it’s necessary to partner with two non-triploid varieties. 

Different species can sometimes pollinate one another. Famously, crabapples can pollinate apples, and are often used as part of an orchard to help with pollination. Ornamental cherries, however, can’t pollinate cherry fruit trees. 

cherry and apple pollination compatibility diagram

Jorge at PrimroseJorge works in the Primrose marketing team. He is an avid reader, although struggles to stick to one topic!

His ideal afternoon would involve a long walk, before settling down for scones.

Jorge is a journeyman gardener with experience in growing crops.

See all of Jorge’s posts.

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