What is pollination?

Pollination is an essential ecosystem service that allows plants to reproduce. In a flower, pollination occurs when the stamen (the male part) produces pollen that is transferred to the stigma (the female part) and taken to the ovule where the pollen fertilises the ‘eggs’ that will grow into seeds.

There are two main methods of pollination: self-pollination and cross-pollination. Self-pollination is when pollen grains fertilise the same flower it originated from. Whereas, cross-pollination is when pollen from one flower is transferred to a different flower, which can occur via insects, birds, mammals, wind, people, and water.

How Cross-pollination Occurs

Cross-pollination is only possible with a vector to transfer the pollen from one flower to another. These vectors include insects, birds, mammals, wind, people, and water. Some of these vectors are referred to as ‘pollinators’.

Bees are one of the most well-known pollinators, and others include butterflies, hoverflies, and wasps. Flowering plants attract pollinators by producing nectar, which is a sweet liquid that pollinators consume. Honeybees collect nectar to make honey. Whilst visiting the flower, pollen from the stamen will stick to the pollinator and transported to another flower where it lands on the ovule and allows fertilisation to produce new seeds.
Click to see what plants flower at different months through the year.
Wind pollination is called anemophily and allows for cross-pollination over larger distances than insect pollinators. Grasses have adapted to rely on wind pollination. In addition, trees that produce catkins -which are long clusters of small flowers without petals- and trees that produce cones rely on wind pollination.

Small mammals (including squirrels, shrews, and harvest mice) passively pollinate plants, meaning they do not display any particular behaviour to collect pollen, and instead the pollen will stick to their fur and land on a different flower when they walk past.
Click here for more information about catkins

The Importance of Pollinators and Cross-pollination?

In the UK, there are around 6000 species of insect responsible for pollinating crops and wild plants, and they contribute to more than £500 million a year to UK agriculture and food production. Therefore, pollinators are essential to perform cross-pollination and the benefits are explained here.

For plants to produce fruit successfully, their flowers need to be pollinated. For example, apples rely on cross-pollination to grow. Once the blossom flowers have been pollinated, the seeds will start to grow. As the seeds develop, petals from the flower falls off and the ovary (apple core) starts to grow. The outer layer of the apple that surrounds the ovary, which is known as the ‘exocarp’ and is the edible part of the apple, then continues to grow.

Taking the example of the apple and applying it to other crops shows how important cross-pollination is for agriculture and food security both in the UK and globally because it allows crops to reach their full yield potential, improves genetic diversity, and improves the quality of the fruits.

Furthermore, cross-pollination is vital for supporting ecosystems. Flowers need fertilising in order to make the seeds needed to grow new seedlings and colonise new areas. Without this process, ecosystems would eventually cease to exist as old plants die and there are no new plants to replace them.

Plus, without pollination, trees and hedgerows cannot grow the berries that are essential for birds including blackbirds, mistle thrush, and greenfinches. Furthermore, pollinators themselves provide a good food source for a variety of garden birds. These birds build nests, and their eggs provide food for birds of prey, foxes, badgers, and other predators. Therefore, it is clear that pollinators are vital for supporting the food chain.

Threats to Pollinators

Unfortunately, there are a variety of threats to bees and other pollinators across the UK which are listed here:

  • Habitat loss – hedgerows, woodlands, wildflower meadows and other important habitats that insects rely on are being lost across the UK.
  • Heavy use of pesticides – the intensification of agriculture has led to an increase in pesticide use which negatively impacts pollinator populations.
  • Parasites and disease – honeybees have been introduced to the UK from Europe, and with them have passed on pests and diseases to the UK’s wild bumblebees.
  • Climate change – the extreme weather associated with climate change alters normal seasonal timings and impacts pollinator’s food sources and nesting behaviour.
  • Invasive species – invasive species are not native to the UK and cause damage to the environment. For example, the Asian Hornet can kill a beehive in a matter of hours. They have been wreaking havoc in Europe and have been sighted in the UK, but there are strict regulations to destroy any nests.

DEFRA (the Department for Environment, Food, and Rural Affairs) is a government department to protect the environment. It recognises the importance of and threats to pollinators in the UK and created action plans to help boost populations since 2014.

Click here to read the most recent action plan.

How to Help Pollinators

Everyone wants to see more bees, butterflies, and other insects in their gardens; especially knowing that they are working to sustain our ecosystems and food production. There are a few things that you can do to help these wonderful creatures:

  • Build insect hotels of any size that provide shelter and nesting spaces for pollinators.
  • Stop using pesticides in your garden. Some ‘pests’ are a food source for pollinators and birds.
  • Grow bee-friendly flowers. These include nectar-rich wildflowers like foxglove, bird’s-foot trefoil, and red clover.
  • Complete Flower-Insect Timed (FIT) counts and record your findings on the FIT App to contribute to the UK Pollinator Monitoring Scheme.
Read more about this topic here

In Summary

Overall, pollination is vital for the reproduction of plants, with a lot relying on cross-pollination to produce seeds and fruit. Pollinators are essential for cross-pollination however, there are a variety of threats to their survival (such as habitat loss, climate change, and pesticides) which could bring negative impacts to agriculture and ecosystems. Therefore, it is important that everyone does their bit to protect pollinators by planting bee-friendly flowers, creating insect hotels, and completing FIT counts.

Trustgreen Projects

If you want more information on projects Trustgreen have organised to benefit trees and wildlife have a look at the promoting wildlife conservation article on the community stories page on our website.

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Community stories

Residents are central to everything we do at Trustgreen. Over the years we’re proud to have hosted many wonderful community engagement projects which continue to have a long-lasting impact on the people who live within those communities.

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