Pollination and human food security

Inside a flower

Select a part, or switch to ‘Petals off’.

The petals sit around the male and female parts.

Select a part to see what it does. Peel the petals off to see what is underneath.

What you need to know

• Plants are producers: they make their own food, and every consumer, humans included, depends on that. Yet plants rely on animals too.
• Anthers make pollen, the sticky stigma collects it, and seeds are made in the ovules inside the ovary.
• Have a goYour friend points at a flower’s sticky tip and says, ‘That’s where the pollen gets made.’ Right or wrong?

  Wrong. The sticky tip is the stigma, which collects pollen.

  Pollen is made in the anthers; the stigma is sticky so that it can catch pollen when it arrives.

• Pollination means moving pollen from the anthers to the stigma of the same type of plant, so seeds can be made.
• Insects are drawn in by petals, fragrance and sugary nectar. Pollen sticks to their body, then to the next flower’s stigma.
• Wind-pollinated plants, such as grasses and wheat, have no colourful petals. Their anthers hang outside, releasing millions of light pollen grains.
• Have a goGrass has no colourful petals, so it isn’t advertising to anything with wings. How does its pollen get to the next flower?

  On the wind, as millions of light pollen grains.

  Wind-pollinated plants such as grasses release huge amounts of light pollen that the wind carries, rather than relying on insects.

• Fertilisation comes after pollination: genetic material from the pollen combines with the ovule’s. Fertilised ovules become seeds, often inside protective fruits.
• Seeds matter: rice, maize and wheat are seed crops, and they make up 51% of the food eaten across the world.
• Many crops depend on insects, especially bees, to be pollinated, and only pollinated crops can produce seeds and fruits.
• Have a goThe bees go on strike. A crop that depends on bees flowers beautifully, but not one bee visits. Seeds and fruits, or none?

  None. Only pollinated crops can produce seeds and fruits.

  A bee-dependent crop needs a bee to carry its pollen; with no pollination there are no seeds or fruits, however good the flowers look.

• Bees and other pollinators have declined in the past 50 years, because of habitat destruction, introduced pests, diseases and insecticides.
• Less pollination means less food while demand rises, so conserving pollinators (hedgerows, wildflowers, less insecticide) helps food security.

The big picture

Seeds and fruits only form after pollination, and many of the crops we eat depend on bees to be pollinated. Habitat destruction, introduced pests, diseases and insecticides have cut pollinator numbers, so fewer crops make seeds and fruits and there is less food while demand rises. That threatens food security, and conserving pollinators helps to protect it.

⚠ Watch out

Treating pollination and fertilisation as the same thing. Pollination is only the pollen arriving at the stigma. Fertilisation comes after it, when genetic material from the pollen combines with genetic material in the ovule.

Memory hook

Land, join, grow: pollen lands on the stigma (pollination), its genetic material joins the ovule (fertilisation), and the ovule grows into a seed.

Check yourself

Explain to a friend why a farmer who grows bee-pollinated crops might care about a hedgerow full of wildflowers. Use at least four links in your chain, and say which ones depend on the bees.