When you go to the supermarket, there are lots of different apples that you can buy; Red or Golden Delicious, Granny Smith, McIntosh, just to name a few.

Each variety of apple has a different shape and color, and a different flavour.

Did you ever wonder where apples come from or how an apple tree makes apples? Actually, apples start as flowers on the apple tree. Without the help of bees though, the flowers would bloom and then wither and drop without ever having a chance to become an apple.

For a flower to become an apple, the pollen that is produced by the flowers on one apple tree must be transferred to the flowers on another tree. The pollen is moved between trees by bees who visit the flowers to collect nectar and pollen. Moving pollen between flowers is called cross-pollination.

One of the most important questions concerning cross-pollination of apple flowers is the way that bees move pollen between trees. When a honey bee finds an apple tree that has thousands of flowers on it, the bee will stay on the same tree to collect nectar and pollen.

If most bees stay on the same tree, how does pollen get moved between different trees so that cross-pollination occurs and apples can develop?

What was discovered is that honey bees can spread pollen to other bees in the hive. If you ever watched honey bees in a hive, you would see that they touch one another almost constantly. If part of the honey bees in a hive are visiting Granny Smith apple trees and part are visiting Red Delicious trees, there is a good chance that both types of pollen will be on the bodies of most bees in the hive. Cross-pollination can occur when a honey bee that has Red Delicious pollen on its body that it obtained from other bees in the hive, is visiting Granny Smith flowers. The Red Delicious pollen will be deposited on to the first few Red Delicious flowers that the bee visits, and those flowers will have a good chance of becoming apples.

This is how plants and bees help one another. The plants make flowers that have nectar and pollen that the bees need for food.

Pollen must be transferred between flowers for the plant to produce fruit and seeds so that new plants can be made. The pollen is transferred by bees while they collect the nectar and pollen.

We also benefit from the relationship between bees and flowers because without it, we would not have apples or many other fruits and vegetables that we enjoy eating every day.

By Dr. Gloria Hoffman, USDA Scientist, Carl Hayden Bee Laboratory

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