Bee Bistros

Why do plants secrete nectar anyway ?

Beekeepers like to think they know all about this. Simple. Flowers produce nectar for our bees to turn into honey (for us to eat!) and the bees pollinate the flowers in return. But why did flowers start to produce honey in the first place ? And how is it produced ?

Why produce nectar ?

Plants may have started producing nectar to control the concentration of their plant sap. In any biological system the concentration of fluids in the organism must remain fairly constant or the system will be upset. In an actively growing plant sugar may be produced faster than it can be used. Alternatively, it may be the water that needs to be controlled. In spring, rapid root growth pushes lots of water into the plant and the excess escapes through structures called hydathodes located at the ends of the water carrying tubes. This process is known as guttation.

If a plant can attract a pollinator and this mutual co-operation increases the both parties’ chances of survival, then nectar production gives a selective advantage to the plants that do it best. And more seed production leads to more offspring from that plant.

How is nectar produced ?

The nectaries are well defined, but microscopic glandular organs that secrete nectar by actively extracting sugars and other substances from the plant sap and passing them to the outside of the plant. They are often surrounded by hairs and are normally found at thebase of a flower. The cells of the nectary draw water and dissolved substances into them either through small holes or the cell membranes resulting in a pool of nectar ready for collection.

Some nectars are harmful to the bees, which seems a bit of an own goal. The best known of these are certain non-native lime trees, which can cause the bees to fall unconscious from the flowers. Bumblebees seem to be worst affected. Maybe honeybees have more sense.

Abstracted from an original article Bee Bistros by Celia Davis NDB Beecraft October 2005

Celia Davis is the author of two fascinating books with intimate details about the place of the honeybee in nature. The Honeybee Inside Out and her latest book The Honeybee Around and About. Both are published by Bee Craft and available from the Beecraft shop