Extra Floral Nectaries

Why are nectaries found in places other than flowers?

Nectaries can be found on parts of plants other than flowers and in this case have no connection with pollination. At least 2000 different species in 64 families have been identified as having extra floral nectaries so they are very common plant structures.

Bracken (Pteridium aquilinum), Guelder Rose (Vibernum opulus) some cherry species (Prunus spp) Bay laurel (Laurus nobilis) and field beans (Vicia faba) all have extra floral nectaries that are commonly exploited by honeybees.

The generally accepted theory for the extra floral nectaries, apart from helping to maintain the balance of water and sugars within the plant, is as a defence mechanism. Extra floral nectaries are attractive to ants, which will protect an otherwise vulnerable plant from grazing animals that would eat the leaves. There are many unanswered questions about extra floral nectaries which underline the complexity of the relationship between plants and insects.

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

Celia Davis is the author of two fascinating books published by Bee Craft with more details about the place of the honeybee in nature. The Honeybee Inside Out and the The Honeybee Around And About. Available from the BeeCraft shop