Bumblebees in Pollination Biology

(3) Reduction of geitonogamy: Flower abscission for departure of pollinators
ERIKO ITO AND KIHACHIRO KIKUZAWA
Ecological Research (2003) 18,177-183

A flower falling with

a visiting bumblebee

According to Wikipedia, “Abscission” is a process by which a plant intentionally drops one or more of its parts, such as a leaf, fruit, flower or seed. So, Flower abscission means the drop of flowers intentionally by the plants.

Geitonogamy is the pollination of a flower with the pollen from another flower on the same flowering plant (Wikipedia). More geitonogamy is problematic for the flowers. It can reduce female fitness in self-incompatible plants and have the negative effects on male fitness reducing pollen export to other plants. In this way, plants especially large trees suffer more geitonogamy because of their size.

In this research, there are found that pollinators sequentially visited inflorescences within a tree and when they met with flower abortion by abscission, they were apt to move long distances and leave the tree. This observation prompts to tell that plants may utilize flower abscission as a method for regulating the movements of pollinators by disturbing them in order to prevent geitonogamy. They observed it in Tilia japonica Simonkai (Tiliaceae), a tall tree species growing up to 30 m in height.

According to them, this type of disturbance mechanism may exist in a widespread pattern in nature, but further study is required. Though, flower abscission reduces geitonogamy but it is very early to tell that it enhances a plant’s fitness.