Most of the world’s flowers produce lots of pollen grains containing the male sex cells. There are different ways of making sure the pollen grains reach the ovary of a flower containing the female sex cells – the eggs.
We have recently witnessed wind pollination, whereby trees produce huge amounts of pollen to ensure that some of the pollen is blown to and lands on a female – a somewhat chancy process.
Most flowers have evolved over time to produce foods that are essential for pollinators such as insects (especially bees), birds and some mammals to survive. The flowers attract the attention of the pollinator with smell, colour of the petals, and even markings to guide the way to the nectar.
Pollen is a highly desirable and nutritious source of protein that is either deliberately gathered or is picked up accidentally on the pollinator’s body. Many flowers also produce a sugar-rich nectar which is often hidden deep in the flower in such a way that it forces the pollinator to brush past the pollen-laden anthers.
As a pollinator moves from one flower to another it carries pollen that sooner or later is deposited onto the stigma and ovary of the same kind of flower. The pollen grain germinates and carries the male nucleus down to the ovary to fuse with the egg cell. This process (cross-pollination) ensures that there is a beneficial mixing of the genetic material from different flowers of the same species.
In approximately eight per cent of the world’s flowers, however, pollen is not readily available unless it is sonicated. In these flowers the pollen is produced in tubular anthers with only a tiny opening at the tip or small slits on the side, and the pollen is only released when the anthers are subjected to vibrations of the correct frequency.
Certain bumblebees and a few native solitary bees can wrap themselves around the anthers and then contract their indirect flight muscles very rapidly at the right frequency for the pollen to be jostled and released through the tiny openings.
These vibrations are accompanied by an audible loud buzzing sound, so the process is known as “buzz pollination." Bumble bees may also bite the anthers to ease pollen release by vibrating their wings. This is known as a “bee-bite.”
The flowers that require buzz pollination often have anthers that hang down, like those found in shooting stars in our area. Other flowers in northern B.C. needing to be buzzed include some blueberries and cranberries (Vaccinium species), wintergreens (Pyrola species), tall bluebells (Mertensia paniculata) and several species of louseworts (Pedicularis species).
