Pollination is the most important part of a plant’s life because it allows the plant to reproduce seeds and secures future generations of a species.
Approximately 20% of plants depend on wind or water for pollen transportation but most flowering plants (80%) are pollinated by animals, mainly insects. The pollen of wind pollinated flowers such as ragweed is usually light and dry so that it can easily be picked up and dispersed by wind. Pollen from insect-pollinated flowers such as goldenrod is oily and heavy so that it sticks to insects who provide transportation of pollen between flowers.
As flower visiting insects seek pollen and nectar, they transfer pollen form the male anther to the receptive sticky female stigma of a flower, accomplishing pollination.
Some flowers are self-fertile and can produce seed with pollen from within a single flower or between flowers on the same plant. Most plants benefit from cross-pollination though, as the mixing of different genes from various plants results in stronger species able to adapt to changing conditions. Flowers have developed a number of strategies to avoid self fertilization and encourage genetic diversity. Some of these strategies include: self-incompatibility, physical distance between male anthers and female stigmas, separate male / female plants and fertility among male and female flowers at different times.
Flowers attract pollinators by sights and smells including brilliant coloured petals and combinations of colours that direct insects to nectar. These nectar guides contain ultraviolet colour patterns that bees can see but people can’t. Flowers will also change colour at different stages of development, attracting pollinators when they need them the most. The fragrance of flowers can attract particular pollinators over long distances with their minty, sweet, or pungent smells. Flowers even have a floral electric field, meaning their negative charge combines with a bees positive charge that causes pollen to cling to the bee.
In Canada, pollinators include flower visiting insects such as bees, butterflies, moths, wasps, beetles, flies, as well as hummingbirds.
Native pollinators are keystone species meaning their contribution to the stability of ecosystems that feed and sustain all living things on Earth is vitally important.
Bees are the most important pollinator!
They are such good pollinators because:
Female bees collect protein rich pollen as the main food source for their developing offspring
They have hairy bodies that pick up and hold on to pollen
Bees usually forage on one particular nectar/ pollen plant species at a time
They visit many flowers on a single foraging trip so pollen gets transferred from flower to flower
Flowering plants and bees need each other - this reciprocal relationship
between plants and bees is simple - bees provide the movement of pollen
between plants and the plants provide nutrition and resources to them for
their help in plant reproduction. Besides being critical for growing the next
generation of plants, these seeds and the fruit which accompanies them,
are often an important food source for animals and humans.
A native bee is one that evolved right here in Canada. In Eastern Canada there are about 400 wild bee species, and about 300 of these are important pollinators. Most native bees do not have common names and live and forage unnoticed in gardens and fields. In fact, much of the pollination value that is attributed to honey bees may be due to the pollination activities of un-noticed wild bees. The honey bees we know, Apis mellifera, are relatively new to Ontario. They were imported for agricultural use, brought to North America for honey production and crop pollination. Before honey bees came to North America, Ontario’s major pollinators were native bees, who evolved with pollinating our native plants. Honey bees do not actually know how to pollinate tomato or eggplant and do a poor job with many native plants including blueberries, cranberries, cherries and pumpkins.
Other important Pollinators: Butterflies and Moths
Nectar is the primary food source for butterflies and moths. While moving around to feed on nectar, they pick up pollen grains and transfer them to other flowers. Butterfly pollinated plants often display a similar set of features. They tend to bloom during the day and to provide nectar at the bottom of a long narrow tube, which ensures the butterfly comes into contact with pollen. The flowers typically provide a large enough surface for a butterfly to land on and often have a sweet odour. The most visited flowers usually have nectar guides and are in colours that butterflies can see, usually red through violet and often ultraviolet.