Snapdragons and Bumlebees by Marea Reinicke

Many flowers depend on pollinators to help them spread pollen for fertilization. The snapdragon has unique ways of inviting the 'right' kind of pollenators(bumblebees) to it by scent, color and physical form. During the day when bumblebees are most active, snapdragons release four times more scent than at night. This scent atracts many pollinators, including bumble bees.If the flower isn't ready for pollination (not mature) it does not release as much scent so that pollinators are not atracted to them. When a bumle bee does land on the flower, the scent (which is only on the lobes of the petals) is carried back to the hive, attracting more bees to the plant.(Purdue News,p2)

The colors of snapdragons are not coincidental. Bees cannot see red, yet do see yellow, blue and ultraviolet. Because of this, snapdragons (along wih other bee-pollinated flowers) are mostly yellow (some blue) with ultraviolet nectar guides or "landing patterns" that attract and help a bee orientate its landing. (Polonation and Plant Families,p2.)

The sturdy, irregualr bell-shape of the flower also designates what kind of pollinator may have access to its nectar. The bell-form fits the shape of a bumle bee's body so that when it enters the close-quarters of the flower "the pollen sticks to the 'fur' of the bee or else the bees collect the pollen in specially-modified areas on their legs".(Pollination and Plant Families,p2. ) This pollen is then carried with the bee as it goes to collect more pollen from other flowers. To help insure that the pollen is 'collected' when its nectar is gathered, not ever insect can collect nectar from a snapdragon. "...Snapdragons are designed for a bumblebee of just the right weight to trip the opening mechanism."(Coevolution and Pollination p2.) Other insects which are too small or too heavy, cannot trigger the opening to gain access to nectar which lie on the other side of a small, narrow floral tubes.

Photo from website

Photo of bee entering snapdrangon from Purdue News, Undrestanding of floral scents blossoms in Purdue laboratory Photo of snapdragon plants from link

NDSU

References

Coevolution and Pollination( p2.)

Pollination and Plant Families (p1-6)

Purdue News - Understanding the floral scents blossoms in Purdue laboratory (Aug. 2000)(p.1-5.)

Snapdragon Pollination (p1-2.)