methow grist 2011-2014 archive


Yellowbells Blush with Purpose

Insects are attracted to color. Photo by Bernie Krausse.

Anyone who has struggled with learning the scientific name of a plant can pin the blame squarely on the Swedish scientist Carl Linneaus. He came up with the idea of using two Latin or Greek words to identify any given species almost 300 years ago. For example, because of him our common little spring lily, the Yellowbell, is known to science as Fritillaria pudica.

Prior to Linneaus, people thought that flowers had been created expressly to cheer up human beings by adding a bit of color to their lives. Linneaus pointed out that what flowers were actually doing out there in the fields and forests was exchanging male and female gametes through pollen transfer — they were having sex. Europeans were horrified, and accused Linneaus of being “indecent, lascivious and lewd.” Of course it turns out that he was right, and flowers exist for the reproduction of their own species and not for the pleasure of humans.

Flowers exist to attract insects (and occasionally hummingbirds), which will pick up pollen while probing around for nectar and deliver it to another flower on another plant, thus transferring male DNA. There are three main groups of insect pollinators: 1) flies and beetles, which have very short tongues and can only pollinate small, round flowers; 2) bees and wasps, which have medium-length tongues (for an insect), up to about half an inch, and often pollinate two-sided (bilateral) flowers like lupine; and 3) butterflies and moths, whose tongues are so long they have to be coiled up like a spring (the longest insect tongue on record belongs to a sphinx moth and is 16 inches in length!).

Insects are attracted to color, but surprisingly they can’t see red very well. Thus, red flowers, like our local columbine and paintbrushes, are often hummingbird pollinated. Flowers pollinated at night are usually white, so that night-flying moths can find them. The species name for the Yellowbell is pudica, which means bashful. It is so named because the yellow flower turns red after it is pollinated. Early observers thought perhaps it was embarrassed after having an affair with an insect, but we now know that the color change is a matter of energy conservation - insects will stop visiting those yellowbells that have turned red, because they don’t perceive that color clearly. Thus they save their energy for unpollinated flowers, and both insects and flowers benefit from this full-color communication between them.

Knowing all this, we can begin to predict which flowers are pollinated by which of the three groups of insects, and which are hummingbird pollinated. Small, round flowers are pollination generalists — they are easy to land on, and any type of insect, even a fly, can reach the nectar. Bilateral flowers like lupine are usually pollinated by bumblebees, while flowers with a long spur in back to hide the nectar would have to be pollinated by a butterfly, moth or hummingbird. See if you can predict from flower color and shape what bug is dating which flower on your next walk.

Dana Visalli lives in the Methow Valley where he teaches, farms and works as a biological consultant. This was first published in his Methow Naturalist, a quarterly journal of natural history.


Have a comment?

Does anyone know if any Methow Valley flowers are pollinated by bats?

Victor Glick

Hi Victor: We have 13 species of bats in the Methow; none of them are pollinators. They are all insectivores.
It would be interesting to try to figure out why bat pollination has evolved at lower latitudes but not this far north.