Weigela Flowers Change Color To Increase Pollination

Did you guess what the bumble bees were doing in the post earlier this week?



It seemed like the bees were only visiting the light-colored flowers and were ignoring the dark pink ones.

A little research confirmed this for another species, Weigela middendorffiana. According to Ida and Kudo, the flowers change color from yellow to red inside as they age. This species also is pollinated by bumble bees and the bees ignore the older, red flowers. The color-changed flowers did not provide a nectar reward. The authors suggest the color change may increase pollination success by reducing successive visits to the same flower.

Lupines and lantana also change color after pollination. Do you know of any other plants that do this?


Ida T.Y, and G, Kudo. (2003). Floral color change in Weigela middendorffiana (Caprifoliaceae): reduction of geitonogamous pollination by bumble bees. Am J Bot. 90(12):1751-7. (full text)

What Bumble Bees Can Tell You

Check out this shrub I discovered during a recent visit to western New York.


It had pink tubular flowers and variegated leaves.


It appears to be a Weigela, perhaps Weigela florida ‘Variegata.’


The flowers varied in color from basically white to very dark pink.


Although the flowers of other species of plants in the area were visited by a variety of insects, it was immediately apparent that these flowers are particularly attractive to bumble bees. There might have been a carpenter bee or two as well, but basically large, robust bees.


Regardless of the fact it was overcast, windy and raining at times, the bumble bees continued to visit.


Watching the bumble bees, I began to see a pattern.


Did you spot it right away?


Turns out that what I noticed has been verified in another species of Weigela.

Do you see the pattern I noticed? Let me know what you think it is.


Edit:  The answer is now posted.

Cactus Flower Pollination and Pollinator Week Events

Did you know that this week is Pollinator Week?

If you live in Arizona, you might want to check out the National Pollinator Week celebration at Tohono Chul in Tucson. It is going to be from 10 a.m. to 4 p.m. on Saturday June 22, 2013. The first 50 families attending the event will get to make their own native bee habitat to take home. There will be special showings of Wings of Life, a new film from Disneynature narrated by Academy Award winner Meryl Streep, and a talk by bee specialist Dr. Stephen Buchmann of Pollinator Partnership. Sounds like a great way to spend the day!

If you don’t live in Arizona, you can find your state on the clickable map at www.pollinator.org to locate events near you.

When talking about pollinators, we often hear that they are responsible for the viable production of about one third of our food supply. Although we think of grocery store staples like apples, squash and almonds as foodstuffs that require pollination, cactus fruit – or “tunas” as they are also called – are another source of food that requires pollinators.


It is almost impossible to look into a cactus flower and not find a bee. Most of them are covered with copious amounts of pollen.


The flowers of the cactus genus Opuntia even have a special mechanism that causes the stamens to move when they are touched. You can see it in action in this video.

The movement of the stamens is thought to add more pollen to any pollinators that enter the flower.


A layperson might say it’s almost like the bee is getting a “hug” from the flower.


The end result is that the flowers are pollinated and produce lovely red fruit that make delicious jelly and syrup.

Even if they aren’t consumed by humans, some 75% of flowering plants need an animal to carry pollen from flower to flower. Pollination is an incredibly important service that we need to be aware of and support.

What are you doing to celebrate pollinator week?
Wings of Life is also available on DVD/Bluray.

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