Sunday, September 1, 2013

Buzz Pollination of Fabaceae Flowers

Flower of Senna. Observe the pores at the tip of the anthers
© Beatriz Moisset
It is interesting how several families of plants have evolved anthers that require buzz pollination, also called sonication, independently of each other. The organ that contains the pollen or anther of most flowers splits open when the pollen is ripe, making it available to the flower visitor. Buzz pollinated flowers do it differently. The anther remains closed, except for a pore at its tip. The only way to extract the pollen is by shaking the anther with just the right kind of vibration. Bumble bees are pros at doing this. Honey bees never developed the technique.

Close-up of the anthers © Beatriz Moisset
We are most familiar with the members of the tomato and potato family, Solanaceae. So much so, that some gardeners resort to a tuning fork or just an electric toothbrush to ensure pollination of the tomato flowers. Seeing pollen fly from the anthers during this process is a sight worth seeing. Another family with members that require buzz pollination is the Ericaceae; Blueberries, cranberries, azaleas and rhododendrons use this process.

Senna plant. © Beatriz Moisset
Perhaps, it is less known that some members of the pea family, Fabaceae, in the Caesalpinioideae subfamily also resort to this process. The genera Senna and Cassia, belong to this group. Recently I observed a bumble bee visiting the bright yellow flowers of a Cassia and was able to record the buzzing. The sound is unmistakable, quite different from the buzzing of flying. Watch the video of bumble bee on Senna and pay attention to the sound. You can compare it to that of a bumble bee pollinating an azalea.

Bumble bee, probably the common bumble bee. © Beatriz Moisset

List of Articles

Beginners Guide to Pollinators and Other Flower Visitor

© Beatriz Moisset. 2013


  1. I didn't see the video, but enjoyed the article. I have two Wild senna plants, and I'm glad they've both had lots of bumble bees on them.

  2. I'm so glad that you linked the video! I've heard that higher pitched buzzing, but didn't realize what I was hearing - I just thought that the bee was getting irritated at not getting enough pollen or nectar from the flower! Great post, as always.

  3. I came back and found the link to see the video. Yes, I've heard that wonderful sound here as well.