Wild Blue Indigo and Bumblebees

June is a blue month in our garden. And perhaps my favorite blue flower for June is the Wild Blue Indigo (Baptisia australis). This is such a great plant: it’s beautiful, tough, and low-maintenance. Give it time and it will create a substantial presence, around four feet tall and wide.

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I love the color and shape of Wild Blue Indigo flowers, which is suggestive of its membership in the Pea family (Fabaceae). Like other members of this family, Wild Blue Indigo enriches the soil with nitrogen.

DSC_0564While Wild Blue Indigo is in bloom, it’s fun to watch the Bumblebees foraging on the flowers. It turns out Baptisia flowers are shaped to provide access to Bumblebees while denying entry to competing pollinators.

DSC_0684Bumblebees grip the “keel” of the flower with their mid and hind legs. The keel is formed by two fused petals that curl around the flower’s reproductive parts.

DSC_0571They use their grip on the keel to leverage themselves between the lower part of the flower and the upper petal, or banner. Once this is done, they can access the nectar. Other pollinators generally lack the size and strength to accomplish this maneuver.

DSC_0685Bumblebees start with the bottom flowers and work their way to the top. In the process, they access nectar and pollinate the blooms closer to the top of the flower spike.

 

DSC_0580For more information on Baptisia and Bumblebees, check out this post on the blog of the Xerces Society for Invertebrate Conservation.

Which plants in your garden attract the most Bumblebees?

31 Comments on “Wild Blue Indigo and Bumblebees”

  1. I love Baptisia and your photos of the bumbles gaining access are wonderful. For us, however, rhododendrons are the biggest bumble bee feeding stations. The honey bees avoid the rhododendrons, but the bumblebees adore them.

  2. I’ve had a Baptista for several years now, and it has never bloomed. I think it doesn’t have enough room, and maybe doesn’t get enough sun. I’m tempted to get another and try it somewhere else. How does the plant hold up through the summer after it’s done blooming? Does it stay green and nice, or does it start to die back pretty quickly?
    As for bees, I’ve seen a lot around my Nepeta, Spirea, and even in the now spent blossoms of the rhododendron. Later the Russian Sage will be full of them!

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