Photo of the Week – May 2, 2013

As I wrote in an earlier post, my boys and I were at our family prairie last weekend.  Only three flower species were blooming.  One of those was ground plum (Astragalus crassicarpus, aka buffalo pea), and I took several photos of the flowers as I walked around.  This one was taken as the boys were waiting impatiently for me to get in the truck so we could get home for lunch.  As it turned out, the photo turned out to be my favorite of the day, and the boys didn’t starve.

Ground plum flowers at the Helzer prairie near Stockham, Nebraska.

Ground plum flowers at the Helzer prairie near Stockham, Nebraska.

Besides being an attractive flower in the early spring, ground plum also produces large edible pods that taste like raw peas when they’re still green.  Those pods grow to about an inch in diameter, and resemble plums – especially when they turn red later in the year.

I haven’t yet figured out why ground plum plants that flower in the spring don’t always produce pods.  We had one seed harvest year (2001) in which we collected a 30 gallon barrel full of seed pods from one 60 acre prairie, but I have never seen that kind of production since.  Most years, we do a lot of searching but find little seed – even where we know plants were blooming prolifically in the spring.  I assume it’s a combination of weather, management, and herbivory pressure, but that doesn’t really narrow it down much!

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About Chris Helzer

Chris Helzer is the Director of Science for The Nature Conservancy in Nebraska. His main role is to evaluate and capture lessons from the Conservancy’s land management and restoration work and then share those lessons with other landowners – both private and public. In addition, Chris works to raise awareness about the importance of prairies and their conservation through his writing, photography, and presentations to various groups. Chris is also the author of "The Ecology and Management of Prairies in the Central United States", published by the University of Iowa Press. He lives in Aurora, Nebraska with his wife Kim and their children.
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7 Responses to Photo of the Week – May 2, 2013

  1. Robert Dana says:

    Most likely this plant depends on bumblebees for pollination. At the time it flowers only the overwintered queens are foraging, so the number of bees is limited. Perhaps bumblebee decline is aggravating this?

    • Chris Helzer says:

      Robert – I think you’re likely right about pollination being important. I tried to look up pollinators for this species, and didn’t find much, but I did see a note about a moth that pollinates it, so it might more than just bumblebees to help.

    • Patrick Swanson says:

      I have quite a bit of ground plum on my prairie, and this past weekend they were being pollinated by what I believe to be a member of the Mining Bees Family, Andrenidae. I have a very nice close-up picture of one with its proboscis in the flower. It takes a bigger bee to get to the nectar in this flower because it has to push its way in. I think I recall bigger solitary bumblebees foraging on these last year too, but I don’t have good photos.

      • Patrick Swanson says:

        In a previous post, I also mentioned that ground plum is a favorite target of voles, I have one ridge face where the voles cleared out most of the established ground plum this winter.

      • Patrick Swanson says:

        Photographed a bumblebee mimic hawk moth nectaring on ground plum today. Is that the moth you had read pollinates it?

  2. Green Knight says:

    also be aware that Astragalus and other pea and vetch-type plants suck up selenium and can be bad news for livestock. see “Death in the Marsh” by Tom Harris.

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