Propagating false toadflax, Comandra umbellata

by Bernie Buchholz, Steward at Nachusa Grasslands

Bastard toad flax (Comandra umbellata) is a hemi-parasitic plant prominent in most of the remnant prairies at Nachusa Grasslands.  It is known to lightly parasitize most all of its neighbors.  Despite collecting thousands of seed over the past 20+ years, we have had virtually no germination in our plantings.  We tried every imaginable combination of scarifying and stratifying, various planting depths and addition of soil from existing stems.

We decided to try a genetic rescue.  We’d move pollen from one population more than a mile to the receiving population and hope the resulting seeds would germinate.  The biggest challenge is that Comandra flowers are a few millimeters across.

With high precision tweezers under a microscope my wife harvested tiny pollen bearing anthers.  She then delivered it to the stigma of the receiving flowers that had been previously bagged with nylon netting to prevent the regular pollinators – flies and small bees – from beating us to it.  I held each stem against the wind, and she dabbed the stigmas with pollen, carefully avoiding the five surrounding anthers.

We’ll soon collect the resulting fruits, plant them, and hope to see seedlings next Spring.  In the meantime, the Chicago Botanic Gardens is looking for mycorrhizae associations among the various populations and a separate genetic analysis to determine if the Comandra is all part of a mammoth clone or distinct populations that we might cross pollinate.

2005 crew at Nachusa who collected Commandra and Stipa.

Update: Our limited experiment of twenty-five transfers yielded only a single fruit. But Emma Leavens, the researcher from Chicago Botanic Gardens, subsequently determined that some of our Comandra populations are significantly different genetically from others. We will use that information next year to select the most promising matches for cross pollination when we try a larger sample.

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2 Responses to Propagating false toadflax, Comandra umbellata

  1. Ron Cress says:

    Thanks for the article and for showing us this tiny jewel at your AOTP tour.
    Ron

  2. James McGee says:

    At the GRN workshop this year, there was a field trip to the Military Ridge Heritage Prairie Area. I was amazed that they had success with sowing seed of species like Comandra umbellata and Viola pedatifida into former crop fields. I’ve worked with Viola pedatifida. I have only observed success when this violet was either transplanted from a rescue site or rich top soil had been relocated to create a native plant garden. I have never seen success with the Comandra, but I have not really tried either. I’ve collected seed and it was sown, but I have never observed nor been told that there was any success occurring from this effort. Although, I have not specifically checked. I do remember someone saying Citizens for Conservation had some success with this species. Also, Stephen Packard mentioned some success. Possibly, these successes were in pastured sites that still had the missing factor that this plant needed.

    https://woodsandprairie.blogspot.com/2019/06/rotten-bastard-toadflax-and-related.html

    It is more likely the problem is related to soil rather than seed viability. The prairie reconstruction site that had success in the Military Ridge Heritage Prairie Area had been previously choked with brush and trees which indicates the agriculture that occurred likely happened prior to the widespread adoption of synthetic fertilizers and pesticides.

    Certain clonal species, like Comandra umbellata, might be more easily established by moving divisions rather than collecting and sowing seed. This is how Chris Helzer says he has established sun sedge, Carex heliophilla, in his prairie restorations.

    https://prairieecologist.com/2011/02/08/when-is-a-prairie-restoration-reconstruction-project-successful/

    Since everyone says propagating this species is so difficult, I’m now going to have to try it.

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