Externship Final Day

I’m Rebecca Lerdau, a Junior at Carleton College. I’ve had a great time these past three weeks as a Carleton College extern at the Echinacea Project. I, and my classmate, Vo Dominguez were working with Jared Beck on the RemAg project looking at Andropogon gerardii’s (big bluestem) reproductive response to fire. 

Having a good time counting the X-Ray images

A big part of our work has been with creating new protocols for determining Andropogon seed set. Previously, the main method for finding Andropogon seed set has been dissecting every floret, but this isn’t realistic on a large scale. Around half of Andropogon’s florets aren’t able to produce seeds, but it can be difficult to distinguish between the two types of florets. We wanted to figure out a way to use inflorescence mass to find total amounts of florets that can produce seeds. We were able to count awns and look at the relationship between awn count and mass. We found a beautifully linear relationship between awn count and seed mass (our R^2 = 0.96!) which allowed us to make an equation to use mass to determine the amount of fruiting florets. We set out to try X-raying Andropogon to determine seed counts. This was also successful, and we created a classification system for counting seeds with X-ray images. 

We also got to try out our new seed set quantification system on some samples from the pilot RemAg experiment. We looked at the effects of burning on Andropogon seed set in 2022 from the pilot plots. While we were unable to find significant results with the data we were looking at, it was good to see that our protocols were working. The protocols are promising, and I look forward to seeing what happens with the larger RemAg project!


All in all, it’s been an awn-some experience working as an extern these past few weeks. I’ve learned so much. I’ve enjoyed getting to meet scientists and exploring CBG. We went on some lovely walks and got to see all sorts of cool plants. I had fun working with Andropogon and we even found a few seed predators! Thank you to Stuart, Jared, Wyatt, and Abby for this experience, and thank you to my fellow externs as well.