David Lowenstein, a PhD student from University of Illinois at Chicago, came to the lab at the Chicago Botanic Garden in December to use our x-ray machine for his research project. One of the species he using in his project is Echinacea purpurea.
Here's what David had to say about his project...
I am studying pollinators in Chicago and whether vegetable crops and wild flowers in various neighborhoods in Chicago receive sufficient pollination. To investigate this, I used a mobile garden consisting of eggplant, cucumber, and purple coneflower. Potted plants of these species were transported to Chicago neighborhoods and left outside for four and half hours. I observed bee visits to focal plants, sampled the neighborhood floral community, and allowed the plants to mature under pollinator exclusion netting in the UIC greenhouse to measure pollination services. I measured pollination of purple coneflower by X-raying the achenes at the Chicago Botanic Garden and recording the proportion of full achenes from each Echinacea flowerhead. I found a positive relation between bee abundance and human population density, and I will use data from X-rayed achenes to determine if pollination services are also related to population density or other land cover variables. To read more about this project that will continue in summer 2013, visit http://www.uic.edu/labs/minor/urban_pollination.html
Here are three of his x-ray images. If you click & enlarge these images, you will see that some achenes are empty and others have embryos.