Research at Chicago Botanic Garden: Cirsium pitcheri

Kay Havens, Chicago Botanic Garden

Chicago Botanic Garden’s Negaunee Institute for Plant Conservation and Science supports centers of excellence in conservation practice, science, and training, with an emphasis on understudied species with high conservation need. The research focuses primarily on preventing plant extinction, promoting plant diversity, and understanding plant interactions. Actions and outreach include advocacy, conservation synthesis, best practices for restoration and management, and partnerships with stewards and other stakeholders. Capacity-building efforts include graduate programs, internships, and citizen science.

Pitcher’s Thistle, Cirsium pitcheri T. & G. (Asteraceae), is a federally endangered species found on the dunes around Lake Michigan and Lake Huron. The Institute has worked with C. pitcheri on a number of fronts for 20+ years: seed banking, reintroduction, population trends, pest biocontrol, and understanding its role in the pollination network. It is a key resource for pollinators, with an extended blooming season peaking in July. Investigators recorded pollinators visiting the plant species in 40 plots over the course of a summer. They found that C. pitcheri had the most visits of any of the native dune plants observed and the greatest number of pollinator species. It was found to be a keystone species during a period of time when few other plant species were blooming in the sand dune community.