Hill’s Thistle Research at Sand Creek Prairie Plant Preserve

By Andie MacGowen and Alyssa Yuill

Sand Creek Prairie Plant Preserve is home to Hill’s thistle, and this may well be the last known extant population in southern Michigan. In order to help preserve this species of special concern, we are evaluating the genetic diversity of Cirsium hillii. We (Andie and Alyssa) are studying the 2012 and 2013 flowering seasons, respectively. We will be senior biology majors in the next academic year, and this project will serve as our senior thesis requirement at Hillsdale College. Our research is being directed by botany professor, Dr. Ranessa Cooper, and conservation genetics professor, Dr. Jeffrey Van Zant. Although there have been multiple studies conducted on the genetic diversity of Hill’s thistle, these studies will be the first conducted on a Michigan population. We are excited to be a part of understanding more about the genetics of the rare Hill’s thistle.

A controlled burn on the south side of the preserve.

A controlled burn on the south side of the preserve.

Sand Creek Prairie Preserve is located in Hillsdale County. The 12-acre land is bordered by Sand Creek and the land is covered with a large variety of ferns, shrubs, and plants. This habitat, oak barren/savanna, is unique for southern Michigan. Hill’s thistle prefers areas that are open and available to sunlight because that helps the seeds germinate. This past May, a controlled burn was done on the south side of the preserve that helped in clearing up leaf litter in the preserve. We were able to visit the site to observe the burn and continue to visit weekly to see the growth occurring in the Hill’s thistle population.

Andie suited up to help with the controlled burn.

Andie suited up to help with the controlled burn.

The Hill’s thistle is a short perennial (similar to Pitcher’s thistle) that generally flowers once before dying, around age two or three years. At death, the main taproot sends runners off to create more thistles. Many of the observed plants will hopefully contain the purple flowering head this season which begins in early June. In 2012, we collected data on how many plants were on either the north or south sides of the preserve. Once the thistles were blooming, we collected a leaf from about 120 plants in order to conduct the genetic analyses. We just completed this season’s population count, and the collection of leaf samples will take place soon.

Cirsium hillii rosette preparing to blossom.

Cirsium hillii rosette preparing to blossom.

Currently, we have analyzed several different sequences for about 40 of the collected leaves. We have been optimizing primers and evaluating sequence data over the last couple weeks. Due to the rarity of the habitat, Hill’s thistle is a species of special concern.  The dwindling number of available habitat is keeping Hill’s thistle populations low and possibly decreasing genetic diversity for the species. Our study hopes to find that the population is diverse and healthy, especially now that the preserve is being managed.

Ed. note: You can learn more and explore Sand Creek Prairie Plant Preserve on MNA’s 2013 Fall Adventure. Dr. Ranessa Cooper will join us on the Adventure to discuss research at Sand Creek Prairie Plant Preserve, and guests will have the opportunity to take a guided tour of the sanctuary (and several other MNA sanctuaries). For more information, visit the MNA website or call (866) 223-2231. 


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