Plant Science: Areas of interest

Conservation Science

Regional Floristics

cirsium pitcherii (Pitcher's thistle)

Cirsium pitcherii (Pitcher's thistle)

Each spring, scientists from the Chicago Botanic Garden make their annual trip to Illinois Beach State Park to continue the work of saving a rare plant from extinction.

Pitcher's thistle (Cirsium pitcheri), native to the dunes along Lake Michigan, disappeared from the state around 1915. Two feet tall with a cream-colored head and fuzzy white leaves, it is now classified as threatened not only in Illinois but also throughout the United States.

To restore Pitcher's thistle, the Garden has been working since 1995 with The Morton Arboretum, which began the reintroduction project in 1991. Now each spring 200 plants that have been growing for a year are planted into the dunes. Director of Conservation Science Kayri Havens reports "good survival — 80 to 90 percent many years."

In addition, Garden scientists have conducted a genetic analysis of Pitcher's thistle populations in Indiana, Wisconsin and Michigan, along with DNA isolated from Illinois herbarium sheets. It showed that Illinois' pre-1915 plants are most similar to plants growing in Wisconsin.

"The project will be ongoing until the population is self-sustaining," Dr. Havens said. "Pitcher's thistle is important because it is part of Illinois' natural heritage."