Herbivores Beware: Biology Students Search for Cyanogenic Clovers on Campus

10/25/2023

The lawn in front of Masters Hall doubled as an outdoor science laboratory for students in upper school science teacher Kristina Gremski’s Biology: Evolution and Diversity class.

The search was for clover leaves and the mission back in the Morris Hall lab was to test for the presence of cyanide. Some clovers produce the poisonous chemical to protect themselves against herbivores, such as snails, slugs and voles. Students learned that the percentage of clovers that make cyanide varies with climate; part of their assignment was to determine the local percentage and if it correlates with the area’s climate, and to assess which environmental factors affect whether an area has more cyanogenic clovers versus non-cyanogenic clovers.

According to Dr. Gremski, this lab is based on a scientific study being conducted at the Washington University in St. Louis. The lab kit was initially created as a way of collecting more data from different regions of the country.

Out of the 16 clovers that the class tested, two tested positive for cyanide. “Since we were testing a natural population, I couldn’t tell the students what results to expect in advance,” Gremski said. “Part of what I like about this lab is that there is no ‘correct’ answer.”

Josie Leff ’25 found the lab fascinating. “My favorite part of the project was learning about the biological way that clover is able to produce cyanide without poisoning itself in the process,” she said. “I find it captivating how these highly developed and complex systems of defense have been designed, while not flawlessly, in a very effective and useful way.”

For Elizabeth Fletcher ’25, the main challenge was collecting the clover in the right way. “I really enjoyed learning about the different types of clovers in our area and the reasons why they do or do not produce cyanide,” she said.

The clover lab was part of the curriculum unit on natural selection in different species. The unit began with the evolution of finches in the Galapagos as they adapted to a drought. Next up: the evolution of lactose tolerance in humans. Editor’s note: If ice cream is involved, we’d be happy to participate in that lab.