Students in a University of Michigan biology project had been assigned to grow herbs, vegetables, annuals and perennials. Police are trying to find out whether someone's green thumb also was being used to grow pot.

The Ann Arbor News reports 11 small green plants believed to be marijuana were seized from a greenhouse in the school's Matthaei Botanical Gardens in Ann Arbor Township, near its main Ann Arbor campus.

Police say a school employee found the plants Monday on a table while monitoring the research project.

The plants were mixed in with the project, which involves about 80 students. Samples were sent to the Michigan State Police for testing.