Talk by Matthaei and Nichols Arboretum curator Mike Kost and ecological firm NatureWrite founder Jacqueline Courteau about the ecosystems oak trees support in Michigan. Attendees can take home a free oak seedling. 11 a.m.–noon. 1800 N. Dixboro Rd. Free; metered parking. Preregistration required at mbgna.umich.edu/events. (734) 647–7600.