Matthaei Botanical Gardens is part of The University of Michigan, on N. Dixboro Road, situated on 350-acres with a number of nature trails through mature woodlands, wetlands, several ponds, and a tall grass prairie. Founded in 1965 it has a rich collection of plants from all around the world including many Cacti and Euphorbia in the Arid House section of the Conservatory. Visit the official website.