North American Fruit Explorers mailing list at ibiblio

["Ernest Plutko" <ernestplutko@wiktel.com>]

There are small opuntias that grow in southern, western Michigan on
sandy areas near Lake Michigan. When I lived there I saw several that
a friend had collected and was growing in pots.  Opuntia doesn't
necessarily mean large prickly pear cactus.  I was exploring in South
Dakota and saw many small opuntias growing on a rocky hillside. 
Mentioned it to a native who lived in the area.  He swore that was
impossible.  Finally had to take him to the site to prove it.