According to The Hostapedia by Mark Zilis (2009), "Carl Mack worked as a horticulturist at the University of Chicago during the 1940s and 1950s...in 1960, he printed a listing of 52 hostas...These hostas were listed under number without any known identification."

Carl operated Mackwoods Gardens in Lotus Woods, Spring Grove, Illinois prior to his death in 1965.