Registered by Jim Dishon of Michigan in 1996 as a hybrid of H. 'Galaxy' × H. 'Hadspen Heron'. It grows into a small size (10 inches high by 15 inches wide) mound with wavy, slightly corrugated foliage and pale lavender flowers in July.

According to The Hostapedia by Mark Zilis (2009), "The yellow margins of 'Mack the Knife' nicely contrast the green center. As noted, its appearance changes significantly with maturity."

The New Encyclopedia of Hostas by Diana Grenfell (2009) states: "Best suited to containers or rock gardens...The orange-yellow margin color fades toward the end of the season."