It starts with a pink rose, astounding in its towering scale and vaguely threatening—each thorn on the stem is about the size of a butcher’s knife. This monumental steel flower seems as if it is finally at home in the surreal and weird context around the Neue Nationalgalerie in Berlin, where everything is a bit idiosyncratic. The iconic museum is where Isa Genzken is subject of a smartly styled exhibition to mark her 75th birthday called “75/75,” on view until the date of her birthday, November 27.