Cruciferous vegetables — the mustards, broccolis and cabbages of the world — share a distinct taste. But the same compounds that make them bitter also make them toxic at some levels. Biologists have mapped the crystal structure of a key protein that makes the metabolites responsible for the bitter taste in Brassicas. A new study is the first snapshot of how the protein evolved and came to churn out such diverse byproducts in this agriculturally significant group of plants.