High concentrations of glucoraphanin, and its isothiocyanate derivative, sulforaphane, can be obtained from whole plants, plant parts or extracts obtained from a new and distinct, highly inbred, and highly self-compatible Brassica oleracea L. (Italica group) broccoli variety designated `Hopkins`. The new broccoli variety `Hopkins` produces consistent yields of seed with a consistent high glucoraphanin concentration of greater than 60 .mu.mole of glucoraphanin per gram of seed (with an average range of 68-85 .mu.mole of glucoraphanin per gram of seed) when analyzed by Hydrophilic Interaction Liquid Chromatography (HILIC) and greater than 80 .mu.mol of glucoraphanin per gram of seed (with an average range of 85-105 .mu.mole of glucoraphanin per gram of seed) when analyzed by C.sub.18 Reverse-Phase HPLC.