Unlike Ulex europaeus and Lotus tetragonolobus lectins which prefer (α -1,2) linked fucose residues, Aleuria aurantia lectin binds preferentially to fucose linked (α -1,6) to N-acetylglucosamine or to fucose linked (α -1,3) to N-acetyllactosamine related structures. AAL also reversibly binds fucose attached to nucleic acids. Fluorescein labeled Aleuria aurantia lectin has an appropriate number of fluorochromes bound to provide the optimum staining characteristics for this lectin. This conjugate is supplied essentially free of unconjugated fluorochromes. The excitation maximum is at 495 nm and the emission maximum is at 515 nm.