NPL, isolated from daffodil bulbs, has a specificity toward α-linked mannose, preferring polymannose structures containing (α-1,6) linkages. Binding to mannose polymers can occur via internal mannose residues and is not dependent on structural integrity of a non-reducing end sugar. NPL also binds some galactomannans, and differs in other binding characteristics from a related lectin, Galanthus nivalis lectin. Unlike Con A, LCA, or PSA, NPL does not bind glucose. Biotinylated Narcissus pseudonarcissus lectin has an appropriate number of biotins bound to provide the optimum staining characteristics for this lectin. This conjugate is supplied essentially free of unconjugated biotins and is preserved with sodium sodium azide.