Many believe the Volkamer lemon to be a hybrid between a lemon and the sour orange, though some say it's a hybrid with a mandarin lime (via Fresh Point). The inside flesh can look almost shrunken, the carpels narrow thanks to a thicker white pith. Nonetheless, the Volkamer lemon is fairly bitter and slightly acidic, with an overall pleasant flavor. It also has a rind rich in essential oils. Because of this, some people sensitive to acid will substitute "true" lemons with a Volkamer lemon.