What is the significance of Constance's red tongue?

Red is color traditionally associated with these symbolic meanings:  passion, aggression, desire, love.  The association of these traits with Constance are very important.  Although she begins the plays as a passive woman, unlucky in love, her true nature proves to be self-assured and passionate woman who goes after what she wants.  Her red tongue, along with her red cap, are hints to her inner nature.