Yes there is a white form - I have seen it in the wild in the Pyrenees. Many wildflowers have a white form (Gentianas, Phyteumas, Eritrichiums etc even Rhododendron ferrugineum, usually pink but 3 bushes of the purest white I saw in Nuria in the Spanish Eastern Pyrenees). It is just a lack of the usual colour pigment; a genetic 'problem' I guess.