An Etymological Dictionary of the German Language/Raden
Raden, m., ‘cockle-weed,’ from MidHG. râde, usually râte, ratte, râten, ratten, m., ‘a weed among corn,’ OHG. râto, ratto, m.; so too OLG. râda, f., ‘weed.’ In Franc. and Henneberg râdme occurs, in Swiss and Suab. ratte. Perhaps the numerous forms of this simply MidEurop. Teut. word point to a primit. G. râþwo- (prim. form rêtwo-). cognate terms in the non-Teut. languages have not yet been discovered.