The Verdigris Marsh was a location on Cóis Dara just west of Prince Manor. It was home to many native flowering plants, and it was the place Eileen Valora Prince started teaching her son, Severus Donovan Snape, about the wild plants there, such as the dichromena spurium, and their medicinal uses in healing potions. One such plant Severus remembered was red valerian, when mixed with ground willowbark it eased headaches. The Verdigris marsh, also the location of the Urnthatch Fen, was fed by the Lagan canal.