Erysimum hieracifolium; The Hawkweed-leaved Treaclemustard is a common plant around the shores of lake Mývatn. Elsewhere on Iceland it is more rare. It is one of only a few yellow-colored mustard-family species on Iceland, readily recognized by its rather tall (about a ½m or more) erect appearance.
It is a member of the cabbage (= mustard) family) (Brassicaceae formerly known as Cruciferae). The Icelandic name of this species is Aronsvöndur.