Polatschek, A. 2013: Revision der Gattung Erysimum (Cruciferae): Teil 4. Nordafrika, Malta und Zypern. – Ann. Naturhist. Mus. Wien, B 115: 57-74Tutin, T.G., Burges, N.A., Chater, A.O., Edmondson, J.R., Heywood, V.H., Moore, D.M., Valentine, D.H., Walters, S.M. & Webb, D.A. 1993: Flora Europaea 1, ed. 2
but modified
1Annuals, without basal leaf-rosettes; siliques spreading, sometimes almost horizontal
1'Perennials, with basal leaf-rosettes; siliques erect or erecto-patent
2Petals 22-35 mm long; siliques 4-7 mm wide; leaves lanceolate to narrowly obovate
2'Petals 9.5-15 mm long; siliques 1.5 mm wide; leaves mostly spatulate with long petioles