Knautia is a genus of ca. 60 species, native in Eurasia and the Mediterranean area. Two species are native in Belgium: Knautia arvensis (L.) Coulter (more or less widespread) and K. dipsacifolia Kreutzer (very rare and local). Rather few species are cultivated as ornamentals in Europe (Matthews 2000, Jäger & al. 2008) and some are weeds of arable land.
Wild flower seed mixtures often comprise very vigorous plants of Knautia arvensis (see Frank & John 2007). Such plants have also been recorded in Belgium, for instance on a coalmine heap in Souvret (terril Puits Périer) near Charleroi (since several years and confirmed in 2010). The exact identity of these plants is uncertain and possibly requires further research.
1. Annual. Calyx with 12-24 very inconspicuous teeth (largely obscured by hairs) === Knautia integrifolia
1. Perennial to biennial. Calyx with 8 teeth, awns conspicuous === 2
2. Corolla dark red. Basal leaves usually absent at flowering === K. macedonica
2. Corolla bluish-violet to lilac. Basal leaves present at flowering (native) === Knautia arvensis and K. dipsacifolia
Literature
Bobrov E.G. (1972) Dipsacaceae. In: Shishkin B.K. (ed.), Flora of the U.S.S.R., vol. XXIV. Academic Scienc. U.S.S.R.: 9-66.
Ehrendorfer F. (1976) Knautia. In: Tutin T.G. & al. (eds.), Flora Europaea, vol. 4. Cambridge University Press, Cambridge: 60-67.
Frank D. & John H. (2007) Bunte Blumenwiesen – Erhöhung der Biodiversität oder Verstoss gegen Naturschutzrecht? Mitt. florist. Kart. Sachsen-Anhalt 12: 31-45.
Jäger E.J., Ebel F., Hanelt P. & Müller G. (eds.) (2008) Rothmaler Band 5. Exkursionsflora von Deutschland. Krautige Zier- und Nutzpflanzen. Springer Verlag, Berlin: 880 p.
Lambinon J., Delvosalle L., Duvigneaud J. (avec coll. Geerinck D., Lebeau J., Schumacker R. & Vannerom H. (2004) Nouvelle Flore de la Belgique, du Grand-Duché de Luxembourg, du Nord de la France et des Régions voisines (Ptéridophytes et Spermatophytes). Cinquième édition. Jardin botanique national de Belgique, Meise: CXXX + 1167 p.
Matthews V.A. (2000) Knautia. In: Cullen J. & al. (eds.), The European Garden Flora, vol. 6. Cambridge University Press, Cambridge: 458-459.
Szabó Z. (1911) A Knautia génusz monográphiája. Math. Term. Közl. 31: 1-436.