Glaucium Mill.
Glaucium is a genus of ca. 23 species, all native in Eurasia (Mabberley 2008). Some species are cultivated for ornament (Cullen 1995c, Jäger & al. 2008) but Belgian records of Glaucium are, so far, never associated with horticulture. One species, Glaucium flavum Crantz, is a very rare and rather ephemeral native in coastal sands (Lambinon & Verloove 2012). It is sometimes recorded as an alien at inland locations, for instance on coalmine heaps in northwestern France (surroundings of Douai and Lens), relatively close to the Belgian frontiers.
1 Glabrous biennial or perennial. Petals pure yellow. Fruit glabrous (native) === G. flavum
Hirsute annual to perennial. Petals red to reddish-orange. Fruit hairy === 2
2 Petals ca. 30 mm. Flower buds ca. 20-30 mm long. Fruiting pedicels usually shorter than the subtending leaf. Annual === Glaucium corniculatum
Petals ca. 40-50 mm. Flower buds ca. 40-50 mm long. Fruiting pedicels elongating, usually longer than the subtending leaf. Perennial (or biennial) === G. grandiflorum
Literature:
Cullen J. (1967) Notes on the cultivated species of Glaucium and Dicranostigma (Papaveraceae). Baileya 15: 112-117.
Cullen J. (1995c) Glaucium. In: Cullen J. & al. (eds.), The European Garden Flora, vol. 4. Cambridge University Press, Cambridge: 115-116.
Fedde F. (1909b) Glaucium. In: Engler A. (ed.), Das Pflanzenreich 40. Engelmann, Leipzig: 221-238.
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. & Verloove F. (avec coll. Delvosalle L., Toussaint B., Geerinck D., Hoste I., Van Rossum F., Cornier B., Schumacker R., Vanderpoorten A. & Vannerom H.) (2012) Nouvelle Flore de la Belgique, du Grand-Duché de Luxembourg, du Nord de la France et des Régions voisines (Ptéridophytes et Spermatophytes). Sixième édition. Jardin botanique national de Belgique, Meise: CXXXIX + 1195 p.
Lawalrée A (1956b) Papaveraceae. In: Robyns W. (ed.), Flore Générale de Belgique, vol. 2, fasc. 2. Jardin Botanique de l’Etat, Bruxelles: 121-140.
Mabberley D.J. (2008) Mabberley’s plant-book (3th ed.). Cambridge University Press, Cambridge: XVIII + 1021 p.
Mory B. (1979a) Beiträge zur Kenntnis der Sippenstruktur der Gattung Glaucium Miller (Papaveraceae). Feddes Repert. 89: 499-594.
Mory B. (1979b) Ergebnisse einer Revision und Bestimmungschlüssel der Gattung Glaucium Miller (Papaveraceae). Gleditschia 7: 117-126.
Vent W. & Mory B. (1973) Beiträge zur Kenntnis der Sippenstruktur der Gattungen Glaucium Adans. und Dicranostigma Hooker f. et Thomson (Papaveraceae). Gleditschia 1: 33-41.