Hibiscus L.
The generic limits of Hibiscus have considerably changed in recent times. As currently understood (see Mabberley 2008) it is a large genus of ca. 675 species, mostly native in warm-temperate, subtropical and tropical areas. It now includes, among others, Abelmoschus Med., Pavonia Cav.,… Many species are cultivated as ornamentals (see Bird 1997) but rather few are frequent in cultivation in Belgium.
Perennial shrub. Petals lilac or whitish with a darker spot at base, ca. 50 mm. Seeds with long white hairs. Leaves shallowly 3-lobed. Epicalyx segments 7-9 === Hibiscus syriacus
Annual herb. Petals pale yellow with a violet spot at base, ca. 20 mm. Seeds glabrous. Leaves (at least the upper) deeply palmately lobed. Epicalyx segments 10-13 === H. trionum
Literature:
Bates D.M. (1965) Notes on the cultivated Malvaceae: 1. Hibiscus. Baileya 13: 57-130.
Blanchard Jr. O.J. (2015) Hibiscus. In: Flora of North America Editorial Committee (eds.), Flora of North America North of Mexico, vol. 6. Oxford University Press, New York: 252-267. [available online at: http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=115438]
Bird S.A. (1997) Hibiscus. In: Cullen J. & al. (eds.), The European Garden Flora, vol. 5. Cambridge University Press, Cambridge: 224-227.
Hochreutiner B.P.G. (1900) Révision du genre Hibiscus. Annuaire Conserv. Jard. Bot. Genève 4: 23-191.
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.
Mabberley D.J. (2008) Mabberley’s plant-book (3th ed.). Cambridge University Press, Cambridge: XVIII + 1021 p.
Slavík B. (1992) Malvaceae. In: Hejný S. & Slavík B. (eds.), Kvĕtena České Republiky, vol. 3. Academia, Praha: 282-316.
Webb D.A. (1968) Hibiscus. In: Tutin T.G. & al. (eds.), Flora Europaea, volume 2. Cambridge University Press, Cambridge: 255-256.