Cotula L.
Cotula is, as currently understood, a genus of ca. 50 species, mostly confined to the southern hemisphere (especially South Africa) (Mabberley 2008). About 30-40 species formerly included in Cotula and chiefly originating in Australia and New-Zealand, are now accommodated in a separate genus, Leptinella Cass. Several species of the latter genus are cultivated as ornamentals (especially for carpeting; Cullen 2000, Jäger & al. 2008) and have been reported as naturalised escapes in lawns in the British Isles (see for instance Sell & Murrell 2006; more recently also in Germany, see Dickoré & al. 2009). They might have been overlooked in Belgium. The genus Cenia Comm. ex Juss., formerly represented as a wool alien in Belgium (Verloove 2006), is now included in Cotula.
1 Annual. Strigillose-villous throughout, especially when young (more or less glabrescent with age). Involucre 3-4 mm across. Leaf blade 2-3 pinnately lobed === Cotula australis
Perennial. Glabrous, +/- fleshy. Involucre 6-12 mm across. Leaf blade entire or irregularly toothed-lobed === C. coronopifolia
Additional aliens: Cotula anthemoides L. (Afr., As.; wool alien) and C. turbinata L. (syn.: Cenia turbinata (L.) Pers.) (S-Afr., wool alien).
Literature:
Bremer K. & Humphries C.J. (1993) Generic monograph of the Asteraceae-Anthemideae. Bull. Nat. Hist. Mus., London 23(2): 1-177.
Caro J. (1961) Las especies de Cotula (Compositae) del centro de la República Argentina. Kurtziana 1: 289-298.
Cullen J. (2000) Cotula & Leptinella. In: Cullen J. & al. (eds.), The European Garden Flora, vol. 6. Cambridge University Press, Cambridge: 619-620.
Dickoré W.B., Lewejohann K. & Urner R. (2009) Neufunde, Bestätigungen und Verluste in der Flora von Göttingen (Süd-Niedersachsen). Florist. Rundbriefe 42: 5-59.
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.
Sell P. & Murrell G. (2006) Flora of Great Britain and Ireland. Vol. 4 Campanulaceae – Asteraceae. Cambridge University Press, Cambridge: XXVIII + 624 p.
Verloove F. (2006) Catalogue of neophytes in Belgium (1800-2005). Scripta Botanica Belgica 39: 89 p.