Malva pusilla Smith (syn.: M. borealis Wallr., M. rotundifolia L.) (N-, C- and E-Eur., W-As.) – A regular but usually ephemeral alien, known in Belgium at least since 1872. Formerly chiefly introduced with wool in the Vesdre valley. In more recent times usually associated with grain importation. Malva pusilla is found in similar habitats as M. parviflora. Recent records are chiefly from port-areas. It is probably increasing in recent times but might be confused with M. parviflora and other small-flowered species. In some locations sometimes persistent for several years.
Selected literature:
Ludwig W.(1990) Malva pusilla SM. als "Dorfpflanze" in Hessen, mit Anhang uber die adventive Malva parviflora L. Hess. Flor. Briefe 39(1): 1-10.
Makowski R.M.D. & Morrison I.N. (1989) The biology of Canadian weeds. 91. Malva pusilla Sm. (= M. rotundifolia L.). Canad. J. Pl. Sci. 69(3): 861-879.
Svensson R. & Wigren M. (1993) Vit kattost: historia och biologi i Sverige. Svensk Bot. Tidskr. 87(2): 81-92.