WEEDS IN AGRICULTURAL CROPS .2. LIFE-FORMS AND OCCURRENCE IN A EUROPEAN PERSPECTIVE

A grouping of weeds regarding their life-forms with special emphasis o n their different occurrence in agricultural crops under Swedish condi tions is tested for Europe as a whole. Data from a European weed surve y made available by a group working in biological control are used. Th e occurrence of weeds of different life-forms shows, in principle, the same pattern for Europe as a whole as for Sweden and can be described satisfactorily by the grouping used in Sweden. As in this country, no typically biennial species are found among the more important weeds. Stationary and stoloniferous perennials, sensitive to soil cultivation , are of minor importance, particularly in annual crops sown or plante d after soil cultivation. Annuals predominantly occur in these crops. In orchards and vineyards with their, at least partly, mechanically or chemically disturbed area they are more apparent than in Swedish pere nnial leys. Among the perennials, only those with strong creeping rhiz omes or creeping roots are important weeds in annual crops, and some o f them are even more important in orchards and vineyards than they are in Swedish leys.