THE IMPORTANCE OF SEEDS AND SEXUAL REPRODUCTION IN THE POPULATION BIOLOGY OF CIRSIUM-ARVENSE - A LITERATURE-REVIEW

In this review the available information on the sexual reproduction of Cirsium arvense L. (Scop.) is summarized and discussed in an ecologic al context. Certain aspects of its sexual reproduction system have giv en C. arvense a reputation for low efficiency: the dioecious mating sy stem and dependence on insects for pollination and non-adaptive featur es for wind dispersal. The seeds are moderately persistent in soil and , for a temperate weed, have a high temperature requirement for germin ation. It is concluded that the contribution that sexual reproduction makes to the survival and spread of this species has been underestimat ed, partly owing to an inadequate number of studies. Seedling recruitm ent via sexual reproduction may be an important mechanism for initiati ng continued genetic diversity at intra- and inter-population levels.