Production, Dispersal and Predation of Seeds in the Biennial Cirsium Vulgare

(1) Seed production of flowering plants of Cirsium vulgare without damage to the flowering stem varied strongly between years in the sand-dunes at Meijendel. The percentage of plants that were noticeably damaged by herbivores also varied between years, and caused a reduction of the seed production by 80% in 1982 and 15% in 1984. (2) Mean seed loss by predation in the flowerheads was 3% in 1982 and 17% in 1984. (3) Seed dispersal was limited: 50% of the seeds were dispersed within 1 m of the parent plant and only 11 % of the seeds were dispersed outside the local population. (4) On average 60% of the seeds were consumed by mice and voles after dispersal. Only 1% of the seeds produced were still viable after one year.