Seedling establishment and vegetative spread of Cirsium arvense (L.) Scop, in Victoria, Australia

Although large numbers or viable seeds of C. arvense arc formed in some districts of Victoria, the germination percentage declines rapidly in the first 2 years. No seedlings were established from seed artificially spread on pastures, although at two sites 6–8% and 12–6% of seed sown 0–5–1′0 cm deep into bare soil gave emerged seedlings, and 78% and 93% respectively of the seedlings survived. It is unlikely that C arvense is spreading rapidly by seed under the present management of permanent grassland. Patches of C. arvense were shown to have a pattern of development similar to plants such as Pteridium and Calluna that degenerate behind an advancing front. The annual rate of vegetative spread in pastures was about 150 cm and extremely variable (range 4–341 cm).