Posted: 07/05/2013 at 19:26
This is an extract from the above article.
Seeds have a plume of hairs and are wind dispersed. It has been estimated that 20 to 50% of seeds may be carried 100 m by the wind and some could potentially travel over 100 km. Rosebay willowherb also spreads by the horizontal roots on which adventitious buds develop. The roots extend by up to 1 m per year and spread well beyond the aerial stems. Expansion is limited where soil fertility has declined.
Established colonies of rosebay willowherb may persist for long periods. On sand dunes in Holland, stands 35 years old have been identified. Fragments of root can produce adventitious buds within 3 weeks. Longer fragments are more successful at regeneration and sections shorter than 8 cm are unlikely to produce shoots. Even pieces of 20-year old roots can produce buds following soil disturbance.