Although primarily associated with water courses, Indian Balsam (Impatiens glandulifera) is perfectly adapted for rapid colonisation of other types of ground, especially where there is soil disturbance. This is illustrated spectacularly at this clearfell site just south of Pontrhydyfen in the Afan Valley, presumably a larch plantation felled last winter. It will be interesting to see what this site looks like in subsequent years to see if the 'problem' persists.
distribution of Indian Balsam in West Glamorgan
NB. probably under-recorded in some areas