Welsh Groundsel is endemic to North Wales but was previously known from Scotland where it is now extinct. Its habitat is entirely artificial and comprises urban sites where there is suitable bare ground for seedling establishment. Such areas comprise waste ground, stone walls and the edges of roads and pavements. The Welsh Groundsel is one of our most threatened plants. This recently evolved species formed from a hybrid between Oxford ragwort Senecio squalidus and Common Groundsel Senecio vulgaris. In 1983 the Welsh population numbered 2226 individuals, in 2004 the population numbered 349 individuals, the most recent detailed survey undertaken in 2011 found just 168 plants. These patterns of decline mirror that of the Scottish population that declined rapidly until it became extinct in 1993. Lack of open ground, herbicide applications to roadside verges, and the winter salting of roads are the most likely reasons for its decline. As a wild plant Welsh Groundsel appears to be heading towards extinction and as such plants held in cultivation by us and other botanical institutions will become particularly important.