UK Biodiversity Action Plan.
Tower mustard is a biennial or sometimes short-lived perennial member of the cabbage family which generally favours light, nutrient-poor sandy soils often over chalk or limestone. Plants germinate in spring, spending at least one season in a vegetative state before flowering the following May-June. It can produce abundant seeds, which appear to remain viable for many years with plants often reappearing on old sites after long periods of absence. As a mobile and opportunistic species, it appears to be well matched to the traditional management cycle of extensive grazing with occasional arable cultivation.