Petasites fragrans is native to the Mediterranean region. As its common name implies it produces attractive heads of fragrant, mauve flowers early in the New Year - a time when flowers of any kind are welcome.
With spring and the appearance of foliage however, the true character of the plant becomes evident - a large-leaved rampant perennial, spreading by means of underground stems by up to 1m (3ft) per year. It is very invasive, often forming large wayside colonies to the exclusion of all other vegetation.
Digging out is arduous. Spray mid-summer or later but before the leaves begin to die down, with a glyphosate-based weedkiller (such as Roundup or Tumbleweed), avoiding any nearby garden plants. If there is any re-growth the following spring, repeat-spray after mid-summer.