David Hill wrote:

I seem to remember someone doubting my saying I had White Willow Herb
well here it is

Despite the frightening vigour of the pure species, I could never
produce quite enough of this. 3L pots, each with one or two flowering
stems would fly out of the nursery as soon as they were put out for
sale. It's a very lovely thing that doesn't seed itself about and is
well behaved for the most part. Occasionally it will run on very
sandy soils, but it rarely overpowers other plants and is easily
controlled.