Where you have room these can be dramatic and handsome plants, good for covering the soil, binding banks around large ponds etc. These are in the Asteraceae family, but the flowers lack the 'ray-florets', so less showy than many others in the same family, but still attractive in their own right, with the 'disc-florets' often coloured, in good numbers and appearing before the leaves have fully emerged. Out early in the year, so a good nectar source for insects. Careful siting required as these plants are spreading to invasive.
The numerous small flowers that make up the flowerheads of all butterburs are outstandingly attractive to all manner of pollinating insects especially honeybees, bumblebees and hoverflies, especially important given their early spring flowering period. The large leaves that follow the flowers provide shelter to invertebrates and amphibians, although they can dominate areas completely, to the detriment of native wildlife. P. japonicus especially seems to be spreading in the British countryside along watercourses, although as male-only clones, it cannot be spreading by seed - deliberate planting into the wild is considered to be main factor. Needless to say, this should never be contemplated...