Comfreys. For the most part these are invaluable but sometimes invasive ground cover for any shady position and thrive on moister clay soils. That said others are much more well behaved, choice plants. The variegated forms provide bright feature plants in darker areas. S. ibericum 'All Gold' is as bright as a daffodil in early spring. Symphytum are adaptable, growing in sun or shade although ideally the soil should not dry out to much. We routinely shear the foliage off to ground level when flowering has finished just to keep the more vigorous varieties in check. They soon refurnish into much more manageable plants.
The flowers of all comfrey species and varieties are a magnet for visiting pollinators, from honeybees and bumblebees, to hairy-footed flower-bees and bee-flies , the latter especially early in the season, although flowering will in fact continue for many months, The densely creeping growth provides important shelter for beneficial ground insect predators and amphibians; their tendency to dominate means that all steps should be taken to limit spread from gardens, but for many forms sg S. x uplandicum that particular horse bolted in the mid-19th century.