Comfreys. For the most part these are invaluable but sometimes invasive groundcover 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.