Purple Comfrey
Symphytum 'Moorland Heather' has dark dusky purple flowers from spring to early summer and then again later in the year if cut back. This variety doesn't spread and take over as some comfrey's do and the flowers are loved by bees.
Comfrey foliage is excellent in the compost heap where it improves the composting process and can also be used to make a plant food. An early use was in setting bones, the roots being ground to a paste and used in the way plaster of Paris is used today. The name comfrey comes from the Latin 'Conferre', meaning to bring together.