Symphytum – Comfrey –
There are 25-35 rapidly growing, coarse,, sometime invasive, bristly or hairy, rhizomatous perennial in this genus. They are found naturally occurring in damp, often shady habitats, including woodland, scrub, wasteland, stream sides, and roadside, in Europe, Northern Africa, and Western Asia. Some are used medicinally or for liquid plant food or green manure. They have fleshy roots and long stalked, oblong to ovate-lance-shaped or elliptic, wrinkled prominently veined, mostly basal leaves. Erect, usually branched stems often become decumbent, they bear smaller, more or less stalkless leaves and terminal cymes of pendent, tubular flowers consisting of a tube terminating in 5 triangular lobes. Flowers can be blue, purple, pink, yellowish white, or white. Excellent groundcover plants for a shady border or woodland garden, but they can be rampant. S. officinale is used in healing creams, teas, and other herbal medicines, but is legally restricted in certain countries. Roots and leaves may cause severe discomfort if ingested, contact with foliage may irritate skin.
Easily grown in moist, moderately fertile soil, with added manure, in full sun or partial shade. Site carefully, since all but the variegated cultivars may be very invasive, even small pieces of detached root will form new plants. To keep the foliage attractive, remove flower stems of variegated cultivars as they form.
S. x uplandicum – Russian Comfrey -This erect, bristly perennial is a cross between S. asperum and S. officinale and grows 6′ feet tall and at least 4′ feet wide. It produces hairy, oblong, mid green basal leaves, to 14″ long. From late spring to late summer, many branched stems bear cymes of pinkish blue buds, opening to blue purple flowers, to 3/4″ long.