Comfrey (Symphytum officinal)

Comfrey in bloom. Photograph copyright — Patsy Collins

Symphytum officinale is a hardy perennial related to borage. It does best in a moist shady spot. As it’s likely to become invasive in ideal conditions, prone to mildew in less favourable spots, and grows wild in some areas, a few gardeners consider it a weed. That’s likely because they don’t know its many uses and have only seen the plainer varieties.