The underground stems, or creeping stolons, are white and fleshy with swollen lumps (like the Michelin Man); more mature ones can have a bright yellow hue near the end. They are brittle so it can be difficult to remove them completely.

The green parts have been used in poultices to stem bleeding for centuries and scientific analysis has found antiseptic properties in extracts from the plant. One of the common names, Clown's Woundwort, was given to it by the herbalist Gerard after his talents were rejected by a workman who preferred to use Marsh Woundwort to heal a deep cut - it worked in a quarter of the time Gerard's remedy would have, but he regarded the man as a clown at first for rejecting his help.
The young shoots can be cooked like Asparagus, although they taste much better than they smell. The fleshy tubers are edible as well and are said to be nutritious - they look similar to Chinese Artichokes which are also in the Mint Family.

It does not withstand repeated close cutting and can be dug up, but some of the brittle tubers may missed, to throw up new shoots.
A systemic or translocated herbicide will work, eg. Gylphosate.

See also Common Hemp-nettle and Hedge Woundwort which have similar leaves and flowers.