Lamiaceae Herbaceous perennial. Native to Europe.
Growth habit resembles mint, with luxurious foliage for a moist location.
A few plants will eventually make a dense patch by way of creeping stolons. The dry leaf has numerous medical applications, including treatment of hyper-thyroidism and chronic cough. Black dyeplant, old English herb. Sow seed in flats and transplant to a moist situation. Tolerates sun or shade.