Common spreading garden perennial well known for it's aromatic flowers, the oils of which have been used in the perfume industry. The leaves produce a green dye; the flowers and roots have a long tradition of medicinal use as a diuretic, heart tonic, and in restoring speech and memory although caution should be used as the plant is quite toxic. Native from China to Europe. Plants prefer a well drained rich loamy soil and moisture; divide every 3 to 4 years.