This Common Comfrey was growing at the Children’s Botanical Garden yesterday (Kodomonoshokubutsuen). I’m sure you’ll notice the ant that’s exploring the plant.
Scientific name: Symphytum x uplandicum, Russian comfrey or Japanese name: (murasakika-)Hireharisou can be seen growing wild here. http://www.kconline.com/tg/uraniwa/Comfrey.html
Other info: Comfrey has been cultivated since about 400 BC as a healing herb. The word comfrey, derived from the Latin word for “grow together”, reflects the early uses of this plant. Greeks and Romans used comfrey to stop heavy bleeding, treat bronchial problems, and heal wounds and broken bones. Poultices were made for external wounds and tea was consumed for internal ailments.
Comfrey (Symphytum spp.) is native to Europe and Asia. Although comfrey has been used as a food crop, and as a forage crop, in the past 20 years scientific studies reported that comfrey may be carcinogenic, since it appeared to cause liver damage and cancerous tumors in rats. Comfrey-pepsin capsules, which are sold as a digestive aid in herbal and health-food stores in the USA, have been analyzed and found to contain pyrrolizidine alkaloids. These alkaloids cause liver damage in people and are a potential carcinogen. Huxtable et al. (1986) cited cases of hepatic veno-occlusive disease that were produced by using these capsules. These reports have temporarily restricted development of comfrey as a food crop.
Three plant species in the genus Symphytum are relevant to the crop known as comfrey. Wild or common comfrey, Symphytum officinale L., is native to England and extends throughout most of Europe into Central Asia and Western Siberia. Prickly or rough comfrey [S. asperum Lepechin (S. asperrimum Donn)], named for its bristly or hairy leaves, was brought to Britain from Russia about 1800. Quaker, Russian, or blue comfrey [S. × uplandicum Nyman (S. peregrinum Lebed.)] originated as a natural hybrid of S. officinale L. and S. asperum Lepechin. This hybrid was called Russian or Caucasian comfrey in reference to its country of origin. Cuttings of this hybrid were shipped to Canada in 1954 and it was named Quaker comfrey, after the religion of Henry Doubleday, the British researcher responsible for promoting comfrey as a food and forage. The majority of comfrey grown in the United States can be traced to this introduction