Inula helenium
 
Also called horse-heal and elfdock.
 
Hardy perennial in the aster family. Easy to grow and produces yellow flowers on tall long spires. Can get 6 feet tall when flowering, otherwise the foliage does not exceed 2-3 feet.
 
Produces a large root that increases in size each year with many medicinal uses. Often used to treat respiratory issues and improve digestion. 
 
Sold as a bare root crown piece with one shoot or as seeds with a minimum of 25 per pack.