Hypericum ascyron, the great St. Johnswort or giant St. John's wort is a flowering plant in the family Hypericaceae.
This large species of Hypericum grows to be tall. It is perennial and its leaves are a deep green, elliptic, and grow up to long. Its flowers have five petals and it can have thirteen or more stamens.
Accepted infraspecifics include:
It is found Asia and North America, in the latter primarily in the American Midwest, as well as parts of New England and Quebec. It occurs in Russia, Mongolia, Korea, Taiwan, China, Vietnam, Canada, and the United States.