St. Johns Wort Herb Powder (Hypericum perforatum) 100 % Pure Powder, No Fillers 30 Count 375mg. each Also known as Hypericum perforatum, Perforated bush, Hypericum, and Klamath weed. Introduction Hepericum perforatum is one of many species known commonly as St John's Wort, and is the species most commonly associated with herbal medicine. It is native to Europe but has since been naturalized to other temperate climates around the world, with particular prominence in North America. The plant is a creeping perennial, producing star-shaped yellow flowers containing long, abundant stamens. St John's Wort is traditionally harvested near the beginning of the flowering cycle on St John's Day, which falls annually on June 24th. The flowers continue blooming throughout the summer and may be freely harvested throughout the season.