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.
Considered a holy herb, St. John's Wort was employed for a number of folkloric uses during the Middle Ages. It was once believed that the herb helped to protect people from curses, demons, and lightning.
In contrast to its many uses, some countries have identified St. John's Wort as an invasive species and noxious weed. Though useful to humans, it can be dangerous to livestock, sprouting up in pastures and causing photosensitivity to the grazing animals that feed upon it.