common Saint-John’s-wort

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Saint-John's-wort

common Saint-John’s-wort

plant

Also known as: perforated Saint-John’s-wort

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July 23, 2026

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Saint-John's-wort — Saint-John's-wort Hypericum elatum, a species of Saint-John's-wort.

Saint-John's-wort refers to plants in the genus Hypericum, which includes nearly 500 species of herbs and shrubs native to temperate and tropical regions. These plants are characterized by simple, gland-dotted leaves and typically five-petalled yellow flowers with numerous stamens. The common name originates from the fact that many European species bloom around June 24, the feast day of St. John the Baptist, with "wort" being an Old English term for herb or plant.1

Common Saint-John's-wort (Hypericum perforatum) is particularly significant in herbalism and is used in some traditional medicine for treating depression, though clinical evidence for its efficacy is limited. This species can be toxic to grazing animals, causing photosensitization and other adverse effects. It has also become an invasive species in several parts of the world, including Australia and the Americas. Other species, like creeping Saint-John's-wort and goldencup Saint-John's-wort, are cultivated for their ornamental flowers.1

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weed
Biological control
…the western United States, where Saint-John’s-wort, or Klamath weed (Hypericum perforatum), was subjected to depredation by three insect species, beginning in California in 1945. The release of two insects of the genus Chrysolina and one of the genus Agrilus continued for a number of years, and the effort was carried…
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…the western United States, where Saint-John’s-wort, or Klamath weed (Hypericum perforatum), was subjected to depredation by three insect species, beginning in California in 1945. The release of two insects of the genus Chrysolina and one of the genus Agrilus continued for a number of years, and the effort was carried…
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nutritional disease
Food-drug interactions
Also, the herbal supplement St. John’s wort can alter the metabolism of drugs such as protease inhibitors, anticlotting drugs, and antidepressants, and it can reduce the effectiveness of oral contraceptives.
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Also, the herbal supplement St. John’s wort can alter the metabolism of drugs such as protease inhibitors, anticlotting drugs, and antidepressants, and it can reduce the effectiveness of oral contraceptives.
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Malpighiales
The Clusiaceae group
Bonnetiaceae, Podostemaceae, and Hypericaceae have many anatomical features in common. Their inflorescence is cymose; their petals overlap each other regularly in bud; and their flowers lack a nectary. Their capsular fruit opens down the radii of the partitions, and their seeds and embryo are distinctive. Within this group,…
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Bonnetiaceae, Podostemaceae, and Hypericaceae have many anatomical features in common. Their inflorescence is cymose; their petals overlap each other regularly in bud; and their flowers lack a nectary. Their capsular fruit opens down the radii of the partitions, and their seeds and embryo are distinctive. Within this group,…
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phytotherapy
Standardization
For example, St. John’s wort (H. perforatum) is used in both phytotherapy and herbalism. In the former, the preparations often are industrially produced extracts from the leaves and plant tops that have been standardized according to hypericin and hyperforin content (or sometimes one or the other). These…
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For example, St. John’s wort (H. perforatum) is used in both phytotherapy and herbalism. In the former, the preparations often are industrially produced extracts from the leaves and plant tops that have been standardized according to hypericin and hyperforin content (or sometimes one or the other). These…
Read More

fairy
Several herbs, especially St.-John’s-wort and yarrow, are potent against fairies, and hawthorn trees, foxglove, and groundsel are so dear to them that abuse of these plants may bring retribution.
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Several herbs, especially St.-John’s-wort and yarrow, are potent against fairies, and hawthorn trees, foxglove, and groundsel are so dear to them that abuse of these plants may bring retribution.
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Saint-John’s-wort
…flowers, and at least one, common Saint-John’s-wort (Hypericum perforatum), is important in herbalism. The common name stems from the fact that various European species flower around June 24, which is the feast day of St. John the Baptist; “wort” derives from an Old English word for herb or plant.
Read More
…flowers, and at least one, common Saint-John’s-wort (Hypericum perforatum), is important in herbalism. The common name stems from the fact that various European species flower around June 24, which is the feast day of St. John the Baptist; “wort” derives from an Old English word for herb or plant.
Read More