St John's-wort
Hypericum, family Hypericaceae
A genus of yellow-flowered plants known as St John's-wort or goatweed
Hypericum is a group of flowering plants found almost worldwide, except in deserts, tropical lowlands, and polar regions. Most have yellow flowers with dotted glands, and some are grown as ornamentals or used in traditional medicine, while others are considered invasive weeds.
- Hypericum includes over 490 species found almost worldwide
- Most species have yellow flowers with dotted glands
- Some are invasive and toxic to livestock
- Common St. John's-wort is used in traditional medicine
- Popular garden cultivars include 'Hidcote' and 'Rowallane'
What does St John's-wort look like?
Plants in the Hypericum genus can be herbs, shrubs, or rarely small trees. Most have opposite, stalkless leaves with dots or lines from oil and pigment glands. Their flowers are usually yellow, sometimes white or pink, with four or five petals and many stamens. Some petals or leaves may show red tinges or dots. The fruit is a capsule with small, brown seeds. Some species have showy blooms and are grown for gardens, while others are weedy.
Where does St John's-wort come from?
Hypericum grows wild in most regions of the world except deserts, tropical lowlands, and polar areas. The name comes from Greek, possibly referring to its use over shrines to ward off evil. Over 490 species are recognized, grouped into 36 sections. Fossil records show Hypericum has existed since at least the Eocene. Some species, like H. perforatum, have spread widely and become invasive in many temperate regions.
When and how St John's-wort blooms
Hypericum species grow in a range of habitats, from wetlands to dry slopes. Most bloom with yellow flowers, but some have white or pinkish petals. They are grown from seeds or cuttings, and many are cultivated as ornamentals for their bright flowers. Some species root from horizontal stems in wet ground, while others have taproots. Garden varieties and hybrids are available, including award-winning cultivars.
How St John's-wort is used
Common St. John's-wort (H. perforatum) is used in traditional medicine, especially in Europe, as a herbal remedy for mild to moderate depression. Several species are grown in gardens for their attractive flowers. However, some Hypericum species are invasive and toxic to livestock. The plant's glands produce chemicals that deter insects and herbivores. In some regions, insects have been introduced to control invasive Hypericum.
Kinds of St John's-wort
There are over 490 species in the genus, with notable ones including H. perforatum (common St. John's-wort), H. calycinum, and H. patulum. Cultivars like 'Hidcote' and 'Rowallane' are popular in gardens. Some species have white or pink flowers, while most are yellow. The genus is divided into 36 sections, each with its own features.
What St John's-wort means
The red pigment in some Hypericum species was linked to St. John the Baptist, giving rise to the name St. John's-wort. The plant has been used over shrines to ward off evil spirits. H. perforatum is recognized for its traditional medicinal use, but can be toxic to livestock and is considered a noxious weed in some areas. Some species are valued ornamentals.
Traditions that use it
Questions people ask about St John's-wort
Where does Hypericum come from?
Hypericum species are found nearly worldwide, except in deserts, tropical lowlands, and polar regions. They grow in a wide range of habitats, from wetlands to dry slopes.
What does St. John's-wort look like?
Most Hypericum species have yellow flowers with four or five petals and many stamens. The leaves are usually opposite and dotted with oil glands, and the plants can be herbs, shrubs, or rarely small trees.
What is Hypericum used for?
Common St. John's-wort (H. perforatum) is used in traditional medicine, mainly as a herbal remedy for mild to moderate depression. Some species are grown in gardens for their bright flowers, while others are considered weeds.
Is Hypericum toxic?
Some Hypericum species, especially H. perforatum, are toxic to livestock and can be invasive weeds in farmland and gardens. The plant's chemicals deter insects and animals from eating it.
Why is it called St. John's-wort?
The name comes from a link to St. John the Baptist. The red pigment in the plant was called 'Johannes-blut' (John's blood) in the 16th century, and the plant was used over shrines to ward off evil.
Good reading and sources
- Encyclopaedia BritannicaArticle
- Hypericum × moserianumRoyal Horticultural Society, Article
- Plants of the World OnlineRoyal Botanic Gardens, Kew, Plant database
- Where it has been recordedGBIF, Plant database
- Sightings and photos by naturalistsiNaturalist, Plant database
The facts on this page come from the Wikipedia article "Hypericum", written by its contributors and used under the CC BY-SA 4.0 licence, and from its Wikidata record (CC0). Phool rewrote the text in its own words, with AI assistance, and compares every page with the article to make sure no passage is copied. It may be reused under the same CC BY-SA 4.0 licence with a link back.
It may contain mistakes. It is not medical or foraging advice: many flowers are poisonous, and traditional uses are reported, not recommended. If something is wrong, tell us. Last refreshed 2026-10-03.
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