Hypericum perforatum
St. John's wort
Family HypericaceaeAlso called Common St. John's wort, Perforate St. John's wort
About
St. John's wort is a hairless perennial herb with black-dotted yellow flowers and leaves that look perforated. Long used in folk medicine, it has spread worldwide and is toxic to grazing animals.
Care at a glance
- Pet safety
- Toxic to dogs, cats and horses (hypericin); causes photosensitisation with skin inflammation.
- People
- Not recorded.
Field notes
Morphology
Erect stems 0.3–1 m tall grow from a woody root reaching 0.6–1.5 m deep, with creeping rhizomes. Stems are rusty-yellow to rosy with two edges. Translucent glands make the leaves appear pierced when held to light. One plant can produce thousands of seeds.
Distribution & habitat
Native across Europe except the far north, parts of North Africa, western and Central Asia and parts of China. Widely introduced in well-drained temperate habitats elsewhere.
Ecology
Reproduces by seed and vegetatively; summer rain helps it regrow after grazing or insect defoliation.
Cultivation notes
Poisonous to livestock such as cattle, sheep and horses: grazing causes skin reddening, swelling and necrosis, worst on pale skin, and sensitivity to sunlight. It is most toxic in spring and stays toxic in hay.
History & etymology
The type species of Hypericum, chosen for its wide distribution. Probably a hybrid of H. attenuatum and H. maculatum that arose in Siberia.
Habitat
- Altitude
- Not recorded
- Altitude class
- —
- Native to
- United Kingdom, France, Germany, Italy, Spain, Morocco, Algeria, Tunisia, Sudan, Saudi Arabia, Turkey, Afghanistan, China
Cultivation
- Difficulty
- Not recorded
Text adapted from Wikipedia, CC BY-SA 4.0.
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