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Irish St. John's Wort

Hypericum canadense

Please keep in mind that it is illegal to uproot a plant without the landowner's consent and care should be taken at all times not to damage wild plants. Wild plants should never be picked for pleasure and some plants are protected by law.
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Plant Profile

Flowering Months:
Hypericaceae (St. John's Wort)
Life Cycle:
Maximum Size:
90 centimetres tall
Fields, grassland, heathland, meadows, moorland, riversides, waterside, wetland, woodland.

Yellow, 5 petals
Golden yellow star-shaped flowers, 5 to 7mm across. The petals each have a red line on their underside. The sepals are streaked red and do not have any black dots around the edges, as with some species of St. John's Wort.
The fruit is a capsule. In fruit from July to September.
An annual or short-lived perennial flower with red-tinted, square and slightly winged stems. The small leaves are slender and 3-veined, almost clasping their stems. The leaves appear in opposite pairs up their stems.
Other Names:
Canadian St John's Wort, Lesser Canadian St John's Wort, Lesser St John's Wort.
Frequency (UK):
Rarely seen  

Other Information


Hypericum canadense, also known as Canadian St. John's Wort, is a perennial herb that is native to North America. It has small, yellow flowers that bloom in the summer and is known for its unique red-purple spots on its leaves and stems. The plant is often found in wetland, meadows, and woodlands, and is valued for its attractive foliage and showy flowers. The plant is also known for its medicinal properties and has been used traditionally to treat a variety of ailments. It is considered a threatened species in some states.


Irish St. John's Wort, also known as Hypericum canadense, is a beautiful wildflower that is native to the eastern and central regions of North America, including parts of Canada and the United States. It is a member of the Hypericaceae family, which includes over 400 species of flowering plants.

The Irish St. John's Wort is a hardy perennial that typically grows to a height of around 2 to 3 feet, with a spread of about 2 feet. Its leaves are narrow, lance-shaped, and slightly pointed at the tip, and are a bright, glossy green color. The plant produces clusters of bright yellow flowers that are about 1 inch in diameter, each with five petals that are marked with small black dots. The flowers bloom in mid- to late summer and are pollinated by bees and other insects.

In addition to its striking appearance, the Irish St. John's Wort has a long history of use in traditional medicine. Its leaves and flowers contain a number of biologically active compounds, including hypericin and hyperforin, which are believed to have antidepressant and anti-inflammatory properties.

Some studies have suggested that extracts of St. John's Wort can be effective in treating mild to moderate depression. While more research is needed to fully understand the plant's medicinal properties, it is thought that these compounds work by increasing levels of certain neurotransmitters in the brain, such as serotonin, dopamine, and norepinephrine.

However, it's important to note that St. John's Wort can interact with certain medications, including antidepressants, birth control pills, and blood thinners, and should only be used under the guidance of a healthcare professional.

Irish St. John's Wort is a beautiful and fascinating plant with a rich history and many potential health benefits. Whether you're interested in its traditional medicinal uses or simply enjoy its bright, sunny flowers, this wildflower is a valuable addition to any garden or natural area.

Irish St. John's Wort is also known for its ability to grow in a variety of conditions. It is a hardy plant that can tolerate a range of soils, from dry and rocky to moist and loamy. It is also adaptable to a range of light conditions, from full sun to partial shade. This makes it a popular choice for gardeners and landscapers looking for a low-maintenance plant that can thrive in a range of environments.

In addition to its medicinal and ornamental uses, Irish St. John's Wort has also been used for a variety of other purposes throughout history. Native American tribes used the plant to treat a range of ailments, including wounds, fever, and digestive issues. European settlers later adopted many of these traditional uses and also used the plant to make a red dye for textiles.

Today, Irish St. John's Wort is sometimes used in natural or alternative medicine to treat a range of conditions, including depression, anxiety, and menopausal symptoms. However, as with any herbal remedy, it's important to talk to your doctor before using it to ensure it is safe for you and won't interact with any medications you are currently taking.

Irish St. John's Wort is a fascinating and valuable plant that has a long and varied history of use. Its bright, cheerful flowers and potential medicinal properties make it a great choice for anyone looking to add a splash of color to their garden or explore the world of herbal medicine.

Another interesting fact about Irish St. John's Wort is that it is named after St. John the Baptist, as the plant typically blooms around the time of the summer solstice, which is celebrated as St. John's Day in many Christian traditions. The plant has long been associated with various myths and legends surrounding this holiday and was thought to have magical properties.

Irish St. John's Wort is also an important source of food for a variety of insects and animals, including bees, butterflies, and moths. The plant's nectar and pollen are particularly attractive to these creatures and help support their populations. In addition, the plant's seeds are eaten by a variety of birds and small mammals.

Irish St. John's Wort is a fascinating and beautiful plant with a rich history and many potential uses. Whether you are interested in its medicinal properties, its ornamental value, or its ecological importance, this wildflower is sure to add value and interest to any garden or natural area.

While Irish St. John's Wort is native to North America, it has become naturalized in other parts of the world, including Europe and Australia. In some areas, it is considered an invasive species and is capable of outcompeting native plants. This is because the plant can form dense stands and has a prolific seed production, which allows it to rapidly spread and colonize new areas.

To control the spread of Irish St. John's Wort, it is important to monitor and manage populations of the plant. This may involve manual removal of individual plants, herbicide application, or a combination of both. In areas where the plant is not considered invasive, it can be a valuable addition to gardens and natural areas, providing a burst of color and supporting a range of pollinators.

In conclusion, Irish St. John's Wort is a fascinating plant with a rich history and many potential uses. From its traditional medicinal uses to its ornamental and ecological value, this wildflower has much to offer. However, it is important to be aware of its potential invasive tendencies and to manage populations accordingly. With proper care and management, Irish St. John's Wort can be a valuable addition to any landscape.

Distribution Map

Reproduced by kind permission of the BSBI.

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