Invasive Plant

St. John’s wort

Hypericum perforatum
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Warning

St. John’s-wort contains a poison that can cause light-coloured farm animals that eat it to have skin burns or blisters when exposed to sunlight.

About This Species

This plant is a perennial that grows in dense patches which can crowd out natural plants and reduce the grasses that animals feed on. St. John’s-Wort is found in most of southern BC. St. John’s-Wort spreads by lateral roots and can produce up to 100,000 seeds per plant.

How to Identify

St. John’s-Wort grows from 0.3 – 1 m in height and has dark green leaves which show tiny transparent dots when held up to the light. Flowers are bright yellow, with 5 petals each, and grow in clusters at the top of branches. It turns a rusty red colour after finishing flowering late in the summer and autumn.

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Take Action

Hand pulling or digging St. John’s-Wort before the flowers go to seed can reduce the spread of this plant. Remove as much of the root system as possible to help prevent regrowth.

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