Invasive Plant

St. John’s wort

Hypericum perforatum
Warning icon


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.


Use the app

Observe and report to protect BC’s biodiversity

Report through this website

Use our form to tell us what you’re seeing and where.



Click or drag files to this area to upload. You can upload up to 3 files.
Please include photos of the suspected species to help potential identification by experts.
Please be specific and give us an address if possible.

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.

Play Clean Go


Learn about best practices

Go Further


Help protect BC from Invasive Species.