St John's wort

• Perennial herb with woody stems 30–120cm tall in spring and summer.
• Stems have 2 opposite longitudinal ridges.
• Leaves are opposite, ovate to oblong, dotted with tiny, translucent, black oil glands.
• Flowers are bright yellow, 1–2cm in diameter with 5 petals.
• Fruits are sticky, 3-chambered capsules, containing densely pitted seeds about 1mm long.

• Can tolerate soils ranging from dry, rocky and shallow to deep and fertile.
• Found in grasslands, woodlands, pastures and forest plantations, and along riverbanks, roadsides and railway lines.

• Found in small populations near Stanthorpe and Toowoomba.

• Flowers late spring and summer.
• Produces 15,000–33,000 seeds annually.
• Seeds remain dormant for 4–6 months before germinating.
• Germinates from autumn to spring.

Economic

• Invades woodlands and pasture.
• Poisonous to livestock.

• Seeds and capsules are spread by water.
• Fruit can stick to machinery, tyres, shoes, clothing and animal fur.

• Find out how farmers can prevent weed spread.
• Find out how gardeners and outdoor enthusiasts can prevent weed spread.

Biological control

• Low level of biological control has been achieved in some areas in southern Australia with 2 Chrysolina beetles and the mite Aculus hyperici.
• Other insects are used in biological control programs in North America and New Zealand.

• St John's wort is not a prohibited or restricted invasive plant under the Biosecurity Act 2014. However, by law, everyone has a general biosecurity obligation (GBO) to take reasonable and practical steps to minimise the risks associated with invasive plants under their control.
• Local councils must have a biosecurity plan that covers invasive plants in their area. This plan may include actions to be taken on St John's wort. Some of these actions may be required under local laws. Contact your local council for more information.