Status: Declared Noxious Weed (Regionally Controlled).
Threat: High threat environmental and agricultural weed.
Description: An erect perennial herb up to one metre tall. New plants can be produced via creeping, shallow underground stems. Forms extensive infestations which exclude most other ground flora and prevents the establishment of over-storey plants.
Flowers and seeds: Flowers are bright yellow with five petals and form clusters at the end of the upper branches. Petals have small black dots along the margins. Seed capsule 5–10mm long, egg shaped and turns sticky brown when ripe with many seeds. Flowers from October to March.
Leaves and stems: Leaves hairless, green, but lighter in colour underneath. Distinct black-dotted glands along the leaf surface. Leaves occur in opposite pairs along the stem and are oval to oblong in shape. Numerous small oil glands are apparent when the leaf is held up to the light. Stem is green or reddish-green and sometimes features two ridges. Branched towards the top.
Note: May cause photosensitivity in stock.
Similar indigenous species: Could be confused with native Hypericum species, such as Matted St. John’s Wort (H. japonicum) or Small St. John’s Wort (H. gramineum). Both native Hypericum species are slender herbs up to 30cm high with four-sided stems, usually solitary flowers, gold to orange flowers and small rounded petals.
Control measures: Hand weeding, spot spraying.
Dispersal: Animals, machinery, water, vegetative, wind.