Status: Declared Noxious Weed (Regionally Controlled), Weed of National Significance.
Threat: High threat environmental weed.
Description: An erect, dense spiny branched shrub 2–4 metres tall.
Flowers: Bright yellow pea-like flowers 2–2.5cm long. Found in leaf axils and in clusters at the end of branches. Buds covered in stiff hairs that persist from flower to pod. Appear between July to October and March to May.
Leaves: Dark green, clover like with three leaflets and only present on young plants. Adult stage, leaves shed and replaced by narrow spines, 1–2.5cm long, stalkless and occurring in whorled clusters along the branches.
Stems: Green when young and turning brown and woody when mature. Ridged and hairy. Covered with spines and bearing short branches with spiny heads.
Fruits: Hairy oblong pod to 2cm long with up to six shiny hard black seeds.
Note: Introduced as a garden hedge. Prolific seeder and highly invasive. Forms dense stands excluding other vegetation. Seeds long lived in soil and regenerate readily after fire. A dense stand can produce six million seeds per hectare per year. May also provide critical habitat to small native birds and animals (e.g. bandicoots) if other native shrub species absent, so may require staged program of removal.
Control measures: Hand weeding, cut and paint with suitable herbicide, mowing/slashing, spot spraying, spot-burning.
Dispersal: Birds, water, animals, vegetative.