Ageratina riparia (ASTERACEAE) Mistflower, Creeping Crofton Weed

Weeds to Whack

Perennial scrambling herb or shrub, sometimes to 1 m but usually smaller and scrambling (decumbent); native to Central and South America. A weed of damp areas such as gullies and creek banks. Leaves paired, narrow. Quickly invades frost free slopes. Leachate from the leaves has an allelopathic effect (restricting the establishment and growth of other species). Free seeder with mature plants producing from 10,000 to 100,000 seeds.
Photo: Robert Whyte

Flower Close-up

Flowers occur in fluffy white flower-heads. Similar to Crofton Weed Ageratina adenophora which usually has numerous upright stems and wider leaves. Declared in New South Wales and the Northern Territory, and is prohibited entry into Western Australia. Rated weed risk 4.6 out of 5 by the Queensland Herbarium.
Photo: Robert Whyte