Erect, clumped annual, herb, to 1 m high. Fl. yellow, Feb to Jul or Dec. Sandy soils. Alluvial flats & roadsides.
Beard’s Provinces: Eremaean Province, Northern Province, South-West Province.
IBRA Regions: Avon Wheatbelt, Coolgardie, Dampierland, Geraldton Sandplains, Murchison, Swan Coastal Plain.
IBRA Subregions: Avon Wheatbelt P2, Eastern Goldfield, Eastern Murchison, Geraldton Hills, Lesueur Sandplain, Perth, Pindanland.
IMCRA Regions: Abrolhos Islands, Central West Coast, Leeuwin-Naturaliste.
Local Government Areas (LGAs): Bayswater, Broome, Chittering, Coolgardie, Dandaragan, Gingin, Greater Geraldton, Irwin, Kalamunda, Leonora, Menzies, Moora, Northampton, Rockingham, Sandstone, Stirling, Wanneroo.
General Biology. Growth form. Herb. Life form. Annual or short lived perennial. Reproduction. Seed. Dispersal. Machinary, soil movements, roadworks, animals. Seedbank persistence. 2-3 years.
Notes. Disturbed sandy substrates are particularly vulnerable to invasion. Characteristics that make it a serious environmental weed include ability to invade native vegetation and displace native flora, high seed production, seed dormancy, ability to tolerate dry conditions and allelopathic effects. Can grow to 1.5m and forms dense stands. It is of particular concern on off shore Islands where it can cause substantial degradation to seabird habitat by creating a physical barrier to nesting birds, lowering nest density and shading out native plants. Toxic to stock.
Additional information. Origin. southeastern North America, parts of Central and South America. History of use/introduction. Introduced in early 20th century. Similar exotic species. Sunflower, Helianthus annua, Ursinia anthemoides (mountain marigold).
Suggested method of management and control. Hand remove isolated plants, including tap root, before seed set. Carefully dispose of plants as they are known to resprout roots. In degraded areas try 1% glyphosate + Pulse® 2 mL/L or in more intact bushland, Lontrel® 20 ml/10 L + wetting agent. Apply herbicide before seed set. Follow up control will be required on germinating seedlings for at least three years. Read the manufacturers' labels and material safety data sheets before using herbicides. For further information consult the Australian Pesticides and Veterinary Medicines Authority to determine the status of permits for your situation or state.
Legend: Y = Yes, regularly, O = Occasionally, U = Uncertain, referred by others but not confirmed.
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Western Australian Herbarium (1998–). FloraBase—the Western Australian Flora. Department of Biodiversity, Conservation and Attractions. https://florabase.dpaw.wa.gov.au/