Erect, robust, spiny annual or biennial, herb, to 1.8 m high. Fl. yellow, Oct to Dec or Jan. White to grey sand, brown clayey loam, black sandy loam, black clayey peat. Dunes, valleys, seasonally wet areas, watercourses, lakes and wetlands, disturbed sites.
Beard’s Provinces: Eremaean Province, South-West Province.
IBRA Regions: Avon Wheatbelt, Carnarvon, Coolgardie, Esperance Plains, Geraldton Sandplains, Hampton, Jarrah Forest, Mallee, Swan Coastal Plain, Warren.
IBRA Subregions: Avon Wheatbelt P1, Avon Wheatbelt P2, Cape Range, Dandaragan Plateau, Eastern Mallee, Fitzgerald, Hampton, Lesueur Sandplain, Mardabilla, Northern Jarrah Forest, Perth, Recherche, Southern Cross, Southern Jarrah Forest, Warren, Western Mallee.
IMCRA Regions: Leeuwin-Naturaliste.
Local Government Areas (LGAs): Albany, Armadale, Augusta Margaret River, Bayswater, Bridgetown-Greenbushes, Busselton, Carnarvon, Chittering, Cockburn, Collie, Cranbrook, Cuballing, Dandaragan, Denmark, Dundas, Esperance, Gingin, Kent, Lake Grace, Manjimup, Mount Marshall, Murray, Nannup, Narembeen, Northam, Plantagenet, Ravensthorpe, Rockingham, Serpentine-Jarrahdale, Swan, Toodyay, Victoria Plains, Wagin, Waroona, West Arthur, Williams, Wyalkatchem, Yilgarn, York.
Alternative Names. Rough Sowthistle, Spiny Sow Thistle.
General Biology. Growth form. Herb. Life form. Annual. Reproduction. Seed. Dispersal. Wind, occasionally water. Seedbank persistence. 1-2 years.
Notes. May be biennial. Most seed germination occurs in autumn or spring but can occur thoughout the year. Seeds are equipped with a small pappas for wind dispersal over large distances. Cut stems exude a milky sap. Sowthistle species including Sonchus asper have been the target of biological control programs overseas. In Australia preliminary surveys for biological control agents found a potential rust fungus and eriophyid mite. Biotypes in Canada have been found to be resistant to metsulfuron methyl. Can hybridise with Sonchus oleraceus.
Additional information. Origin. Europe, tropical and temperate Asia, Africa, however its exact native range is obscure. Similar exotic species. Sonchus oleraceus. Similar native species. S. hydrophilus.
Suggested method of management and control. Slashing is often ineffective as plants can continue producing flowers and seed. Remove small and/or isolated populations manually prior to seed set. Otherwise apply Lontrel® at 10 ml/10 L + wetting agent preferably when plants are at the rosette stage. 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/