Erect annual or biennial, herb, 0.4-2 m high. Fl. yellow, Oct to Dec or Jan to Feb. Roadsides, gardens, cultivated fields, disturbed sites.
Beard’s Provinces: Eremaean Province, South-West Province.
IBRA Regions: Avon Wheatbelt, Carnarvon, Esperance Plains, Jarrah Forest, Mallee, Murchison, Pilbara, Swan Coastal Plain, Warren.
IBRA Subregions: Avon Wheatbelt P1, Cape Range, Fitzgerald, Hamersley, Perth, Southern Jarrah Forest, Warren, Western Mallee, Western Murchison.
IMCRA Regions: Leeuwin-Naturaliste.
Local Government Areas (LGAs): Armadale, Ashburton, Bridgetown-Greenbushes, Bunbury, East Pilbara, Joondalup, Kondinin, Manjimup, Meekatharra, Ravensthorpe, South Perth, Three Springs.
Alternative Names. Wild Lettuce, Compass Plant.
General Biology. Growth form. Herb. Life form. Annual. Reproduction. Seed. Dispersal. Wind, water, soil movement. Toxicity. Possibly poisonous to mammals. Seedbank persistence. Short term, 1-3 years. Fire response. Can increase in abundance in suitable post-fire conditions.
Notes. Can be biennial or a winter or summer annual. Colonises a range of disturbed habitats including wetlands. Exudes a white milky sap when damaged. Most seedlings emerge in autumn, grow slowly and form a rosette over winter, and then develop stems in spring. Long, warm autumns favour emergence and rosette establishment, and often result in large populations the following year. Plants emerging in spring have a shorter rosette phase before flowering and are often smaller than plants emerging in autumn.Seeds have an attached pappus for wind-dispersal, have no primary dormancy and only form a short term soil seedbank. Seed production is proportional to plant height, with taller plants able to produce as many as 2,300 seeds. Research has shown it has broadened its ecological amplitude, enabling it to invade a range of vegetation types. Many populations in southern Australia have developed resistance to Group 2 herbicides.
Additional information. Origin. Eurasia, North Africa. History of use/introduction. Genetic resources (primary genetic relative of lettuce), ornamental, medicines.
Suggested method of management and control. Manually remove small and/or isolated infestations, ensuring entire plant is removed especially the taproot. Apply glyphosate at early growth or rosette stages in spring, summer or autumn or metsulfuron methyl 5 g/ha (based on a minimum of 50 L/ha of water) + surfactant. Plants are difficult to control with herbicides once the flowering stems have begun to elongate. 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/