Type of plant
About this weed
This plant is either an annual or short-lived perennial and is widely distributed across the near coastal sandy sites and disturbed bushland areas from Karratha south to Eucla. Originally from Africa and southern Europe and temperate Asia including India, it was probably introduced as an ornamental or carried as a seed contaminant. Onion Weed is a Declared Noxious Weed in Victoria.
Onion Weed produces a large clump of hollow, cylindrical leaves up to 40 cm’s long, hence the name as the leaves are ‘onion’ like. The stalks have many branches holding white flowers with a distinctive brown line at the center of the petal. Flowers are produced in winter and spring and are held high on a many branched stalk. Reproduction is by seed which is dispersed by the wind, machinery, water and clothing. Seeds germinate at any time of year however the main flush occurs during late summer and autumn. After spring, the flowering portion dies away. Leaves remain over summer and new leaves are produced from the base of the plant the following autumn. It has been reported to cause dermatitis. The seedbank persists for several years. Once established it is frost and drought–hardy.
Impact on Bushland
If left it will spread through coastal vegetation and impact on ecological processes and plant communities. It is capable of growing and spreading rapidly.
This weed is principally a weed of alkaline sandy or gravelly well-drained soils in winter rainfall areas. It is often found on sandy coastal sites and disturbed areas usually on sand, clay or calcareous soils. Frequently it is found in sites with low nutrient levels and may depend on its mycorrhizal associates for nutrients and growth.
Priority for removal
Unknown: but will impact on ecological processes and plant communities.
Hand pull small infestations at any time of the year.
Apply metsulfuron-methyl at 0.1 g /10 L + 100 ml spray oil when flowering. Read the manufacturers’ labels and material safety data sheets before using herbicides. Optimal months for spraying are July to October.
June, July, August, September, October
Hussey, B.M.J., Keighery, G.J., Dodd, J., Lloyd, S.G. and Cousens, R.D. (2007) Western weeds. A guide to the weeds of Western Australia, Second Edition, The Weeds Society of Western Australia, Victoria Park, Western Australia.