Auld, B.A. & Medd, R.W. (1987) Weeds An Illustrated Botanical Guide to the Weeds of Australia. Inkata Press, Melbourne & Sydney.
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Tumbleweed (Amaranthus albus) is a low growing erect to decumbent (with branches growing horizontally but turned up to erect at the ends), annual herb, to about 80 cm high and can be over a metre wide. The stems are rigid, branching, whitish, glabrous (hairless) or glabrescent (initial with hairs soon becoming hairless). Occasionally, plants are tinged red or purple. The leaves are alternately arranged, 5-20 mm long sometimes up to 50 mm long, and 2–10 mm wide sometimes to 20 mm wide. Leaves have conspicuous pale veins, and are variable in shape and can be lanceolate (lance shaped, about 4 times as long as broad, broadest in the lower half and tapering to the tip) or ovate (egg-shaped attached to the stem at the wider end), obovate (egg-shaped attached to the stem at the thinner end). Leaves are petiolate (with leaf stalk) with larger leaves with long leaf stalk and sorter leaves with mostly short leafstalk, or subsessile (with a very short to almost absent leaf stalk). Leaf tips are obtuse (blunt or rounded, converging edges making an angle of more than 90°) to slightly emarginate (notched at apex, with notch usually broad and shallow), and sometimes mucronate (blunt with a thin sharp point).
Flowers located between most leaves, in few flowered (2–5) clusters 2–5 mm long. Flower 1–3 mm long, parts in 3s, surrounded by slightly longer (about 3 mm) spiny long bracts (a modified leaf associated with flower or inflorescence, differing from other leaves), 2 mm long bracteoles (smaller bract borne singly or in pairs, on pedicel or calyx). Both bracts and bracteoles are spinescent (ending in a spine). 3 petals oblong (Length a few times greater than width, with sides almost parallel and ends rounded) to spathulate (spoon-shaped; broad at the tip and narrowed towards the base), 1–2 mm long, acute (sharply pointed), with 3 stamens.
Fruit is a membranous capsule that is circumsciss (splitting around the middle, the upper part coming off like a lid) or rarely splitting irregularly (only recorded from plants in the Barmah Forest and Springhurst, Victoria only). Fruits are 1-2 mm long, globose (nearly spherical) and finely wrinkled or blistered. Inside the fruit us a shiny brown to black seeds that are lens-shaped and about 1 mm in diameter (Auld & Medd 1987; VicFlora 2016).
For further information and assistance with identification of Tumbleweed, contact the herbarium in your state or territory.
White, Yellow, Green
Tumbleweed (Amaranthus albus) is naturalised in temperate to semiarid areas of Australia, although now found in sub-tropical humid areas such as southern Queensland. It is a weed of cultivation and wasteland, stream banks, roadsides and railway lines (Auld & Medd 1987; Walsh 1996; Department of Primary Industries and Water 2007). Tumbleweed is sometimes found in coastal areas or fringing salt lakes in southern Victoria (Walsh 1996).
Across its native range in the United States of America, Tumbleweed prefers dry barren areas with scant vegetation such as the dry gravel prairies and sand prairies that are found in Illinois (Hilty 2002-2006) so it is possible that it could expand its range into drier regions of Australia.
Tumbleweed could be mistaken for Fat Hen (Chenopodium album). Fat Hen has a similar growth form but the branches are less rigid; the leaves are toothed along the margins rather than entire/not toothed, the flowers are clustered in heads in the leaf axils as well as at the end of the branches and are not surrounded by spiny bracts.
Prickly Saltwort or Roly-poly (Salsola australis) is also similar, having a rigid habit, spiny bracts around flowers and the habit of breaking off at the base once mature to roll around in the wind. It differs in having quite narrow, often succulent leaves, bracts around the flowers that are similar to the leaves and the flowers mature into a winged fruit that does not evenly split open like that of Tumbleweed (Palmer 2007, pers. comm.).
Tumbleweed (Amaranthus albus) is a common weed in southern Australia from higher rainfall to in drier areas, but sometimes coastal or fringing salt lakes. It is a common weed of agricultural areas and habitation, and can form dense stands. Also a weed of disturbed areas by stream and creek banks, roadsides, along railway-lines and corridors, and waste ground, and also in some native vegetation types. Normally inland in from higher rainfall to in drier areas, but sometimes coastal or fringing salt lakes.
Agriculture: Tumbleweed is a serious weed of agriculture (Tasmania DPIW 2007) and crops. Each plant, depending on its size, can produce tens of thousands of seeds that can persist as a weed seed bank over several crop rotations (Costea & Tardif 2003).In North America it has been recorded as a host to various fungal and viral diseases, nematodes and insects that can cause considerable damage to crop plants (Costea & Tardif 2003). This has not been documented as yet in Australia but has the potential to be a problem for crops that are badly infested with Tumbleweed.
Native ecosystems: Invades native vegetation normally open or degraded areas, especially so when those areas are surrounded by heavily infested agricultural or modified environments.
Urban areas: Known to be common along transport corridors (roadsides, railway lines, tracks and by waterways). Is a weed of waste and abandoned areas and gardens.
The main dispersal mechanism of Tumbleweed is the fruit capsule that splits around the middle when mature, allowing the seed to fall to the ground. Mature plants may also break off at the base and roll around in the wind across open ground distributing the seeds (Auld & Medd 1987; Hilty 2002-2006). Seeds can also be spread by the movement of contaminated soil and gravel due to earth works, and on wet soil on machinery, vehicles, and people.
No documented evidence is available to indicate how, when or why Tumbleweed arrived in Australia. However, herbarium specimens dating from the late 1880s from the Wimmera district in Victoria, and 1890s from Dubbo in central New South Wales indicate that it has been present in Australia since at least that time (AVH 2021).
There is limited information on Tumbleweed (Amaranthus albus) best practice management, but it is generally recommended that Tumbleweed is managed like any other summer growing annual dicot.
Chemical control: In general Amaranthus species are susceptible to a variety of selective and non-selective herbicides but resistant biotypes have been reported (Costea & Tardif 2003). Please see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au
Non-chemical control: Physical control: is used especially in agriculture.
Hand pulling: Small infestations and individual plants may be removed by hand pulling or digging out, when small populations or areas are involved
Mechanical control: In the United States of America mowing or tillage has been suggested as useful methods of control (Nelson 2005-2007).
Tumbleweed is a summer annual, flowering and fruiting from mid-summer to early autumn, or as early as December to as late as May. The flowers are wind pollinated. Once mature, the fruit split open and shed the seed (Paczkowska 1996; Walsh 1996; Hilty 2002-2006).
ACT, NSW, QLD, SA, TAS, VIC, WA
Tumbleweed (Amaranthus albus) occurs from in urban and modified landscapes and on edges of native vegetation (AVH 2021).
Tumbleweed occurs throughout the tablelands and slopes of New South Wales (Auld & Medd 1987).
In Queensland it is only known from urban areas.
In all regions of Victoria except areas of higher altitude, the Lowan Mallee in the west and Wilsons Promontory to the south (Walsh 1996),
Occurs in the south-west of Western Australia from Geraldton in the north to Albany and Esperance in the south (Paczkowska 1996), and in
In South Australia from the Flinders Ranges in the north down to the south-east (eFloraSA 2021).
In Tasmania, occurs in scattered localities in the north-west, north, midlands and to the south (Department of Primary Industries and Water 2007).
Tumbleweed is native to southern North America but can also be weedy or invasive in its home range (USDA, NRCS 2007).
White Pigweed, Stiff Tumbleweed