Xanthium is from the Greek xanthos meaning yellow and to its ancient use as a yellow hair dye.
Occidentale is from Occident meaning west and refers to its origin in the western hemisphere in North America.
Noogoora Burr refers to its first recordings at Noogoora station in Queensland and its burr like fruit.
Other names:
Beach Cocklebur (USA)
Beesklits (South Africa)
Burrweed
Cats Eggs
Clotbur
Cocklebur (North America, South Africa)
European Cockle Burr
Italian Cockle Burr (USA)
Kankeroos (South Africa)
Large Cockle Burr (South Africa)
Rough Cocklebur (Europe)
Sheepburr.
Summary:
A perennial shrub with large, rough, bristly, lobed leaves of similar shape to grapevine leaves. It has spineless stems and burrs with many hooked spines and 2 straight, parallel spines on top.
Description:
Cotyledons:
Two. Dull green, long and narrow, 25-50 mm long by 6-12 mm wide, thick smooth, tender, rounded tipped, broadest below the middle. Base tapered. Hairless. Petiole merging, thick, flattened and short on a soft sappy stalk. The seedling has a distinct hypocotyl and epicotyl.
First leaves:
Thinner, toothed and with short bristly hairs.
Leaves:
Lower leaves often opposite, upper leaves alternate.
Stipules - None.
Petiole - Stiff, 25-200 mm long, grooved.
Blade - Egg shaped to triangular, notched or abruptly narrowed base, 50-180 mm long by 50-150 mm wide with 3-5 palmate, irregularly toothed lobes, darker green on upper surfaces. Tip rounded to pointed. Obvious, reddish or purple veins. Similar shape to grape leaves. Tiny bristly and glandular hairs, rough to touch.
Stems:
Erect, woody, coarse, 250-2500 mm tall, often zigzag, streaked or blotched with purple especially on the young stems. Two forms; single, upright stem or many branched, bushy form. Short, upward directed bristles.
Flower head:
Unisexual.
Male and female flower heads together in clusters in the upper leaf axils and at the ends of stems. Females develop into burrs.
Male flower heads(involucre) has 1 row of free bracts.
Female flower heads egg shaped, 2 flowered, several rows of bracts with lowest row free and the upper rows forming a spiny burr when in fruit.
Flowers:
Inconspicuous.
Ovary - Receptacle has narrow, chaffy scales. Style with two long slender, flattish branches.
Perianth - Egg shaped near the top, tubular near the base, 5 toothed, no ligules.
'Petals' - None.
Stamens - 5
Anthers - 5, free, rounded at the base.
Fruit:
In clusters of 2-13 in the leaf axils towards the top of the stems.
Fruiting heads oval to oblong, 12-25 mm long, dark brown, hard woody, sparsely hairy, 2 nearly straight, nearly parallel spines(beaks) at the top, 2 seeded(achenes), many spines. Spines stout, up to 3 mm long, hooked.
Seeds:
Brown to black, flat on one side, 6-10 mm long, enclosed in achenes that are enclosed in the burr. 2 seeds in each burr with one larger than the other.
Roots:
Strong taproot to 800 mm deep and many branching laterals covering an area about 500 mm in diameter.
Key Characters:
No milky sap.
Leaves alternate, leaf blades about as broad as long.
Stems without spines.
Head unisexual, monoecious,
Fruiting heads dark brown, terminal beaks approximate with almost straight tips.
Female head 2 flowered, involucre bracts connate, hardened, enclosing the fruiting heads.
Involucre of male flowers consisting of free bracts.
Flowers not ligulate.
Receptacle with chaffy scales.
Style branches flattish.
Corolla tubular in male flowers, absent or reduced in females.
Anthers free, obtuse at base.
Spines stout up to 3 mm long.
No pappus.
From J.M. Black.
Biology:
Life cycle:
Annual. Seeds germinate mainly in the spring with some in summer and autumn. Its grows mainly in summer, flowers in late summer and dies off by autumn but remains standing and carrying burr for many months. Late germinating plants produce burr very quickly when they are still quite small and may be only a few centimetres tall.
Physiology:
Flooding tolerant.
It may set seed without fertilisation, so plants in an area often tend to be nearly identical but different to those from other areas.
Reproduction:
By seed.
Flowering times:
February to May or until June in tropical areas.
Late summer in SA.
Flowering is controlled by day length and occurs after the longest day of the year.
Seed Biology and Germination:
There are 2 seed in each burr and the upper one germinates in the following season while the lower one remains dormant for 2 or more years. It has several types of dormancy (enforced, innate and induced) making control difficult.
Buried burr has a higher germination percentage.
Vegetative Propagules:
None.
Hybrids:
It is a variable species with many forms.
Allelopathy:
Contains chemicals that reduce the growth or germination of companion plants.
Population Dynamics and Dispersal:
It is distributed mainly by sheep carrying burrs in their fleece and burrs floating along watercourses. The spiny burrs readily entangle in fur and fabric. Burrs have been seen on second hand bags and woolpacks and in mud on vehicles and international containers.
It is also spread by native animals, in agricultural seeds and produce and by earth moving operations.
It has been imported into Queensland in cotton seed. A related species California Burr (Xanthium orientale) was imported into SA in the rootstocks of grapes.
Infestations of up to 30 plants/m2 and allelopathic effects exclude most other species.
They readily colonise disturbed areas.
Origin and History:
Eastern North America. West Indies.
Probably introduced to Australia at Noogoora station, in Queensland, in the 1860's as a contaminant of cotton seed. By 1879, 200 ha was infested and it was in NSW by the 1890's. Major floods in the 1950's, 60's and 70's caused extensive spread in NSW with resulting in patches up to 5000 ha.
First recorded in Victoria in 1911 and controlled then appeared along the Murray in the 1920's and despite control is still present.
Recorded in South Australia in 1916 and eradicated, but reinfested in 1959 when large numbers or sheep were imported that had Noogoora Burr in their wool. It has since been controlled apart from occasional infestations and a large infestation at Lake Torrens.
There are several river systems infested in the Northern Territory and some are controlled.
In Western Australia 50,000 ha is infested on 14 properties and most of this is under a control program. All stock entering WA are inspected for burrs.
Probably introduced to Tasmania in wool. Only one infestation of Noogoora Burr has been found in recent years in Tasmania, in Launceston and has been eradicated.
Distribution:
Mainly in the Ord and Fitzroy River valleys of the Kimberly with occasional plants appearing in the south west of WA.
NSW, NT, QLD, SA, TAS, VIC, WA.
Courtesy Australia's Virtual Herbarium
Habitats:
Prefers open situations.
Climate:
Temperate areas with summer rainfall, irrigation or moisture.
Semi arid water courses. Sub tropical areas.
Soil:
More abundant on fertile soils.
Plant Associations:
Significance:
Considered to be the worst weed of Queensland.
Beneficial:
Grazed during droughts.
Used as a herbal remedy for fevers and as a diuretic and tonic.
Detrimental:
Weed of streams, flooded flats, pasture, summer crops, summer fallows and disturbed areas.
It is one of the main causes of vegetable fault in wool in Australia. Burrs cannot be removed from wool by normal mechanical or combing methods and wool requires carbonising with acid. 16% of the Queensland wool clip and 7-8% of the clip from eastern Australia contains burrs. The estimated loss is just under $2M per year.
Burrs interfere with shearing by jamming hand pieces and matting wool. They damage wool carding machines.
Contaminated wool is discounted 5-15% and a cost of 15c/kg is charged for cleaning.
Dense growth smothers pasture species.
Dense infestation may restrict access to stock watering points.
May cause lameness and infection in the feet of cattle.
It hosts Sclerotinia diseases overseas.
Toxicity:
The seedlings are poisonous to stock, especially cattle and pigs in spring and early summer. The main toxin is in the highest concentration in the cotyledons.
Pollen causes hay fever.
Stock and people can get dermatitis from contact with the plant.
Symptoms:
Animals often die overnight.
Excitement, salivation, nervousness, rapid weak pulse, trembling, gut pain, stilted gait, scouring, vomiting(in pigs), convulsions then death from 2 hours to several days after ingestion.
Treatment:
Don't allow cattle and pigs to graze areas infested with seedlings.
Legislation:
Declared plant that is under an eradication program in WA.
Noxious and prohibited weed of Tasmania.
Management and Control:
Cultivation provides effective control of vegetative plants. Burning is also effective in some situations. Hormone herbicides provide good control of young actively growing plants and there are several selective herbicides available for a number of crops.
Thresholds:
Less than 1 plant/m2 is usually worth spraying.
Eradication strategies:
Check all imports of stock, fodder, grain, produce and bags for burrs. Prevent seed set. Don't allow stock and especially sheep to have access to infested areas when burrs are present.
Isolated plants should be manually removed and the area sprayed with a mixture of 1 litre of Tordon 75-D in 100 litres of water each spring for several years.
If seed production is eliminated it will still take 6 years to reduce seed banks to 1% of their original levels.
Control programs should start at the headwaters of catchments.
Herbicide resistance:
Biological Control:
A number of agents are providing some level of control.
Related plants:
Bathurst Burr (Xanthium spinosum) is smaller, more branched and has narrower dark green leaves that are whitish underneath and the stems has long, yellow, three-pronged spines.
Californian Burr (Xanthium orientale)is very similar but has 2, hooked horns at the top of the burr.
Xanthium ambrosioides is very similar.
Xanthium cavanillesii is very similar.
Xanthium italicum is very similar.
Plants of similar appearance:
References:
Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P121. Diagrams. Photos.
Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P874. Diagram of fruit.
Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney). P192-4. Plate 14.
Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (1997). Western Weeds. A guide to the weeds of Western Australia. (Plant Protection Society of Western Australia, Perth, Western Australia). P108. Photo.
Hyde-Wyatt, B.H. and Morris, D.I. (1980) The Noxious and Secondary Weeds of Tasmania. (Tasmanian Department of Agriculture, Hobart, Tasmania). P23. Diagrams.
Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).
Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #1286.2.
