Xanthium strumarium (common cocklebur)
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- Habitat List
- Hosts/Species Affected
- Host Plants and Other Plants Affected
- Biology and Ecology
- Natural enemies
- Notes on Natural Enemies
- Threatened Species
- Risk and Impact Factors
- Uses List
- Similarities to Other Species/Conditions
- Prevention and Control
- Links to Websites
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Xanthium strumarium L. (1753)
Preferred Common Name
- common cocklebur
Other Scientific Names
- Xanthium abyssinicum Wallr.
- Xanthium brasilicum Velloso
- Xanthium californicum E.L. Greene
- Xanthium canadense Mill., 1768
- Xanthium canavillesii Schouw., 1849
- Xanthium chinense Mill.
- Xanthium echinatum Murray, 1784
- Xanthium indicum Klatt, 1880
- Xanthium italicum Moretti
- Xanthium macrocarpum DC
- Xanthium occidentale Bertol.
- Xanthium orientale L. 1763
- Xanthium pensylvanicum Wallr. 1844
- Xanthium pungens Wallr. 1844
- Xanthium ripicola
- Xanthium sibiricum Patrin ex Widder, 1923
- Xanthium strumarium var. canadense (Mill.) Torr. & A. Gray
- Xanthium varians Greene
- Xanthium vulgare Hill
International Common Names
- English: clotbur; cocklebur; ditchbur
- Spanish: Chayotillo
- French: lampourde glouteron
- Portuguese: bardana-menor
Local Common Names
- Australia: noogoora bur; sheep bur
- Germany: Stachel- Spitzklette
- India: adhisishi; bada gokhru bhakra; chota dhatura
- Italy: lappola comune
- Japan: onamomi
- Malaysia: buah anjang
- Netherlands: ongedoornde stekelnoot
- Pakistan: puth kando
- South Africa: kankerroos
- Taiwan: tsai-er
- Thailand: kachab
- Turkey: siraco out
- XANPU (Xanthium pungens)
- XANST (Xanthium strumarium)
Summary of InvasivenessTop of page
The following summary is from Witt and Luke (2017):
Annual much-branched herb with erect stems (20–150 cm high) without spines; stems stout, green, brownish or reddish-brown, roughly hairy.
Uncertain, but probably Central and South America.
Reason for Introduction
Bee forage and accidentally as a contaminant.
Roadsides, wasteland, disturbed land, fallow land, crops, plantations, drainage ditches, savannahs, water courses, lowlands, floodplains and sandy dry riverbeds.
Rapidly forms large stands, displacing other plant species. X. strumarium is a major weed of row crops such as soybeans, cotton, maize and groundnuts in many parts of the world, including North America, southern Europe, the Middle East, South Africa, India and Japan. It also has a damaging impact on rice production in Southeast Asia. Cocklebur is also an alternative host for a number of crop pests. X. strumarium burrs lodge in animal hair and in sheep’s wool, reducing the quality and increasing treatment costs. The plants are toxic to livestock and can lead to death if eaten.
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Spermatophyta
- Subphylum: Angiospermae
- Class: Dicotyledonae
- Order: Asterales
- Family: Asteraceae
- Genus: Xanthium
- Species: Xanthium strumarium
Notes on Taxonomy and NomenclatureTop of page The revised classification of Xanthium taxa by Love and Dansereau (1959) reduced the number of Xanthium species to two: X. strumarium and X. spinosum. The numerous species of Xanthium reported in the literature, other than X. spinosum, are now considered forms of X. strumarium. This is an extremely variable species comprising at least two subspecies (for example, X. strumarium var. canadense) and a group of complexes within each, differing in geographic distribution and bur morphology. There are no sterility barriers between subspecies or complexes (Love and Dansereau, 1959; McMillan, 1974; 1975). All these Xanthium taxa are tetraploid with a chromosome number of 2n = 36 (Love and Dansereau, 1959). The related species X. spinosum is more homogeneous throughout its range than X. strumarium. Hybrids between the two species can occur (Love, 1976).
DescriptionTop of page X. strumarium is a coarse, erect, branching, annual herb which reproduces solely by seed; stems 30 to 150 cm tall, tough, with short dark streaks or spots and covered with short hairs which give a coarse texture; leaves alternate, triangular-ovate to broadly ovate in shape, 2 to 12 cm long, base often cordate, petiole 2 to 8 cm long, margins irregularly toothed or lobed, both surfaces rough-pubescent; flowers monoecious, male flowers inconspicuous, many-flowered heads 5 to 8 mm across, clustered at the tips of branches or axillaries above the female flowers, female flower heads axillary, greenish, two flowers in the head enclosed by the involucre; fruit, a hard brown, ovoid bur, 1.5 to 2.5 cm long, covered with hooked spines 2 to 4 mm long, and with two terminal beaks, fruits readily stick to clothing and fur, and thus are easily spread; seeds (achenes) black, two in each bur, one above the other (from Holm et al., 1977).
DistributionTop of page The geographic distribution of X. strumarium extends from latitude 53°N to 33°S (Holm et al., 1977). It is most often found in the temperate zone, but also occurs in subtropical and Mediterranean climates. Love and Dansereau (1959) identified the centre of origin of X. strumarium as Central or South America. The native North American Xanthium taxa originally grew along shores and rivers and the fruits were dispersed by water or occasionally by animals.
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|China||Widespread||Wang, 1990; Holm et al., 1991; Li ChangTian, 2012|
|-Xinjiang||Present||Invasive||Du et al., 2012|
|India||Widespread||Holm et al., 1991|
|Iran||Widespread||Holm et al., 1991|
|Iraq||Widespread||Holm et al., 1991|
|Israel||Widespread||Holm et al., 1991|
|Japan||Widespread||Holm et al., 1991|
|Lebanon||Widespread||Holm et al., 1991|
|Pakistan||Present||Holm et al., 1991|
|Philippines||Present||Holm et al., 1991|
|Taiwan||Widespread||Holm et al., 1991|
|Thailand||Present||Holm et al., 1991|
|Turkey||Present||Holm et al., 1991|
|Botswana||Present||Introduced||Invasive||Wells et al., 1986; Witt and Luke, 2017|
|Burundi||Present||Introduced||Witt and Luke, 2017||Naturalized|
|Egypt||Present||Ibrahim et al., 1988|
|Ethiopia||Present||Invasive||Holm et al., 1991; Mohammed and Tamrat, 2010; Witt and Luke, 2017|
|Kenya||Present||Introduced||Invasive||Witt and Luke, 2017|
|Lesotho||Present||Wells et al., 1986|
|Malawi||Present||Introduced||Invasive||Witt and Luke, 2017|
|Rwanda||Present||Introduced||Witt and Luke, 2017||Nauralized|
|South Africa||Widespread||Wells et al., 1986; Holm et al., 1991|
|Tanzania||Present||Introduced||Invasive||Witt and Luke, 2017|
|Uganda||Present||Introduced||Invasive||Witt and Luke, 2017|
|Zambia||Present||Introduced||Invasive||Witt and Luke, 2017|
|Canada||Widespread||Weaver & Lechowicz, 1983|
|-Alberta||Restricted distribution||Weaver & Lechowicz, 1983|
|-British Columbia||Restricted distribution||Weaver & Lechowicz, 1983|
|-Manitoba||Restricted distribution||Weaver & Lechowicz, 1983|
|-New Brunswick||Restricted distribution||Weaver & Lechowicz, 1983|
|-Nova Scotia||Restricted distribution||Weaver & Lechowicz, 1983|
|-Ontario||Present||Weaver & Lechowicz, 1983|
|-Prince Edward Island||Present||Weaver & Lechowicz, 1983|
|-Quebec||Present||Weaver & Lechowicz, 1983|
|-Saskatchewan||Present||Weaver & Lechowicz, 1983|
|USA||Widespread||Holm et al., 1991|
Central America and Caribbean
|Trinidad and Tobago||Present||Holm et al., 1991|
|Czechoslovakia (former)||Present||Love, 1976|
|Greece||Present||Love, 1976; Thanassoulopoulos et al., 1981|
|Hungary||Present||Love, 1976; Holm et al., 1991|
|Italy||Present||Love, 1976; Sartorato et al., 1996|
|Poland||Present||Holm et al., 1991|
|Russian Federation||Present||Holm et al., 1991|
|-Central Russia||Present||Love, 1976|
|-Northern Russia||Present||Love, 1976|
|-Southern Russia||Present||Love, 1976|
|Spain||Widespread||Holm et al., 1991|
|-Balearic Islands||Present||Love, 1976|
|Yugoslavia (former)||Widespread||Love, 1976; Holm et al., 1991|
|Australia||Widespread||Holm et al., 1991|
|-Australian Northern Territory||Present||Lazarides et al., 1997|
|-New South Wales||Present||Lazarides et al., 1997|
|-Queensland||Present||Lazarides et al., 1997|
|-South Australia||Present||Lazarides et al., 1997|
|-Victoria||Present||Lazarides et al., 1997|
|-Western Australia||Present||Lazarides et al., 1997|
|New Zealand||Present||Webb, 1987|
|Papua New Guinea||Present||Henty and Pritchard, 1975|
HabitatTop of page X. strumarium tolerates a wide variety of soil types and textures and a soil pH range of 5.2 to 8.0, as well as frequent flooding and saline conditions (Weaver and Lechowicz, 1983). It occurs in cultivated fields, along beaches, coastal dunes, watercourses, railway embankments, roadsides, field edges, and waste places. It prefers open communities and will disappear if shaded or crowded (Kaul, 1971). It is not common in mountainous regions.
Habitat ListTop of page
Hosts/Species AffectedTop of page X. strumarium is a very common weed of many row crops in the temperate and subtropical regions of the world. Some forms of X. strumarium are found only along coastal beaches and watercourses, rather than as weeds of crops.
Host Plants and Other Plants AffectedTop of page
|Arachis hypogaea (groundnut)||Fabaceae||Main|
|Beta vulgaris (beetroot)||Chenopodiaceae||Main|
|Colocasia esculenta (taro)||Araceae||Other|
|Glycine max (soyabean)||Fabaceae||Main|
|Gossypium hirsutum (Bourbon cotton)||Malvaceae||Main|
|Helianthus annuus (sunflower)||Asteraceae||Other|
|Oryza sativa (rice)||Poaceae||Other|
|Phaseolus vulgaris (common bean)||Fabaceae||Other|
|Saccharum officinarum (sugarcane)||Poaceae||Main|
|Sorghum bicolor (sorghum)||Poaceae||Main|
|Triticum aestivum (wheat)||Poaceae||Other|
|Zea mays (maize)||Poaceae||Main|
Biology and EcologyTop of page Seed germination and emergence of X. strumarium generally occurs in late spring or early summer. The two seeds within each bur often differ in size and dormancy status, with the larger seed germinating in the spring following production, and the smaller seed germinating a year later (Kaul, 1965). Light is not required for germination and seedlings seldom emerge from seeds lying on the soil surface or from those buried 15 cm or more below the soil surface (Stoller and Wax, 1974). Seed production is strongly correlated with above-ground biomass at the time of floral initiation. Vigorous, open-grown plants can produce from 500 to 2300 burs per plant (Weaver and Lechowicz, 1983). The spiny burs are readily dispersed by adhering to animals, human clothing or other materials, as a contaminant of wool, and by water. Viability of seeds buried in the soil does not generally exceed five years (Weaver and Lechowicz, 1983).
X. strumarium is a short-day plant which generally will not flower under photoperiods longer than 14 hours, although populations vary in critical night length with latitude of origin (Ray and Alexander, 1966; McMillan, 1975). X. strumarium has the C3 pathway of photosynthesis. It is self-compatible and primarily wind-pollinated.
Natural enemiesTop of page
|Natural enemy||Type||Life stages||Specificity||References||Biological control in||Biological control on|
|Zygogramma bicolorata||Predator||Growing point/Inflorescence/Leaves|
Notes on Natural EnemiesTop of page A wide range of herbivores, pathogens and seed predators have been recorded on X. strumarium, however, they do not generally provide complete control.
ImpactTop of page X. strumarium is a major weed of row crops such as soyabeans, cotton, maize and groundnuts in many parts of the world, including North America, southern Europe, the Middle East, South Africa, India and Japan. In 1995, it ranked as the fourth, fifth, sixth and seventh most troublesome weed in soyabean, cotton, maize and groundnut, respectively, across 10 southern states in the USA. Between 1974 and 1995, X. strumarium decreased in importance in maize, soyabean and groundnuts in the southern USA, but increased in cotton (Webster and Coble, 1997). These rankings were based on distribution, abundance and difficulty of control.
In soyabeans, cocklebur has been reported to cause the highest reductions in yield of all annual weeds in both northern and southern production areas of the USA (Stoller et al., 1987). Soyabean yield losses are estimated at 10 to 16% for 0.5 plants of X. strumarium per m of row, 65% for 4 plants and 80% for over 10 plants per m of row, for weeds emerging at the same time as the crop (Stoller et al., 1987; Rushing and Oliver, 1998). Similar yield losses from cocklebur were reported in Ontario, Canada (Weaver, 1991). In Italy, Sartorato et al. (1996) recommended an economic threshold of only 0.05 plants of X. strumarium per square m in soyabeans. In addition to direct yield losses through competition, infestations of X. strumarium decrease soyabean seed quality and harvesting efficiency. One cocklebur per m of row was shown to cause a 7.2% increase in foreign material in harvested soyabeans, a 5.2% increase in seed moisture content, decreased test weight by 58.6 g/L seed, and reduced combine speed (Ellis et al., 1998). The authors recommended use of a pre-harvest desiccant when cocklebur densities exceeded 0.5 plants per m of row.
In cotton in the USA, seed yield losses of 60 to 90 kg/ha (approximately 5%) have been reported from cocklebur growing at a density of one plant per 15 m of row in Mississippi (Snipes et al., 1982). Cotton yield losses from one plant of X. strumarium per 3 m of row varied from 6 to 27% in North Carolina (Byrd and Coble, 1991). The critical period for cocklebur in cotton lasted from 2 to 10 weeks after cotton emergence (Snipes et al., 1987).
In groundnuts, cocklebur has been reported to cause yield losses of 31-39% at a density of 0.5 plants and 88% at 4 plants per m of row in the southern USA (Royal et al., 1997a, b). Cocklebur densities higher than 1 plant per 2 m of row reduced deposition of the fungicide chlorothalonil by 34% (Royal et al., 1997b).
The economic impact of X. strumarium in maize is somewhat lower than for soyabeans, cotton and groundnuts. Yields of maize in Illinois, USA have been reported to decrease by 10% at 1 cocklebur per m of row, to a maximum yield loss of 27% at a density of 4.7 cockleburs per m of row (Becket et al., 1988).
Infestations of X. strumarium can also cause significant yield losses in horticultural row crops (Weaver and Lechowicz, 1983). In snap beans, yield losses of 5 to 50% were reported for densities of X. strumarium ranging from 0.5 to 8 per square m (Neary and Majek, 1990).
X. strumarium also has a detrimental impact on livestock production which has been best documented in Australia, where it is abundant in sheep-grazing regions in the eastern half of the continent in Queensland and New South Wales (Wapshere, 1974; Hocking and Liddle, 1986). The burs lodge in animal hair and sheep wool, and are difficult to remove when the wool is processed after shearing. Contaminated wool requires special treatment and may have a price penalty of 25% or more (Wapshere, 1974). The prickly burs can cause considerable discomfort to animals by clinging to hair on the legs and matting the tails and manes of horses.
X. strumarium also has an economic impact in pastures, where cattle, sheep and pigs may be poisoned by eating young plants. The cotyledons contain a toxic compound, carboxyatractyloside, which is absent in older plants (Weaver and Lechowicz, 1982; Hocking and Liddle, 1986; Martin et al., 1992). Symptoms include vomiting, muscular spasms, liver degeneration and occasionally death.
Cocklebur serves as a host for a number of pathogens of crops. Sunflowers have been reported to be damaged by the rust Puccinia xanthii, commonly found on cocklebur, and by alternaria leaf spot (Alternaria helianthi), also found on cocklebur in North America (Hocking and Liddle, 1986). Cocklebur is reported to be a host for Sclerotinia minor and S. sclerotiorum which contaminate soyabean and discolour seed and result in a lowered price (Hocking and Liddle, 1986). X. strumarium is also an alternate host for the insect Spilosoma obliqua (Lepidoptera) which attacks Egyptian clover in India (Dhaliwal, 1993), and for Colletotrichum capsici, which causes anthracnose on tomato fruit and cotton seedlings in the USA (Mclean and Roy, 1991).
The Xanthium genus is closely related to the Ambrosia (ragweed) genus, and X. strumarium produces large amounts of highly antigenic pollen (Reddi et al., 1980). The glandular hairs on the leaves and stem secrete a substance which causes contact dermititis in allergic individuals (King, 1966).
Threatened SpeciesTop of page
|Threatened Species||Conservation Status||Where Threatened||Mechanism||References||Notes|
|Schiedea apokremnos (Kauai schiedea)||CR (IUCN red list: Critically endangered) CR (IUCN red list: Critically endangered); USA ESA listing as endangered species USA ESA listing as endangered species||Hawaii||Competition (unspecified)||US Fish and Wildlife Service, 2010|
Risk and Impact FactorsTop of page Impact mechanisms
UsesTop of page X. strumarium, has been used for various medicinal purposes, including the treatment of malaria in India (Mitich, 1987; Talakal et al., 1995). The genus name is derived from the Greek root 'Xanthos' which means 'yellow', and the plant may once have been used to produce a dye (Weaver and Lechowicz, 1982).
Uses ListTop of page
- Poisonous to mammals
Similarities to Other Species/ConditionsTop of page X. strumarium resembles X. spinosum, but the latter species has stout, three-pronged spines at the stem nodes and in the leaf axils. X. spinosum is primarily a weed of pastures or meadows, although it may occur as a minor weed of row crops. It is also a native of South America, and its range extends from latitude 50°N to 43°S (Holm et al., 1977). X. strumarium is quite common in Australia, and is also found in parts of North and South America, Europe and the Mediterranean.
Both species are sometimes confused with burdocks (Arctium spp.). The latter are biennials which produce a rosette of large leaves during their first year, and spherical burs densely covered with hooked spines during their second year.
Prevention and ControlTop of page
Seedlings of X. strumarium can be controlled by cultivation, but older plants often produce shoots from axillary buds if the root has not been severed. Adoption of zero or reduced tillage systems can potentially reduce Xanthium populations, because burs seldom germinate on the soil surface (Vencill and Banks, 1994).
X. strumarium is controlled by many soil-applied and foliar herbicides. In France, Mamarot and Rodriguez (1997) give recommendations for a range of treatments including sulcitrone in maize, amitrole directed in maize, bentazon and fomesafen in soyabeans.
In Brazil, Lorenzi (1984) tabulates susceptiblity to bentazon, dicamba, 2,4-D and glyphosate, but states that the weed is resistant to metolachlor, asulam, butachlor, butylate,cyanazine, linuron, oxadiazon, pendimethalin, trifluralin and vernolate. In Papua New Guinea, Henty and Pritchard (1975) indicate susceptibility to 2,4-D, MCPB, amitrole, ametryne and diuron recommended for broad-leaved weeds, including atrazine, dicamba, metribuzin, bentazon, acifluorfen, and imazethapyr.
Populations resistant to imidazolinones and to the arsenical herbicides MSMA/DSMA have been reported in the USA (Heap, 1997).
Biological control of X. strumarium has been attempted with Alternaria helianthi (Abbas and Barrentine, 1995), and the rust Puccinia xanthii (Julien et al., 1979). Seed predation by the moth, Phaneta imbridana, and the trypetid fly, Euaresta aequalis, in the USA, may provide some control (Hare and Futuyma, 1978; Hare, 1980).
A. helianthi caused necrotic lesions on leaves of A. retroflexus, and resulted in 100% or 67% mortality of plants grown under growth chamber or outdoor conditions, respectively, when applied as a solution of conidia to seedlings (Abbas and Barrentine, 1995). The authors suggested that a phytotoxin could be isolated from A. helianthi and sprayed as a mycoherbicide.
The rust P. xanthii occurs in North America and India and was accidentally introduced into Australia (Hocking and Liddle, 1986). It causes deformation of the leaves, splitting of the petioles and stems, and finally leaf drop, but it has not provided significant large-scale control of X. strumarium.
Seed damage ranged from 0 to 28% for Phaneta imbridana, and from 0 to 42% for Euaresta aequalis, on natural populations of X. strumarium in New York. E. aequalis was introduced into Australia from North America in the 1930's. It became established only in the vicinity of Brisbane, and has not contributed significantly to the control of X. strumarium (Hocking and Liddle, 1986).
As summarized by Julien (1992), additional attempts at biological control have included: the lepidopteran Epiblema strenuana which was introduced from Mexico to Australia in 1984 and became widely established, reducing weed vigour and competiveness; Mecas saturnina (Coleoptera), introduced from N. America to Australia in 1963, but thought to have died out; and Nupserha vexator, introduced from India to Fuji and Australia, without notable success.
ReferencesTop of page
Dhaliwal JS, 1993. Role of some weeds in the carry-over of Spilosoma obliqua (Walker) to Egyptian clover (Trifolium alexandrinum L.). Journal of Research, Punjab Agricultural University, 30(3-4):168-170
Du ZhenZhu, Xu WenBin, Yan Ping, Wang ShaoShan, Guo YiMin, 2012. Three newly recorded alien invasive plants of Xanthium in Xinjiang. Xinjiang Agricultural Sciences, 49(5):879-886. http://www.xjnykx.periodicals.com.cn
Hare JD, Futuyma DJ, 1978. Different effects of variation of Xanthium strumarium L. (Compositae) on two insect seed predators. Oecologia, 37:109-120
Heap IM, 1997. International Survey of Herbicide-Resistant Weeds. Annual Report, Weed Science Society of America
Hocking PJ, Liddle MJ, 1986. The biology of Australian weeds: 15. Xanthium occidentale Bertol. complex and Xanthium spinosum L. Journal of the Australian Institute of Agricultural Science, 52(4):191-221
Kaul V, 1965. Physiological-ecology of Xanthium strumarium L. II. Physiology of seeds in relation to its distribution. Journal of Indian Botanical Society, 44:365-380
Kaul V, 1971. Physiological-ecology of Xanthium strumarium L. IV. Effect of climatic factors on growth and distribution. New Phytologist, 70:799-812
King LJ, 1966. Weeds of the World. Biology and Control. New York, USA: Interscience Publ
Love D, Dansereau P, 1959. Biosystematic studies on Xanthium: Taxonomic appraisal and ecological status. Canadian Journal of Botany, 37:173-208
Martin T, Johnson BJ, Sangiah S, Burrows GE, 1992. Experimental cocklebur (Xanthium strumarium) intoxication in calves. Poisonous plants. Proceedings of the Third International Symposium., 489-494; 16 ref
McMillan C, 1974. Experimental hybridization in Xanthium strumarium of American complexes with diverse photoperiodic adaptation. Canadian Journal of Botany, 52:849-859
McMillan C, 1975. Experimental hybridization of Xanthium strumarium (Compositae) from Asia and America. 1. Responses of F1 hybrids to photoperiod and temperature. American Journal of Botany, 62(1):41-47
Mohammed AS, Tamrat Bekele, 2010. Forage production and plant diversity in two managed rangelands in the Main Ethiopian Rift. African Journal of Ecology, 48(1):13-20. http://www.blackwell-synergy.com/loi/aje
Ray PM, Alexander WE, 1966. Photoperiodic adaptation to latitude in Xanthium strumarium. American Journal of Botany, 53:806-816
Reddi CS, Reddi EUB, Bai AJ, Raju KVR, Reddi MS, 1980. The ecology of anther dehiscence, pollen liberation and dispersal in Xanthium strumarium L. Indian Journal of Ecology, 7:171-181
Royal SS, Brecke BJ, Shokes FM, Colvin DL, 1997. Influence of broadleaf weeds on chlorothalonil deposition, foliar disease incidence, and peanut (Arachis hypogaea) yield. Weed Technology, 11(1):51-58; 18 ref
Sartorato I, Berti A, Zanin G, 1996. Estimation of economic thresholds for weed control in soybean (Glycine max (L.) Merr.). Crop Protection, 15:63-68
United States Department of Agriculture, 1970. Selected Weeds of the United States. Agriculture Handbook No. 366. Washington DC, USA: USDA
US Fish and Wildlife Service, 2010. Schiedea apokremnos (maolioli). 5-Year Review: Summary and Evaluation. In: Schiedea apokremnos (maolioli). 5-Year Review: Summary and Evaluation : US Fish and Wildlife Service.16 pp.
Witt, A., Luke, Q., 2017. Guide to the naturalized and invasive plants of Eastern Africa, [ed. by Witt, A., Luke, Q.]. Wallingford, UK: CABI.vi + 601 pp. http://www.cabi.org/cabebooks/ebook/20173158959 doi:10.1079/9781786392145.0000
Distribution MapsTop of page
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