Conyza bonariensis (hairy fleabane)
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Plant Type
- Distribution Table
- History of Introduction and Spread
- Risk of Introduction
- Habitat List
- Hosts/Species Affected
- Host Plants and Other Plants Affected
- Biology and Ecology
- Soil Tolerances
- Natural enemies
- Means of Movement and Dispersal
- Pathway Vectors
- Plant Trade
- Impact Summary
- Environmental Impact
- Threatened Species
- Social Impact
- Risk and Impact Factors
- Similarities to Other Species/Conditions
- Prevention and Control
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Conyza bonariensis (L.) Cronq. (1943)
Preferred Common Name
- hairy fleabane
Other Scientific Names
- Conyza ambigua DC.
- Conyza bonariensis var. leiotheca (S.F. Blake) Cuatrec.
- Conyza crispus (Pourr.) Rupr.
- Conyza linifolia (Willd.) Tackh.
- Erigeron bonariensis L. (1753)
- Erigeron crispus Pourr.
- Erigeron crispus subsp. naudinii (Bonnet) Bonnier
- Erigeron linifolius Willd. (1804)
- Leptilon bonariense (L.) Small
- Leptilon linifolium (Willd.) Small
International Common Names
- English: Argentine fleabane; fleabane
- Spanish: carnicera (Argentina); rama negra (Argentina); venadillo; yerba de la vida (Argentina); zamarraga
- French: erigéron de Bonard
- Portuguese: avoadinha-peluda; buva
Local Common Names
- Australia: flaxleaf fleabane
- Brazil: margaridinha-do-campo
- Germany: Krauser Katzenscweif; Krauses berufkraut
- Italy: ceppica campestre
- Japan: arechinogiku
- Netherlands: fijnstraal, vlasbladige
- New Zealand: wavy-leaf fleabane
- Norway: vlasbadige fiijnstraal
- USA: asthma weed; asthmaweed; hairy fleabane
- ERIBO (Erigeron bonariensis)
Summary of InvasivenessTop of page C. bonariensis is a mainly annual herbaceous weed overwinters as a rosette, and spreads by producing high numbers of wind-dispersed seeds. It prefers undisturbed sites and is a particular problem in low-tillage systems such as orchards and plantations but also in some agricultural crops. It may be controlled by tillage at a suitable growth stage, but otherwise, it has developed resistance to many herbicides in a large number of countries. It has been introduced internationally as a seed contaminant and there is a risk of further similar introduction to countries where it is not yet established. It could become a problem invasive in protected areas, though may be controlled naturally by succession.
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Spermatophyta
- Subphylum: Angiospermae
- Class: Dicotyledonae
- Order: Asterales
- Family: Asteraceae
- Genus: Conyza
- Species: Conyza bonariensis
Notes on Taxonomy and NomenclatureTop of page Originally decribed by Linnaeus as Erigeron bonariensis, the species was transferred to the genus Conyza by Cronquist in the mid 1900s, maintaining its species epithet. Conyza floribunda and C. sumatrensis are sometimes used as synonyms for C. bonariensis (e.g. Holm et al., 1979; Lorenzi, 1982; USDA-NRCS, 2004) but are now generally regarded as distinct species (for C. sumatrensis see the separate datasheet). Taxonomic confusion is continued with USDA-NRCS (2004) incorrectly noting C. bonariensis var. leiotheca and C. floribunda as synonyms of C. bonariensis; synonyms are used here according to the Royal Botanic Garden Edinburgh (2003). A further reason for confusion arises from Erigeron crispus subsp. naudinii being noted as a synonym, whereas C. naudinii is recorded a synonym of C. floribunda (Royal Botanic Garden Edinburgh, 2003). There also continues to be some confusion as to the placement of taxa into genera including Conyza, with, for example, USDA-ARS (2004) noting the existence of only eight species of Conyza, without mention of C. floribunda or C. triloba (Sida, 2003) even as non-preferred names.
DescriptionTop of page C. bonariensis is an erect annual with one or more stems from a basal rosette, up to 60 cm or occasionally 100 cm in height. All parts of the plant are finely pubescent and greyish in colour. Leaves linear to oblanceolate, mostly about 5 mm wide, entire, but often wavy-edged, with very short or hooked hairs less than 0.5 mm long. The inflorescence has long branches resulting in an almost corymbose effect, with most flowering heads about the same level. Individual flower heads are greyish-green, 4-5 mm diameter when fresh (broader in pressed specimens) with cream-coloured disc florets and no ray florets. The involucral bracts are pubescent with hairs almost as long as the bract width. The pappus is white or pinkish and 4-5 mm long; seeds are about 1 mm long.
Plant TypeTop of page Annual
DistributionTop of page C. bonariensis was first described from Argentina and is probably native to the more temperate parts of South America (Michael, 1977), but it is now widely spread through most warmer regions of Europe, Africa, Asia, the Caribbean and Central America. The situation in North America is somewhat confused, with USDA-NRCS (2004) noting a continuous distribution across the southern USA from California to Florida, north to Oregon, North Carolina and Virginia but not Hawaii or Puerto Rico; whereas USDA-ARS (2004) records presence only California in mainland USA, and Hawaii and Puerto Rico also. This may be explained by the use of C. floribunda as a synonym by USDA-NRCS (2004), thus these additional USA states records may belong to this species and not C. bonariensis in the sense used in this datasheet. Missouri Botanical Garden (2004) do note, however, presence in Lousiana, Mississippi and Florida in addition to California, indicating that the situation is not clear and requires resolution.
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|
|Afghanistan||Present||Introduced||Holm et al., 1979|
|Bahrain||Present||Introduced||Chaudhary et al., 1981|
|Bhutan||Indigenous, localized||Introduced||Parker, 1992|
|China||Present||Introduced||Holm et al., 1979|
|-Hong Kong||Present||Introduced||Michael, 1977|
|-Hunan||Present||Introduced||Xie and Yao, 1989|
|-Jiangsu||Present||Native||Wu and Qiang, 2003|
|-Shanghai||Present||Wang et al., 2007|
|-Shanxi||Present||Liu and Kang, 2008|
|-Zhejiang||Present||Hong et al., 2008|
|India||Widespread||Introduced||Holm et al., 1979|
|-Jammu and Kashmir||Present||Amit and Singh, 2005|
|-Tamil Nadu||Present||Victor et al., 2001|
|-Uttar Pradesh||Present||Satya and Kanchan, 2004|
|Indonesia||Widespread||Introduced||Holm et al., 1979|
|Iran||Present||Introduced||Fatehi et al., 1993|
|Israel||Widespread||Introduced||Holm et al., 1979|
|Korea, Republic of||Present||Introduced||Kim et al., 2003|
|Oman||Present||Introduced||Chaudhary et al., 1981|
|Saudi Arabia||Present||Introduced||Chaudhary et al., 1981|
|Taiwan||Present||Introduced||Holm et al., 1979|
|Turkey||Present||Introduced||Royal Botanic Garden Edinburgh, 2003; USDA-ARS, 2004|
|United Arab Emirates||Present||Introduced||Chaudhary et al., 1981|
|Yemen||Present||Introduced||Chaudhary et al., 1981|
|Botswana||Present||Introduced||Wells et al., 1986|
|Côte d'Ivoire||Present||Introduced||Adams, 1963|
|Egypt||Present||Introduced||Holm et al., 1979|
|Ethiopia||Present||Introduced||Stroud & Parker, 1979|
|Kenya||Widespread||Introduced||Holm et al., 1979|
|Lesotho||Present||Introduced||Wells et al., 1986|
|Morocco||Present||Introduced||Holm et al., 1979|
|Namibia||Present||Introduced||Wells et al., 1986|
|Sao Tome and Principe||Present||Introduced||Adams, 1963|
|South Africa||Present||Introduced||Holm et al., 1979|
|-Canary Islands||Present||Siverio et al., 2011|
|Swaziland||Present||Introduced||Wells et al., 1986|
|Tanzania||Present||Introduced||Holm et al., 1979|
|Uganda||Present||Introduced||Lind and Tallantire, 1971|
|Zimbabwe||Present||Introduced||Holm et al., 1979|
|Mexico||Present||Introduced||Invasive||Morgado-Arroya & Urzua-Soria, 1995|
|USA||Present||Present based on regional distribution.|
|-California||Present||Introduced||Invasive||Kempen and Graf, 1981|
|-Hawaii||Present||Introduced||Invasive||Holm et al., 1979|
Central America and Caribbean
|Jamaica||Present||Introduced||Invasive||Holm et al., 1979|
|Lesser Antilles||Present||Introduced||Not invasive||USDA-ARS, 2004|
|Puerto Rico||Present||Introduced||USDA-ARS, 2004|
|Trinidad and Tobago||Present||Introduced||Invasive||Holm et al., 1979|
|Argentina||Widespread||Native||Holm et al., 1979|
|Brazil||Widespread||Native||Holm et al., 1979|
|-Espirito Santo||Present||Native||Lorenzi, 1982|
|-Mato Grosso||Present||Native||Lorenzi, 1982|
|-Mato Grosso do Sul||Present||Native||Lorenzi, 1982|
|-Minas Gerais||Present||Native||Lorenzi, 1982|
|-Rio de Janeiro||Present||Native||Lorenzi, 1982|
|-Rio Grande do Norte||Present||Native||Lorenzi, 1982|
|-Rio Grande do Sul||Present||Native||Lorenzi, 1982|
|-Santa Catarina||Present||Native||Lorenzi, 1982|
|-Sao Paulo||Present||Native||Lorenzi, 1982|
|Chile||Present||Native||Finot et al., 1996|
|Colombia||Present||Native||Holm et al., 1979|
|Peru||Present||Native||Holm et al., 1979|
|Uruguay||Present||Native||Holm et al., 1979|
|Venezuela||Present||Native||Holm et al., 1979|
|Croatia||Present||Introduced||Invasive||Silic and Solic, 1999|
|Czech Republic||Present||Introduced||Invasive||Sida, 2003|
|-Sicily||Present||Blando and Mineo, 2005|
|Romania||Present||Negrean and Ioana, 2012|
|Yugoslavia (former)||Present||Introduced||Invasive||Cronquist, 1976|
|-New South Wales||Present||Introduced||Invasive||Clements, 1983|
|New Zealand||Present||Introduced||Invasive||Michael, 1977|
History of Introduction and SpreadTop of page Michael (1977) records that it was already present in Europe in the early 1700s and was recorded in Australia in the 1840s. Little else is known about exact dates of introduction, although possible means were discussed by Sida (2003), who concludes that seed may have been introduced with cotton imports, with early infestations being recorded around textile factories.
Risk of IntroductionTop of page Although the risk of accidental introduction of C. bonariensis remains high, the fact that it is already so widespread means that the phytosanitary risk is relatively low. It is present in most regions where it is able to survive and grow, and exclusion from other areas where it is not yet present may be impossible. However, certain quarantine measures may ensure that it does not spread into certain specified areas within a country or region, such as protected areas. Being a weed of undisturbed ground, the potential risks to such sites may be considerable.
HabitatTop of page C. bonariensis occurs typically on waste land, around field edges, roadsides, in fallows and in orchards, in both tropical and subtropical regions, and to some extent in temperate zones. It generally prefers undisturbed habitats, and thus when occurring as a weed, is a problem in perennial crops.
Habitat ListTop of page
|Terrestrial – Managed||Cultivated / agricultural land||Present, no further details||Harmful (pest or invasive)|
|Managed forests, plantations and orchards||Present, no further details|
|Managed forests, plantations and orchards||Present, no further details||Harmful (pest or invasive)|
|Managed grasslands (grazing systems)||Present, no further details||Harmful (pest or invasive)|
|Disturbed areas||Present, no further details||Harmful (pest or invasive)|
|Rail / roadsides||Present, no further details||Harmful (pest or invasive)|
|Terrestrial ‑ Natural / Semi-natural||Natural forests||Present, no further details||Harmful (pest or invasive)|
Hosts/Species AffectedTop of page C. bonariensis is usually a weed of perennial crops, especially in orchards of both temperate and tropical fruit trees such as apple, olive, mango, etc., vineyards, plantation crops (date palm, tea), and also in pastures and in fallows (Perez and Duarte, 1991). It may, however, also occur in annual crops such as barley, wheat, maize, soyabean, sugar beet and oilseed rape, but in these cases is more prevalent in low-tillage or no-till farming practices.
Host Plants and Other Plants AffectedTop of page
|Beta vulgaris (beetroot)||Chenopodiaceae||Other|
|Glycine max (soyabean)||Fabaceae||Other|
|Helianthus annuus (sunflower)||Asteraceae||Main|
|Hordeum vulgare (barley)||Poaceae||Other|
|Malus domestica (apple)||Rosaceae||Main|
|Mangifera indica (mango)||Anacardiaceae||Main|
|Olea europaea subsp. europaea (European olive)||Oleaceae||Main|
|Phoenix dactylifera (date-palm)||Arecaceae||Main|
|Pyrus communis (European pear)||Rosaceae||Main|
|Triticum aestivum (wheat)||Poaceae||Other|
|Vitis vinifera (grapevine)||Vitaceae||Main|
|Zea mays (maize)||Poaceae||Other|
Biology and EcologyTop of page Genetics
C. bonariensis is a hexaploid, with a chromosome number (2n) of 54 (Thebaud and Abbott, 1995), the same as recorded for C. sumatrensis, with which it has been previously confused. The other common weedy species, C. canadensis, is by comparison, a diploid (2n=18). The role of ploidy in its evolution and spread is as yet unknown.
C. bonariensis is mainly an annual plant, germinating in autumn and persisting as a rosette of leaves over winter before shooting and flowering in the following spring. However, it may often behave as a biennial in temperate climates. It rarely, if ever, persists for a second season after flowering (unlike C. sumatrensis). Seeds need a temperature of 10-25°C, and require light for germination (Zinzolker et al., 1985). Establishment occurs mainly in relatively undisturbed situations, and cultivation in annual crops apparently buries most of the seed and greatly reduces emergence. After establishment as a rosette, elongation of the stem is inhibited by short days but occurs rapidly under longer day conditions (Zinzolker et al., 1985). Seed production can be as great as 226,000 seeds per plant in the USA (Kempen and Graf, 1981), and seed dispersal by wind is made highly efficient by the pappus.
Although occurring mainly in warm temperate climates, it has wide adaptation to hotter climates and can be found in many sub-tropical regions, and even tropical zones especially at higher altitudes. In Europe, it is found mainly in the Mediterranean region, though has recently been recorded further north. There is little evidence for preference regarding soil type. In Bhutan, it occurs at a wide range of altitudes, whereas C. floribunda is found mainly in lowlands, below 2000 m and C. canadensis tends to be restricted to higher altitudes, over 2000 m (Parker, 1992). C. bonariensis has been recorded at altitudes up to 3900 m in Bolivia (Missouri Botanical Garden, 2004).
A detailed study was undertaken by Prieur-Richard et al. (2002) of the invasion by C. bonariensis on Mediterranean annual plant communities. In agreement with earlier results suggesting that high nutrient availability can favour invasions, an abundant legume biomass in communities increased the final biomass and net fecundity of C. bonariensis, due to positive effects on soil nitrate concentration. Survival and establishment of C. bonariensis were mainly favoured by a high biomass of Asteraceae, and additional results from measurements of herbivory suggested that C. bonariensis survival was not related to abiotic conditions but may be due to protection against herbivores in plots with abundant Asteraceae. Establishment was on the other hand likely to be hindered by the effects of abundant grass and legume foliage on light quality, and therefore easier within an Asteraceae canopy. Prieur-Richard et al. (2002) concluded that invasion of Mediterranean old fields by species similar to C. bonariensis could be limited by favouring communities dominated by annual grasses.
Other studies looking at the invasion by C. bonariensis of fallows have observed that early high densities of the species are gradually replaced over several years by other plants, suggesting that C. bonariensis is a species of the early successional stage, having pioneering characteristics.
Soil TolerancesTop of page
Special soil tolerances
Natural enemiesTop of page
|Natural enemy||Type||Life stages||Specificity||References||Biological control in||Biological control on|
Means of Movement and DispersalTop of page Natural Dispersal (Non-Biotic)
C. bonariensis is principally a wind-dispersed species, facilitated by light seed accompanied by a pappus which aids flight (e.g. Andersen, 1992).
No information is available on the possibility of spread by animals, but if it occurs, it is likely to be only of minor significance in comparison to wind-dispersal.
Mowing along roadsides, especially during seed production, is likely to increase spread. Also, late tillage or other practices at such inappropriate times will also facilitate seed dispersal.
Seed of several Conyza species now widely present as weeds outside of their native ranges were probably introduced to most of their introduced ranges accidentally as contaminants in cotton, cereals or forage grains/seed. The first appearance of C. bonariensis around textile mills in Europe and elsewhere where exotic lead Sida (2003) to conclude that it may have been widely introduced from the New World as a contaminant of cotton.
Also a weed in nurseries, Conyza spp. may be spread as seed present in the soil in pots or other planting containers that accompany nursery stock, either as ornamentals or for establishing plantations. The spread of C. canadensis, along with numerous other weeds in central European forests, was thought to have been assisted by this method (see the datasheet on C. canadensis), and thus, presence in soil must be considered as a potential pathway.
Plant TradeTop of page
|Plant parts liable to carry the pest in trade/transport||Pest stages||Borne internally||Borne externally||Visibility of pest or symptoms|
|True seeds (inc. grain)||seeds||Yes||Pest or symptoms usually visible to the naked eye|
|Plant parts not known to carry the pest in trade/transport|
|Fruits (inc. pods)|
|Growing medium accompanying plants|
|Stems (above ground)/Shoots/Trunks/Branches|
Impact SummaryTop of page
|Fisheries / aquaculture||None|
ImpactTop of page C. bonariensis, though only recorded as a major weed in two countries, Argentina and Brazil (Holm et al., 1979), is frequently noted as a dominant weed, especially in orchards (for example, in olives in Spain and in apple in Pakistan) and pastures. Nevertheless, no single species competition studies have been conducted, and any crop loss data are inevitably confounded by the presence of other weed species. The widespread development of resistance to herbicides means, however, that it is tending to increase in importance. Economic impacts may also arise from the effects of C. bonariensis as a host for crop pests, as is common with other Conyzo species. C. bonariensis has been noted as an important host for various ant species, reported to be serious crop pests in China (Xie and Yao, 1989).
Environmental ImpactTop of page That C. bonariensis is principally a weed in undisturbed land, poses the risk that it may become invasive in protected areas.
Threatened SpeciesTop of page
|Threatened Species||Conservation Status||Where Threatened||Mechanism||References||Notes|
|Panicum fauriei (Carter's panicgrass)||NatureServe NatureServe; USA ESA listing as endangered species USA ESA listing as endangered species||Hawaii||Competition (unspecified)||US Fish and Wildlife Service, 2011|
|Scaevola coriacea (dwarf naupaka)||NatureServe NatureServe; USA ESA listing as endangered species USA ESA listing as endangered species||Hawaii||Competition (unspecified)||US Fish and Wildlife Service, 2010a|
|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, 2010b|
|Tetramolopium lepidotum (Waianae Range tetramolopium)||USA ESA listing as endangered species USA ESA listing as endangered species||Hawaii||Competition - strangling||US Fish and Wildlife Service, 2009|
Social ImpactTop of page Although social impacts are not recorded, the use of the common name 'asthmaweed' in the USA indicates the potential allergenic effects of C. bonariensis pollen on people.
Risk and Impact FactorsTop of page Invasiveness
- Proved invasive outside its native range
- Highly adaptable to different environments
- Highly mobile locally
- Has high reproductive potential
- Negatively impacts agriculture
- Competition - monopolizing resources
- Competition - strangling
- Pest and disease transmission
- Highly likely to be transported internationally accidentally
- Difficult to identify/detect as a commodity contaminant
- Difficult/costly to control
UsesTop of page C. bonariensis has only limited uses, though it is cultivated as a medicinal plant in some parts of the world, possibly for the noted antimicrobial effects (USDA-ARS, 2004). Plant extracts have been noted to have antifungal properties with possible uses against crop pathogens (e.g. Arora et al., 2003, Guatam et al., 2003).
Similarities to Other Species/ConditionsTop of page C. bonariensis is superficially similar to several other species occurring as weeds, of which the most widespread is C. canadensis, distinguished by finer, glabrous, yellow-green flower heads, 2-3 mm in diameter, with distinct white ray florets 0.5 to 1 mm long, and broader, greener, shallowly toothed leaves with distinct hairs on the margins (see the separate datasheet on C. canadensis). Two other species confused with C. bonariensis nomenclaturally are C. floribunda and C. sumatrensis. Both of these are somewhat more robust, about 1 m high or more, with seed heads slightly narrower than those of C. bonariensis, brownish grey pappus and much broader shallowly toothed leaves, often over 1 cm wide, without marginal hairs (see the datasheet on C. sumatrensis). The above differences are illustrated by Parker (1992), but for 'C. floribunda' read C. sumatrensis. For diagnostic keys differentiating Conyza bonariensis, C. canadensis and C. sumatrensis, see Reutelingsperger (2000), also Michael (1977) for the former two.
Prevention and ControlTop of page Cultural Control
C. bonariensis establishes from a small seed and the initial rosettes are readily destroyed by tillage. Once established, however, the plant becomes more difficult to control mechanically. Soil solarization is surprisingly ineffective (Silveira et al., 1988).
C. bonariensis is normally susceptible to a wide range of the standard herbicides for control of broad-leaved weeds, including 2,4-D, dicamba, atrazine, simazine, paraquat and glyphosate. However, it has developed resistance to paraquat and to triazines, and sometimes shows dual resistance to both. The mechanisms of resistance have been much studied and it has been shown that the resistance to paraquat is associated with a single dominant gene. The level of resistance is about 30-fold in the early vegetative stage before bolting but rises to 200- to 300-fold at flowering. The higher level of resistance is associated with increased levels of superoxide dismutase, ascorbate peroxidase and glutathione reductase at the flowering stage but not at the earlier stage (Amsellem et al., 1993; Ye and Gressel, 1994). There is still a lack of agreement on the exact mechanism(s) of resistance (Preston, 1994). The resistance to paraquat automatically confers increased tolerance of atrazine and acifluorfen as well as to sulfur dioxide (Shaaltiel et al., 1988), but not to the related herbicide morfamquat and only partially to diquat (Vaughn et al., 1989). Full resistance to triazines depends on a separate mechanism, the same as that in other weeds (Prado et al., 1989).
ReferencesTop of page
Adams CD, 1963. Compositae. In: Hutchinson J, Dalziel JM, Hepper FN, eds. Flora of West Tropical Africa, Volume 2, Second edition. London, UK: Crown Agents
Blando S, Mineo G, 2005. Tritrophic interrelations of two economically interesting ligaeid pests (Heteroptera). (Relazioni tritrofiche tra due Ligeidi (Heteroptera) di notevole interesse economico.) Bollettino di Zoologia Agraria e di Bachicoltura, 37(3):211-223
Cronquist A, 1976. Conyza Less. In: Tutin TG, Heywood VH, Burges NA, Moore DM, Valentine DH, Walters SM, Webb DA, eds. Flora Europaea, Volume 4, Plantaginaceae to Compositae (and Rubiaceae). Cambridge, UK: Cambridge University Press
Edgecombe WS, 1970. Weeds of Lebanon. Beirut, Lebanon: American University of Beirut
Finot SVL, Urbina PA, Minoletti OML, Wilckens ER, Figueroa RM, Riquelme CM, 1996. Achene and seedling morphology of Asteraceae weed species from south-central Chile. Agro-Ciencia, 12(1):15-29
Gautam K, Rao PB, Chauhan SVS, 2003. Antifungal potency of some species of family Asteraceae (Compositae) against Macrophomina phaseolina (Tassi) Goid. Journal of Mycology and Plant Pathology, 33(2):294-295
Hong SiSi, Miao ChongChong, Fang BenJi, Hu RenYong, Ding BingYang, 2008. On species diversity, niche breath and interspecies association in communities invaded by Spermacoce latifolia Zhejiang Province. Journal of Wuhan Botanical Research, 26(5):501-508. http://188.8.131.52/kp/yyzy/cscd/swu/cscd/wuhan/jianjie2.htm
Khalid S, 1995. Weeds of Pakistan. Compositae. Islamabad, Pakistan: Pakistan Agricultural Research Council
Kim HS, Ihm BS, Lee JS, Park SH, 2003. Ecological studies on the vegetation of abandoned salt field in Gasado. Korean Journal of Environment and Ecology, 17(2):123-132
Lind EM, Tallantire AC, 1971. Some Flowering Plants of Uganda. Nairobi, Kenya: Oxford University Press
Lorenzi H, 1982. Weeds of Brazil, terrestrial and aquatic, parasitic, poisonous and medicinal. (Plantas daninhas de Brasil, terrestres, aquaticas, parasitas, toxicas e medicinais.) Nova Odessa, Brazil: H. Lorenzi, 425 pp
Michael PW, 1977. Some weedy species of Amaranthus (amaranths) and Conyza/Erigeron (fleabanes) naturalized in the Asian-Pacific region. Proceedings of the 6th Asian-Pacific Weed Science Society Conference, Indonesia. Volume 1, 87-95
Missouri Botanical Garden, 2004. VAScular Tropicos database. Missouri Botanical Garden, Missouri, USA. http://mobot.mobot.org/W3T/Search/vast.html
Morgado-Arroyo F, Urzua-Soria FOT, 1995. Incidencia de enfermedades foliares y maleza en trigo (Triticum sativum L.) y cebada (Hordeum vulgare L.) en dos sistemas de labranza en el estado de Hidalgo. [Incidence of leaf diseases and weeds in wheat (Triticum sativum L.) and barley (Hordeum vulgare L.) under two tillage systems in the State of Hidalgo.] Revista Chapingo. Serie Proteccion Vegetal, 2(1):77-81
Morita H, 1997. Handbook of Arable Weeds of Japan. Tokyo, Japan: Kumiai Chemical Industry Co. Ltd., 128 pp
Negrean G, Ioana C, 2012. Conyza bonariensis, a new plant with invasive character in Romanian flora. Analele Universitatcedilla~ii din Craiova - Biologie, Horticultura, Tehnologia Prelucrarii Produselor Agricole, Ingineria Mediului, 17:743-748. http://anucraiova.3x.ro/
Prado Rde, Dominguez C, Tena M, 1989. Characterization of triazine-resistant biotypes of common lambsquarters (Chenopodium album), hairy fleabane (Conyza bonaeriensis), and yellow foxtail (Setaria glauca) found in Spain. Weed Science, 37(1):1-4; 17 ref
Preston C, 1994. Resistance to photosystem 1 disrupting herbicides. In: Powles SB, Holtum JAM, eds. Herbicide Resistance in Plants: Biology and Biochemistry. Roca Baton, USA: Lewis Publications, 61-82
Prieur-Richard AH, Lavorel S, Santos Ados, Grigulis K, 2002. Mechanisms of resistance of Mediterranean annual communities to invasion by Conyza bonariensis: effects of native functional composition. Oikos, 99(2):338-346; 37 ref
Royal Botanic Garden Edinburgh, 2004. Flora Europaea Database. Royal Botanic Garden Edinburgh, UK. http://rbg-web2.rbge.org.uk/FE/fe.html
Shaaltiel Y, Glazer A, Bocion PF, Gressel J, 1988. Cross tolerance to herbicidal and environmental oxidants of plant biotypes tolerant to paraquat, sulfur dioxide, and ozone. Pesticide Biochemistry and Physiology, 31(1):13-23
Sida O, 2003. Conyza triloba, new to Europe, and Conyza bonariensis, new to the Czech Republic. Preslia, 75(3):249-254
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