Conyza bonariensis
(hairy fleabane)

Pictures

Top of page

Identity

Top 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

EPPO code

• ERIBO (Erigeron bonariensis)

Summary of Invasiveness

Top 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 Tree

Top 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 Nomenclature

Top 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.

Description

Top 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 Type

Top of page Annual
Biennial
Broadleaved
Herbaceous
Seed propagated

Distribution

Top 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 Table

Top 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.

History of Introduction and Spread

Top 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 Introduction

Top 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.

Habitat

Top 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 List

Top of page

Category	Sub-Category	Habitat	Presence	Status
Terrestrial
	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 Affected

Top 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 Affected

Top of page

Biology and Ecology

Top 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.

Reproductive Biology

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.

Environmental Requirements

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).

Associations

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 Tolerances

Top of page

Soil drainage

• free
• impeded

Soil reaction

• acid
• neutral

Soil texture

• heavy
• light
• medium

Special soil tolerances

• infertile
• saline
• shallow
• sodic

Natural enemies

Top of page

Means of Movement and Dispersal

Top 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).

Vector Transmission.

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.

Agricultural Practices

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.

Accidental Introduction

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.

Pathway Vectors

Top of page

Plant Trade

Top of page

Plant parts not known to carry the pest in trade/transport
Bark
Bulbs/Tubers/Corms/Rhizomes
Flowers/Inflorescences/Cones/Calyx
Fruits (inc. pods)
Growing medium accompanying plants
Leaves
Roots
Seedlings/Micropropagated plants
Stems (above ground)/Shoots/Trunks/Branches

Impact Summary

Top of page

Impact

Top 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 Impact

Top of page That C. bonariensis is principally a weed in undisturbed land, poses the risk that it may become invasive in protected areas.

Threatened Species

Top of page

Social Impact

Top 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 Factors

Top of page Invasiveness

• Proved invasive outside its native range
• Highly adaptable to different environments
• Highly mobile locally
• Has high reproductive potential

Impact outcomes

• Negatively impacts agriculture

Impact mechanisms

• Competition - monopolizing resources
• Competition - strangling
• Competition
• Pest and disease transmission

Likelihood of entry/control

• Highly likely to be transported internationally accidentally
• Difficult to identify/detect as a commodity contaminant
• Difficult/costly to control

Uses

Top 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/Conditions

Top 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 Control

Top 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).

Chemical Control

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).

References

Top 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

Amit Chauhan, Singh DK, 2005. Interesting plant records from Ladakh (Jammu & Kashmir). Indian Journal of Forestry, 28(1):71-74

Amsellem Z, Jansen MAK, Driesenaar ARJ, Gressel J, 1993. Developmental variability of photooxidative stress tolerance in paraquat-resistant Conyza. Plant Physiology, 103(4):1097-1106

Andersen MC, 1992. An analysis of variability in seed settling velocities of several wind-dispersed Asteraceae. American Journal of Botany, 79(10):1087-1091

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

Charu Arora, Kaushik RD, 2003. Fungicidal activity of plants extracts from Uttaranchal hills against soybean fungal pathogens. Allelopathy Journal, 11(2):217-228; 24 ref

Chaudhary SA, Parker C, Kasasian L, 1981. Weeds of Central, Southern and Eastern Arabian Peninsula. Tropical Pest Management, 27(2):181-190

Clements A, 1983. Suburban development and resultant changes in the vegetation of the bushland of the northern Sydney region. Australian Journal of Ecology, 8(3):307-319

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

Fatehi J, Hedjaroude GA, Ershad D, 1993. Studies on Septoria species in Iran-I. Iranian Journal of Plant Pathology, 29(1-2):25-28 (En), 53-75 (Pe)

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

Holm LG, Pancho JV, Herberger JP, Plucknett DL, 1979. A geographical atlas of world weeds. New York, USA: John Wiley and Sons, 391 pp

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://202.127.158.171/kp/yyzy/cscd/swu/cscd/wuhan/jianjie2.htm

Kempen HM, Graf J, 1981. Weed seed production. Proceedings of the Western Society of Weed Science, Volume 34:78-81

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

Lanfranco E, 1976. Report on the present situation of the Maltese flora. Maltese Naturalist, 2:69-80

Lind EM, Tallantire AC, 1971. Some Flowering Plants of Uganda. Nairobi, Kenya: Oxford University Press

Liu QuanRu, Kang MuYi, 2008. Some newly recorded vascular plants from Shanxi. Acta Botanica Boreali-Occidentalia Sinica, 28(2):412-415. http://xbzwxb.nwsuaf.edu.cn

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/

Parker C, 1992. Weeds of Bhutan. Weeds of Bhutan., vi + 236 pp

Perez M, Duarte G, 1991. Weed control in leys. Revista de los CREA, No. 146:58-64

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

Reutelingsperger LFPM, 2000. Conyza sumatrensis: starting to spread into the Netherlands?. Gorteria, 26(5):224-226; 13 ref

Royal Botanic Garden Edinburgh, 2004. Flora Europaea Database. Royal Botanic Garden Edinburgh, UK. http://rbg-web2.rbge.org.uk/FE/fe.html

Satya Narain, Kanchan Lata, 2004. Taxonomical account of family Asteraceae in Bundelkhand Region (U.P.). Journal of Economic and Taxonomic Botany, 28(2):274-291

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

Silic C, Solic ME, 1999. Contribution to the knowledge of the neophytic flora in the Biokovo area (Dalmatia, Croatia). Natura Croatica, 8(2):109-116

Silveira HL, Caixinhas ML, Leitao A, Gomes R, 1988. Evolution of actual and potential weed flora after soil solarisation. VIIIe Colloque International sur la Biologie, l'Ecologie et la Systematique des Mauvaises Herbes, Paris, France: A.N.P.P., Vol. 1:59-69

Siverio A, Sobrino E, Rodríguez H, Arévalo JR, 2011. Weeds of golf courses on the island of Tenerife. (Malas hierbas de los campos de golf de la isla de Tenerife.) In: Plantas invasoras resistencias a herbicidas y detección de malas hierbas. XIII Congreso de la Sociedad Española de Malherbología, La Laguna, Spain, 22-24 November 2011 [ed. by Arévalo JR, Fernández S, López F, Recasens J, Sobrino E]. Madrid, Spain: Sociedad Española de Malherbología (Spanish Weed Science Society), 83-86

Stroud A, Parker C, 1989. A Weed Identification Guide for Ethiopia. Rome, Italy: Food and Agriculture Organization

Thebaud C, Abbott RJ, 1995. Characterization of invasive Conyza species (Asteraceae) in Europe: quantitative trait and isozyme analysis. American Journal of Botany, 82(3):360-368

US Fish and Wildlife Service, 2009. Tetramolopium lepidotum ssp. lepidotum (no common name). 5-Year Review: Summary and Evaluation. In: Tetramolopium lepidotum ssp. lepidotum (no common name). 5-Year Review: Summary and Evaluation : US Fish and Wildlife Service.13 pp.

US Fish and Wildlife Service, 2010. Scaevola coriacea (dwarf naupaka). 5-Year Review: Summary and Evaluation. In: Scaevola coriacea (dwarf naupaka). 5-Year Review: Summary and Evaluation : US Fish and Wildlife Service.19 pp.

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.

US Fish and Wildlife Service, 2011. Panicum fauriei var. carteri (no common name). 5-Year Review: Summary and Evaluation. In: Panicum fauriei var. carteri (no common name). 5-Year Review: Summary and Evaluation : US Fish and Wildlife Service.17 pp.

USDA-ARS, 2004. Germplasm Resources Information Network (GRIN). Online Database. Beltsville, Maryland, USA: National Germplasm Resources Laboratory. https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearch.aspx

USDA-NRCS, 2004. The PLANTS Database, Version 3.5. Baton Rouge, USA: National Plant Data Center. http://plants.usda.gov

Vaughn KC, Vaughan MA, Camilleri P, 1989. Lack of cross-resistance of paraquat-resistant hairy fleabane (Conyza bonariensis) to other toxic oxygen generators indicates enzymatic protection is not the resistance mechanism. Weed Science, 37(1):5-11

Victor R, Ilango J, Pagalavan B, Ramasubramanian B, 2001. Evaluation of napropamide for control of weeds in tea (Camellia spp. L.). Indian Journal of Weed Science, 33(3/4):227-228

Wang Yong, Song GuoYuan, Cao Tong, Guo ShuiLiang, 2007. Determination on niche of early spring weeds in Shanghai suburb. Journal of Shanghai Jiaotong University - Agricultural Science, 25(1):38-44

Wells MJ, Balsinhas AA, Joffe H, Engelbrecht VM, Harding G, Stirton CH, 1986. A catalogue of problem plants in South Africa. Memoirs of the botanical survey of South Africa No 53. Pretoria, South Africa: Botanical Research Institute

Wu HaiRong, Qiang Sheng, 2003. Quantitative survey on exotic weeds in autumn in Nanjing. Biodiversity Science, 11(5):432-438. [Special issue: Commemoration of the 10th anniversary of Biodiversity Science.] http://www.biodiversity-science.net

Xie FY, Yao LX, 1989. A study on Dorylus orientalis Westwood. Insect Knowledge, 26(5):291-293

Ye B, Gressel J, 1994. Constitutive variation of ascorbate peroxidase activity during development parallels that of superoxide dismutase and glutathione reductase in paraquat-resistant Conyza. Plant Science (Limerick), 102(2):147-151

Zinzolker A, Kigel J, Rubin B, 1985. Effects of environmental factors on the germination and flowering of Conyza albida, C. bonariensis and C. canadensis. Phytoparasitica, 13(3/4):229-230

Distribution Maps

Top of page