Baccharis pilularis (coyote brush)
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- History of Introduction and Spread
- Risk of Introduction
- Habitat List
- Biology and Ecology
- Latitude/Altitude Ranges
- Natural enemies
- Notes on Natural Enemies
- Means of Movement and Dispersal
- Impact Summary
- Impact: Economic
- Impact: Environmental
- Risk and Impact Factors
- Similarities to Other Species/Conditions
- Prevention and Control
- Gaps in Knowledge/Research Needs
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Baccharis pilularis DC.
Preferred Common Name
- coyote brush
Local Common Names
- USA: chaparral broom; coyote bush; coyotebrush; Dwarf Baccharis; dwarf chaparral false willow; dwarf coyote bush; kidney-wort baccharis
- BACPI (Baccharis pilularis)
Summary of InvasivenessTop of page
B.pilularis, commonly known as coyote brush, is an evergreen shrub native to Pacific coastal North America, Oregon and California in the USA, and northern Baja California in Mexico. There is little information to indicate the weediness of this species and very few reports of its establishment outside its native range, though the horticultural forms may be found elsewhere and it can be found in various botanic gardens around the world. B. pilularis is a pioneer species and can become abundant and dense in its native habitat where land is cleared or overgrazed. However, these situations can be prevented by good land management practices. Some sources refer to the erect form being invasive in areas of exposed soil, such as caused by overgrazing, changing fire regimes or clearing, but these are generally older sources (Leonard, 1957; McBride and Heady, 1968).
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Spermatophyta
- Subphylum: Angiospermae
- Class: Dicotyledonae
- Order: Asterales
- Family: Asteraceae
- Genus: Baccharis
- Species: Baccharis pilularis
Notes on Taxonomy and NomenclatureTop of page
Baccharis is a very large genus of 400-500 species, mostly from South America (Budel et al., 2008). It has been divided into several sections. Baccharis pilularis DC. has been placed in section Baccharis and as such, its closest relatives include B. halimifolia L., B. neglecta Britt., B. emoryi Gray [B. salicina], B. dioica Vahl and B. conferta Kunth (Nesom, 1990).
Two subspecies are recognized (Flora of North America Editorial Committee, 2015; The Plant List, 2013). The nominate subspecies, pilularis, is a prostrate plant found naturally along coastal bluffs and beaches in California. This subspecies has been bred by horticulturists to produce several varieties sold as ground cover (Pittenger et al., 2001). The second subspecies, consanguinea (DC.) C.B.Wolf is an erect plant and is a dominant member of the coastal sage scrub (Crutsinger et al., 2014) along the west coast of the USA and northern Mexico.
DescriptionTop of page
B. pilularis is an evergreen shrub, often 1-3 m in height (Steinberg, 2002); leaves are sessile or short petiolate with blades oblanceolate to obovate with three principal veins and in alternate leaf arrangement (Flora of North America Editorial Committee, 2015). There is a well-developed taproot of up to 3 m and lateral roots are also well developed (Steinberg, 2002). Inflorescences in paniculiform arrays (Flora of North America Editorial Committee, 2015) and made up of small whitish (female) to yellowish (male) flowers. Female flowers are discoid without ray florets (Steinberg, 2002). They are 0.4-0.63 cm long, and clustered at branch tips or in leaf axils. Male flowers are slightly smaller. Achenes are 0.1-0.2 cm long with a 0.6-1 cm long pappus (Munz, 1973; Hickman, 1993). Plants are dioecious with male plants flowering before the females. Achenes are small with long pappus. Seeds are very light (Steinberg, 2002).
Baccharis pilularis subsp. pilularis is a prostrate form with flexible stems and often forms mats (Flora of North America Editorial Committee, 2014). Baccharispilularis subsp. consanguinea is an erect bush typically 3-4 m in height.
DistributionTop of page
B. pilularis mostly occurs within its native or endemic range which is the coastal areas of Oregon, California and northern Baja California. There have been some plant specimens collected in Arizona and New Mexico; the specimen reported from New Mexico was regarded as a waif or weedy introduction (Flora of North America Editorial Committee, 2015; USDA-NRCS, 2015). Elsewhere there may be specimens in botanic gardens and the horticultural varieties used for ground cover may also have a wider distribution within the USA.
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||Planted||Reference||Notes|
|Mexico||Present||Native||Not invasive||Flora of North America Editorial Committee, 2015||Present in Baja California|
|-California||Widespread||Native||Not invasive||Flora of North America Editorial Committee, 2015; USDA-NRCS, 2015|
|-New Mexico||Present, few occurrences||Native||Not invasive||Flora of North America Editorial Committee, 2015; USDA-NRCS, 2015|
|-Oregon||Widespread||Native||Not invasive||Natural||Flora of North America Editorial Committee, 2015; USDA-NRCS, 2015|
|Australia||Present||Present based on regional distribution.|
|-Victoria||Present only in captivity/cultivation||Introduced||Not invasive||Royal Botanic Gardens Victoria, 2015||2 plants in Garden|
History of Introduction and SpreadTop of page
There is no published literature to indicate that B. pilularis has established or spread anywhere outside its native range.
Risk of IntroductionTop of page
Given that B. pilularis is not known to have established or spread outside its native range and that present day requirements for national and international movements are much more stringent than in past years, the risk of introduction could be considered low. However one closely related congener, Baccharis halimifolia, has become a serious invasive weed in Australia, France, Spain, Russia and elsewhere in Europe (Palmer and Sims-Chilton, 2012; EPPO, 2013). It is thought that B. halimifolia was brought to Australia in the nineteenth century as an ornamental shrub for Brisbane gardens (Bailey, 1900; McFadyen, 1973). It was similarly introduced into Europe (Fournier, 1936).
HabitatTop of page
B. pilularis is typically found in wooded or scrubby habitat and along coastal hillsides and canyons below 600 m (2000 ft) (Lady Bird Johnson Wildflower Centre, 2015). Baccharis pilularis subsp. pilularis is primarily found on sandy coastal bluffs and beaches in California (Flora of North America Editorial Committee, 2015) where it plays a role in soil binding. The erect subsp. consanguinea, is a dominant shrub in coastal sage scrub communities (Steinberg, 2002; Flora of North America Editorial Committee, 2015).
Habitat ListTop of page
|Terrestrial – Managed||Managed grasslands (grazing systems)||Present, no further details||Harmful (pest or invasive)|
|Managed grasslands (grazing systems)||Present, no further details||Natural|
|Disturbed areas||Principal habitat||Natural|
|Rail / roadsides||Present, no further details||Natural|
|Urban / peri-urban areas||Present, no further details||Natural|
|Urban / peri-urban areas||Present, no further details||Productive/non-natural|
|Terrestrial ‑ Natural / Semi-natural||Natural forests||Present, no further details||Natural|
|Natural grasslands||Present, no further details||Natural|
|Riverbanks||Present, no further details||Natural|
|Coastal areas||Principal habitat||Natural|
|Coastal dunes||Principal habitat||Natural|
Biology and EcologyTop of page
B. pilularis has a chromosome number of n=9 (Raven et al., 1960; DeJong and Montgomery, 1963; Keil and Pinkava, 1976) which is also the most common number reported for other congeners though tetraploid and aneuploid species have been reported from Peru.
The autecology of the congener, B. halimifolia, has been described (Westman et al., 1975) and this study could be used as an indicator for B. pilularis. B. pilularis is a dioecious species that flowers in autumn. Wind is the main pollination mechanism and female plants produce prolific quantities of seeds. The achenes are attached to a pappus and are wind dispersed. Seeds are not long lived and it would be unlikely that a viable seed store would build up from year to year in the field. Seeds may have a facultative light requirement for germination.
Physiology and Phenology
The phenology of the erect form has been described in detail by Hobbs and Mooney (1986).
Plants live 10-20 years but basal sprouting and layering may extend this lifespan (Steinberg, 2002).
ClimateTop of page
|BS - Steppe climate||Preferred||> 430mm and < 860mm annual precipitation|
|BW - Desert climate||Tolerated||< 430mm annual precipitation|
|Cf - Warm temperate climate, wet all year||Tolerated||Warm average temp. > 10°C, Cold average temp. > 0°C, wet all year|
Latitude/Altitude RangesTop of page
|Latitude North (°N)||Latitude South (°S)||Altitude Lower (m)||Altitude Upper (m)|
RainfallTop of page
|Parameter||Lower limit||Upper limit||Description|
|Mean annual rainfall||250||750||mm; lower/upper limits|
Natural enemiesTop of page
|Natural enemy||Type||Life stages||Specificity||References||Biological control in||Biological control on|
|Hellinsia grandis||Herbivore||Stems||to genus|
|Prochoerodes truxaliata||Herbivore||Leaves||to genus|
|Puccinia evadens||Pathogen||Stems||to genus|
|Rhopalomyia californica||Herbivore||Whole plant||to genus|
|Trirhabda flavolimbata||Herbivore||Leaves||to genus|
Notes on Natural EnemiesTop of page
A large arthropod fauna is associated with B. pilularis (Tilden, 1951). Several species have been shown to be host specific including the cecidomyid fly Rhopalomyia californica and pathogen Puccinia evadens (Palmer, 1986; Palmer and Tilden, 1988; Ehler et al., 1990; Palmer et al., 1993).
Means of Movement and DispersalTop of page
B. pilularis produces prolific quantities of seeds which are wind borne on their pappus. The plant is an early colonizer of cleared areas.
The horticultural varieties used for urban ground cover are sold through commercial nurseries but these are mainly derived from male plants and therefore unlikely to establish in natural habitats.
Impact SummaryTop of page
Impact: EconomicTop of page
B. pilularis, which is found primarily in its native habitat, causes little economic impact. Being a pioneer species, it will become more abundant and dense where land is cleared or overgrazed. These situations can be prevented by good land management practices while physical and chemical techniques are available to reclaim affected land.
Impact: EnvironmentalTop of page
Impact on Habitats
B. pilularis, which is found primarily in its native habitat, is a pioneer species and can become abundant and dense where land is cleared or overgrazed. These situations can be prevented by good land management practices.
Impact on Biodiversity
Little information is available to indicate the weediness of B. pilularis. However, it may indirectly affect an endangered butterfly species (Lange’s metalmark butterfly, (Apodemia mormo langei)) in the Antioch Dunes National Wildlife Refuge in the San Francisco Bay-Delta area. Plantings of the host plant (Eriogonum nudum var. auriculum) of this butterfly are assisted by the removal of B. pilularis from the restoration areas (US Fish and Wildlife Service, 2008). Two other endangered species, the Antioch Dunes evening-primrose, (Oenothera deltoides subsp. howellii) and the Contra Costa wallflower (Erysimum capitatum var. angustatum) may also be affected by the presence of B. pilularis (US Fish and Wildlife Service, 2008).
Risk and Impact FactorsTop of page Invasiveness
- Abundant in its native range
- Pioneering in disturbed areas
- Fast growing
- Has high reproductive potential
- Reproduces asexually
- Damaged ecosystem services
- Ecosystem change/ habitat alteration
- Competition - shading
UsesTop of page
The cultivars of the prostrate subspecies are popular ground cover plants and are widely sold through retail nurseries. The erect form has no agricultural use.
Both subspecies are important components of their respective ecosystems and thereby provide both social benefits and environmental services.
Similarities to Other Species/ConditionsTop of page
The erect form is not dissimilar to other Baccharis species, such as B. sarothroides (found in Arizona and New Mexico), B. neglecta (Texas), B. halimifolia (Gulf Coast and Eastern seaboard of the USA) and B. conferta (Mexico).B. emoryi is also found in some of its range and can be difficult to distinguish from B.pilularis subsp. consanguinea because identifiable characters such as plant height, leaf length, length of pappus and bract shape have overlapping values (Chester and Newell, 2006). Within its natural range along the western coast of the USA, it is unlikely to be misidentified for non-Baccharis plants as its morphology, evergreen nature, alternate leaf arrangement and dioecious habit make it quite distinctive.
Prevention and ControlTop of page
Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.
Prevention and Control
B. pilularis is largely confined to its native range where it is generally not regarded as weedy. As there is little history indicating that it is a significant disperser or invader, specific measures to prevent dispersal or movement do not seem warranted. However, plants should not be moved to new areas without due assessment.
Within its native range, there are control techniques available should encroachment on grasslands be considered undesirable. Burning and controlled grazing have been suggested (McBride and Heady, 1968). Herbivory by small mammals in closed shrub stands may also be important in reducing the abundance of herbaceous species following shrub invasion in grassland (Hobbs and Mooney, 1986). Herbicides such as glyphosate are also available (Gambril, 1983; Mortenson, 1984).
Biological control could not be considered within North America because B. pilularis is a native, endemic species. However should B. pilularis ever become a serious weed over large scale areas on another continent then a suite of effective agents would be available for consideration. The most obvious choice would be the cecidomyid fly Rhopalomyia californica, which has been demonstrated to give significant control of B. pilularis in its native range (Ehler et al., 1984; Ehler, 1987) and also spectacular control of Baccharis halimifolia in Australia (McFadyen, 1985). A second potential agent is the rust Puccinia evadens. Both B. pilularis and B. halimifolia are hosts of this pathogen which has also contributed to the successful control of B. halimifolia in Australia. Other insect species found on B. pilularis would also be sufficiently host specific and laboratory evidence suggests that most of the 14 agents released in Australia for B. halimifolia (Palmer and Sims-Chilton, 2012; Winston et al., 2014) might also establish on B. pilularis.
Gaps in Knowledge/Research NeedsTop of page
Further research of the biology, autecology, and phenology of B. pilularis are needed.
ReferencesTop of page
Bailey FM, 1900. The Queensland Flora, Part 3. Brisbane, Australia: Queensland Government, 279 pp.
Budel JM; Matzenbacher NI; Duarte MR, 2008. Genus Baccharis (Asteraceae): a review of chemical and pharmacological studies. In: Phytopharmacology and therapeutic values III [ed. by Singh, V. K.\Govil, J. N.]. Houston, USA: Studium Press LLC, 1-18.
Chester T; Newell R, 2006. Plants of Southern California: Baccharis emoryi/B. pilularis at Upper Newport Bay. California, USA: Chester T, Newell R. http://tchester.org/plants/analysis/baccharis/emoryi_pilularis.html
Crutsinger GM; Rodriguez-Cabal MA; Roddy AB; Peay KG; Bastow JL; Kidder AG; Dawson TE; Fine PVA; Rudgers JA, 2014. Genetic variation within a dominant shrub structures green and brown community assemblages. Ecology, 95(2):387-398. http://www.esajournals.org/doi/full/10.1890/13-0316.1
DeJong D; Montgomery F, 1963. Chromosome numbers in some Californian Compositae-Astereae, 5(3):255-256.
Ehler LE; Endicott PC; Hertlein MB; Alvarado-Rodriquez B, 1984. Medfly eradication in California: impact of malathion-bait sprays on an endemic gall midge and its parasitoids. Entomologia Experimentalis et Applicata, 36(3):201-208.
Ehler LE; Kinsey MG; Palmer WA, 1990. Further observations on the biology and host specificity of Prochoerodes truxaliata (Guenée) (Lepidoptera: Geometridae), a biological-control agent for Baccharis halimifolia L. in Australia. Pan-Pacific Entomologist, 66(1):79-88.
EPPO, 2013. Pest risk analysis for Baccharis halimifolia. Paris, France: European and Mediterranean Plant Protection Organization. http://www.eppo.int/QUARANTINE/Pest_Risk_Analysis/PRA_intro.htm
Flora of North America Editorial Committee, 2015. Flora of North America North of Mexico. St. Louis, Missouri and Cambridge, Massachusetts, USA: Missouri Botanical Garden and Harvard University Herbaria. http://www.efloras.org/flora_page.aspx?flora_id=1
Fournier P, 1936. Les Quatre flore de France. Paris, France: Dunod, 1103 pp.
Gambril R, 1983. Control of coyote brush using Roundup in combination with different surfactants and penetrants. ([Poster].) In: Proceedings, 35th Annual California Weed Conference. El Macero, California, USA: California Weed Conference Office, 129-141.
Keil D; Pinkava D, 1976. Chromosome count and taxonomic notes for Compositae from the United States and Mexico. Am J Bot, 63:1393-1403.
McBride J; Heady HF, 1968. Invasion of grassland by Baccharis pilularis D.C. Journal of Range Management, 21(2):106-108.
McFadyen PJ, 1973. Insects for biological control. Qld Agric J, 99(11):607-611.
McFadyen PJ, 1985. Introduction of the gall fly Rhopalomyia californica from the U.S.A. into Australia for the control of the weed Baccharis halimifolia. Proceedings of the VI International Symposium on Biological Control of Weeds Ottawa, Canada; Agriculture Canada, 779-787
Munz PA, 1973. A California flora and supplement. Berkeley, California, USA: University of California Press, 1905 pp.
Nesom GL, 1990. Infrageneric taxonomy of North and Central American Baccharis (Asteraceae: Astereae). Phytologia, 68(6):40-46.
Palmer WA, 1986. The host range of Trirhabda flavolimbata (Mannerheim) and its suitability as a biocontrol agent for Baccharis spp. (Asteraceae: Astereae). Coleopts Bull, 40:149-153.
Palmer WA; Diatloff G; Melksham J, 1993. The host specificity of Rhopalomyia californica Felt (Diptera: Cecidomyiidae) and its importation into Australia as a biological control agent for Baccharis halimifolia L. Proceedings of the Entomological Society of Washington, 95(1):1-6
Palmer WA; Sims-Chilton NM, 2012. Baccharis halimifolia L. - groundsel bush. In: Biological Control of Weeds in Australia [ed. by Julien, M. \McFadyen, R. \Cullen, J.]. Melbourne, Australia: CSIRO Publishing.
Palmer WA; Tilden JW, 1988. Host specificity and biology of Prochoerodes truxaliata (Guenee) (Geometridae), a potential biocontrol agent for the rangeland weed Baccharis halimifolia L. in Australia. J Lepid Soc, 41:199-208.
Royal Botanic Gardens Victoria, 2015. Royal Botanic Gardens Victoria. Victoria, Australia: Royal Botanic Gardens Victoria. http://www.rbg.vic.gov.au/
Steinberg PD, 2002. Baccharis pilularis. Fire Effects Information System. Washington DC, USA: US Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. http://www.feis-crs.org/
The Plant List, 2013. The Plant List: a working list of all plant species. Version 1.1. London, UK: Royal Botanic Gardens, Kew. http://www.theplantlist.org
Tilden JW, 1951. The insects associates of Baccharis pilularis De Candolle. Microentomology, 16:149-188.
US Fish and Wildlife Service, 2008. Five year review and evaluation of Lange's metalmark butterfly, (Apodemia mormo langei), the Antioch Dunes evening-primrose, (Oenothera deltoides subsp. howellii) and the Contra Costa wallflower (Erysimum capitatum var. angustatum). Sacramento, USA: Sacramento Fish and Wildlife Field Office, US Fish and Wildlife Service, 31 pp.
USDA-NRCS, 2015. The PLANTS Database. Baton Rouge, USA: National Plant Data Center. http://plants.usda.gov/
Westman WE; Panetta FD; Stanley TD, 1975. Ecological studies on reproduction and establishment of the woody weed, groundsel bush (Baccharis halimifolia L.: Asteraceae). Australian Journal of Agricultural Research, 26:855-70.
Winston RL; Schwarzländer M; Hinz HL; Day MD; Cock MJW; Julien MH, 2014. Biological control of weeds: a world catalogue of agents and their target weeds, Ed.5 [ed. by Winston, R. L.\Schwarzländer, M\Hinz, H. L.\Day, M. D.\Cock, M. J. W.\Julien, M. H.]. Morgantown, USA: USDA Forest Service, Forest Health Technology Enterprise Team, 838 pp. http://www.ibiocontrol.org/catalog/JulienCatalogueFHTET_2014_04.pdf
ContributorsTop of page
20/08/15 Original text by:
Bill Palmer, Biosecurity Queensland, Brisbane, Queensland, Australia
Distribution MapsTop of page
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