- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Plant Type
- Distribution Table
- History of Introduction and Spread
- Habitat List
- Latitude/Altitude Ranges
- Air Temperature
- Rainfall Regime
- Soil Tolerances
- Notes on Natural Enemies
- Means of Movement and Dispersal
- Pathway Causes
- Pathway Vectors
- Impact Summary
- Economic Impact
- Environmental Impact
- Threatened Species
- Social Impact
- Risk and Impact Factors
- Detection and Inspection
- 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
- Soliva sessilis Ruiz & Pav., 1794
Other Scientific Names
- Soliva daucifolia Nutt., 1841
- Solivia pterosperma (Juss.) Less., 1832
International Common Names
- English: field burrweed; field soliva
Local Common Names
- Australia: bindyi; jo jo; lawn burweed
- Canada: carpet burweed
- New Zealand: Onehunga weed
Summary of InvasivenessTop of page
S. sessilis spreads readily in areas of worn, poor quality turf. The seeds can cling to fabric such as tent floors and be transported long distances. In local areas, it may be moved on the soles of shoes, particularly soft-soled shoes commonly worn around the beach and when camping. It was first found in California in 1836, probably coming in with shipments of hides from South America (Ray, 1987). Once established, the plant forms dense carpets that suppress most other lawn species and can out-compete rare species (Castro, 2006). It is considered one of the most hated turf weeds in New Zealand because it can make barefoot walking very painful (Harrington, 2009). It is low-growing and escapes the blades of most mowers. It has developed a resistance to synthetic auxin herbicides of the carboxylic acid family (Castro, 2006). A carpet burweed (S. sessilis) weed alert is listed by the British Columbia Ministry of Agriculture and Lands, Canada (Anon., 2009).
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Spermatophyta
- Subphylum: Angiospermae
- Class: Dicotyledonae
- Order: Asterales
- Family: Asteraceae
- Genus: Soliva
- Species: Soliva sessilis
Notes on Taxonomy and NomenclatureTop of page
This plant was first described from Chile in 1794. The genus was named after Dr. Salvador Soliva, an eighteenth century physician to the Spanish Court. The common name, Onehunga weed is thought to come from the port suburb of Auckland, New Zealand where this plant was first found. The name, burweed comes from the sharp spines on the achenes that remain upright in the dried head of the flower (Ray, 1987; WSWCB, 2007; CalFlora, 2009).
DescriptionTop of page
S. sessilis is a low-growing winter annual that germinates during the wet period in Mediterranean climate areas and grows throughout the winter when the weather is warm enough. It may also germinate in the spring and flower later that same spring, acting like an annual. In British Columbia, Canada, flowering occurs from March to July (Castro, 2006). Following flowering, the plants wither and dry up, leaving the sharply pointed seeds sitting upright in the head where they can easily attach to any passing shoe or to tent floors.
The flowers of S. sessilis are small and inconspicuous. They are found in the axils of the leaves or in the branches of the stem. S. sessilis appears to continue to grow as long as conditions are favourable, with new stem branches and leaves and thus flowers appearing. This growth pattern can provide flowers at various stages of growth and development on a single plant. The heads consist of female florets lacking a corolla around the outside with functionally male florets with much reduced four-toothed whitish to pale-green translucent corollas on the inside (Castro, 2006). The involucre consists of seven to eight greenish bracts (Castro, 2006).
Fruit and Seeds
The seeds of S. sessilis are sharply pointed, flattened achenes with wings and/or barbs of various shapes (Ray, 1987). The seeds may also have stiff hairs that assist in attaching the seed to the hair of passing animals. The shape of the wings can vary substantially and appear to be indicative of different races of the species (Harrington, 2009). Seeds are borne in heads (composite flowers) that arise in the axils of leaves and stem branches. Single plants may have many (1 to 10 or more) seed heads with 5 to 10 seeds per head (Castro, 2006). Most plants in British Columbia, Canada produce 100 or more seeds. Seed weights range from 0.48g/1000 seeds to 0.94g/1000 seeds (Castro, 2006). Seeds range in length from 3.5 to 5.2 mm (Castro, 2006).
Germination and Growth
Germination of S. sessilis is epigeal with the first leaves forming above the cotyledons, being oblong lanceolate. Dissected leaves follow and a basal rosette of petioled dissected leaves forms. A single flower head forms in this rosette, and if conditions are poor, usually drying out is the primary cause of cessation of growth; this flower head is the only one formed. However, in most cases, growth continues with secondary stems and additional leaves forming from the main stem with additional flower heads forming in the axils of new leaves and the secondary stems. The roots of S. sessilis are fibrous and not very extensive. Plants can be easily plucked from moist soil as the rosette provides a good point of clasping the young plant.
The growth of the plant ceases and flowering stops once the soils in which the plants are growing, dry, and possibly due to changes in photoperiod. The plant withers and dries and the achenes harden with the sharp spines pointing upwards. If the withered plant is not disturbed, the seeds drop around the site of the parent plant.
Plant TypeTop of page
DistributionTop of page
S. sessilis is common on North Island, New Zealand, especially in the north half of New Zealand and is scattered on the South Island (J Boow, Auckland regional Council, Taiao, New Zealand, personal communication, 2009). It has not been recorded in the Republic of Ireland (C O’Flynn, National Biodiversity Data Centre, Ireland, personal communication, 2009). Recent information on the distribution of this species in Oceania, Europe and Asia is limited.
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.Last updated: 10 Jan 2020
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|South Africa||Present||Introduced||1 occurrence listed|
|China||Present||Introduced||1 occurrence listed|
|Japan||Present||Introduced||1 occurrence listed|
|Taiwan||Present||Introduced||1 occurrence listed|
|France||Present||Introduced||2 occurences listed|
|Norway||Present||Introduced||1 occurrence listed|
|Portugal||Present||Introduced||3 occurences listed|
|Canada||Present||Present based on regional distribution.|
|-British Columbia||Present, Localized||2006||Introduced||1996||Invasive|
|Mexico||Present||Introduced||3 occurrences listed|
|United States||Present||Present based on regional distribution.|
|-California||Present, Widespread||2000||Introduced||Invasive||Coastal areas|
|-Hawaii||Present||Introduced||Invasive||Only on Big Island (Hawaii)|
|-North Carolina||Present, Localized||1965||Introduced||Invasive|
|-Oregon||Present, Widespread||1961||Coastal only|
|-South Carolina||Present, Localized||1965||Introduced||Invasive|
|Australia||Present||Present based on regional distribution.|
|-New South Wales||Present||2009||Introduced||Invasive||70 records|
|-South Australia||Present||2009||Introduced||Invasive||61 records (29 in Canberra area)|
|-Western Australia||Present||2009||Introduced||Invasive||16 records|
|Norfolk Island||Present||Introduced||1 occurrence listed|
|Bolivia||Present||1 occurrence listed|
|Peru||Present||Native||Also related species|
History of Introduction and SpreadTop of page
S. sessilis was first found in British Columbia, Canada in 1996 in Ruckle Provincial Park on Salt Spring Island (Castro, 2006). In 2006, a concerted effort was undertaken to identify other infested areas and a total of 22 infested sites were found on Vancouver Island and one site on the adjacent lower mainland of British Columbia (Polster, 2007).
HabitatTop of page
Habitat ListTop of page
|Terrestrial||Managed||Managed grasslands (grazing systems)||Principal habitat||Harmful (pest or invasive)|
|Terrestrial||Managed||Disturbed areas||Principal habitat|
|Terrestrial||Managed||Urban / peri-urban areas||Principal habitat|
|Littoral||Coastal areas||Secondary/tolerated habitat|
ClimateTop of page
|Cs - Warm temperate climate with dry summer||Preferred||Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers|
Latitude/Altitude RangesTop of page
|Latitude North (°N)||Latitude South (°S)||Altitude Lower (m)||Altitude Upper (m)|
Air TemperatureTop of page
|Parameter||Lower limit||Upper limit|
|Absolute minimum temperature (ºC)||-10|
|Mean annual temperature (ºC)||4||30|
Rainfall RegimeTop of page
Soil TolerancesTop of page
- seasonally waterlogged
Means of Movement and DispersalTop of page
Natural Dispersal (Non-Biotic)
Pathway VectorsTop of page
Impact SummaryTop of page
Economic ImpactTop of page
The economic impacts of S. sessilis centre on the costs associated with its control and the restoration of sites degraded by this species (R Cranston, Invasive Plant Council of British Columbia, Canada, unpublished data). Although this species is relatively easy to control using standard herbicides (although herbicide resistance exists; see the Control text section), costs associated with this method of control can be attributed to invasion by S. sessilis. In addition, costs associated with revegetation of bare turf areas that have been caused by this species need to be included in the economic impact of this species (R Cranston, Invasive Plant Council of British Columbia, Canada, unpublished data). Maintaining healthy turf can help prevent the establishment and spread of S. sessilis (Harrington, 2009).
Environmental ImpactTop of page
S. sessilis usually occurs in areas of degraded turf and may cause increased erosion by creating bare areas that are unprotected during winter storms. Also, without a healthy turf cover, rainfall may be prone to running off rather than soaking into the soil, reducing the recharge of groundwater supplies. It has established in natural coastal bluff ecosystems at Ruckle Provincial Park on Salt Spring Island, British Columbia, Canada where it is displacing Limnanthes macounii, an endemic species (Government of British Columbia, 2009) and one that is listed as threatened by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC, 2009). Although S. sessilis is considered primarily a pest of degraded turf, the potential to move into Garryoak and associated ecosystems has caused concern (GOERT, 2009).
Threatened SpeciesTop of page
Social ImpactTop of page
The spines on the achenes of S. sessilis make walking on turf in bare feet unpleasant (Harrington, 2009). It is considered one of the most hated turf weeds in New Zealand as it grows below the blades of lawn mowers and makes walking on lawns in bare feet painful (Harrington, 2009). The tips of the spines can break off in the skin causing infections and painful slivers. The spines can cause lameness in dogs. The brown patches caused by this species on golf courses can impact the roll of the ball and degrade the quality of the golf course (R Cranston, Invasive Plant Council of British Columbia, Canada, unpublished data). Cranston suggests that the impacts of S. sessilis infestations could include reduced revenue at infested golf courses; reduced revenue in parks and recreation areas due to loss of aesthetic value and the nuisance of prickly seeds. In addition, it has been suggested that there would be a cost associated with government officials dealing with complaints from the public (R Cranston, Invasive Plant Council of British Columbia, Canada, unpublished data).
Risk and Impact FactorsTop of page
- Proved invasive outside its native range
- Highly adaptable to different environments
- Is a habitat generalist
- Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
- Pioneering in disturbed areas
- Tolerant of shade
- Highly mobile locally
- Benefits from human association (i.e. it is a human commensal)
- Fast growing
- Has high reproductive potential
- Has high genetic variability
- Damaged ecosystem services
- Ecosystem change/ habitat alteration
- Increases vulnerability to invasions
- Infrastructure damage
- Modification of successional patterns
- Monoculture formation
- Negatively impacts human health
- Negatively impacts animal health
- Negatively impacts tourism
- Reduced amenity values
- Reduced native biodiversity
- Threat to/ loss of endangered species
- Threat to/ loss of native species
- Competition - smothering
- Interaction with other invasive species
- Rapid growth
- Produces spines, thorns or burrs
- Highly likely to be transported internationally accidentally
- Difficult to identify/detect as a commodity contaminant
- Difficult to identify/detect in the field
- Difficult/costly to control
DiagnosisTop of page
No specific laboratory techniques have been applied to S. sessilis, although Harrington (2009) has conducted detailed studies in conjunction with herbicide resistance assessments.
Detection and InspectionTop of page
S. sessilis is hard to find as first year seedlings because the plants look like the seedlings of several other weedy species including: Matricaria discoidea; Geranium molle; Daucus carota; Aphanes spp.; and Achillea millefolium. In addition, the young plants are small and blend easily with turf and/or mosses. However, if the plants are not disturbed and if the seeds remain near the parent plant, then a clump of S. sessilis establishes that is much easier to find. Once a carpet forms, this species is easily identified by knowledgeable personnel.
Similarities to Other Species/ConditionsTop of page
S. sessilis looks like the following species that occupy similar habitats, but with some differences: Matricaria discoidea; Aphanes arvensis; and Daucus carota. M. discoidea is a common weedy species of compacted trails, parking lots, roadsides and other similar sites; it has dissected leaves, but lobes that extend far down the rachis. A. arvensis is similar, but with rounded dissected leaves. D. carota has more uniformly dissected leaves than S. sessilis and does not have the arching habit that S. sessilis leaves and stems have. In addition, young Achillea millefolium plants have much more finely divided leaves than S. sessilis, as does Lomatium utriculatum. Foliage colour and texture can aid in finding young S. sessilis plants among other similar species, although when the plants are very young, they can blend in with mosses and other seedlings (Castro, 2006).
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.
ReferencesTop of page
Dutra IS, Hing Man Way M, Mello Filho AT, Machado PR, Silva SA, 1980. Tebuthiuron pellets to control weeds in pastures. (Tebutiuron peletizado no controle de plantas invasoras nas pastagens.) In: Resumos XIII Congresso Brasileiro de Herbicidas e Ervas Daninhas, Bahia, 1980, 70.
Lawson RN, Unruh JB, Brecke BJ, 2002. Lawn burweed (Soliva pterosperma) control in hybrid bermudagrass (Cynodon dactylon × C. transvaalensis) and common centipedegrass (Eremochloa ophiuroides). Weed Technology, 16(1):84-87.
Lorenzi H, 1982. Plantas Daninhas do Brasil. Author's edition. Nova Odessa, San Paulo, Brazil: H. Lorenzi, 400 pp.
Polster DF, 2007. Eradicating carpet burweed (Soliva sessilis Ruiz & Pavón) in Canada. In: 'Invasive plants: inventories, strategies and action', a symposium held in Victoria, Canada, in November 2006 [ed. by Clements DR, Darbyshire SJ] Sainte-Anne-de Bellevue, Canada: Canadian Weed Science Society, 71-81.
USDA-ARS, 2010. Germplasm Resources Information Network (GRIN). Online Database. Beltsville, Maryland, USA: National Germplasm Resources Laboratory. https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearch.aspx
CABI, Undated. CABI Compendium: Status inferred from regional distribution. Wallingford, UK: CABI
Castro K, 2006. Weed Risk Assessment Carpet Burweed (Soliva sessilis Ruiz & Pav.). In: Weed Risk Assessment Carpet Burweed (Soliva sessilis Ruiz & Pav.), Ottawa, Ontario, Canada: Plant Health Risk Assessment Unit, Canadian Food Inspection Agency.
USA, USDA-ARS, 2010. Germplasm Resources Information Network (GRIN). Online Database. In: Germplasm Resources Information Network (GRIN). Online Database, Beltsville, USA: National Germplasm Resources Laboratory. http://www.ars-grin.gov/cgi-bin/npgs/html/tax_search.pl
ContributorsTop of page
15/07/09 Original text by:
D Polster, Polster Environmental Services Ltd, 5953 Deuchars Drive, Duncan, BC V9L 1L5, Canada
Distribution MapsTop of page
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CABI Summary Records
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