Senecio glastifolius (holly-leaved senecio)
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- History of Introduction and Spread
- Risk of Introduction
- Habitat List
- Hosts/Species Affected
- Biology and Ecology
- Latitude/Altitude Ranges
- Air Temperature
- Natural enemies
- Notes on Natural Enemies
- Means of Movement and Dispersal
- Impact Summary
- Economic Impact
- Environmental Impact
- Risk and Impact Factors
- Detection and Inspection
- Similarities to Other Species/Conditions
- Prevention and Control
- Gaps in Knowledge/Research Needs
- Links to Websites
- Principal Source
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Senecio glastifolius L. f.
Preferred Common Name
- holly-leaved senecio
International Common Names
- English: woad-leaved ragwort
Local Common Names
- New Zealand: pink ragwort; purple ragwort
- South Africa: large senecio; water thistle; waterdissel
- UK: holly-leaved groundsel; lilac senecio
- USA: lilac-flowered groundsel
Summary of InvasivenessTop of page
Senecio glastifolius is an erect perennial herb, native to the Eastern and Western Capes of South Africa. It is sold commercially as an ornamental and is often planted in gardens. It is known to have been introduced to Madeira, the UK and California in the USA and is recorded as invasive in Australia and New Zealand. It grows in shrubland and rocky, damp areas such as riverbanks. Where it is invasive, it grows in disturbed areas, agricultural land, open woodlands and coastal areas. In suitable habitats it is an extremely aggressive weed, producing large numbers of wind dispersed seed, and spreading rapidly, forming dense stands and potentially outcompeting native biodiversity. Ecological niche modelling revealed that, if introduced, this species could become invasive across large areas of the world including the west coasts of Canada, USA and South America and parts of Europe and Africa. Early detection and removal of seedlings, often garden escapes, is likely to be the most effective method of control. In New Zealand, infestations are largely controlled by hand-pulling of plants; however some commercially available herbicides have proved effective. The sale of this species has been banned in Tasmania, Australia and the Taranaki region of New Zealand.
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Spermatophyta
- Subphylum: Angiospermae
- Class: Dicotyledonae
- Order: Asterales
- Family: Asteraceae
- Genus: Senecio
- Species: Senecio glastifolius
Notes on Taxonomy and NomenclatureTop of page
The genus Senecio is cosmopolitan and one of the largest genera of seed-producing plants (spermatophytes), often having toxic or medicinal properties (Mabberley, 1997), though none are specifically recorded for S. glastifolius.
The name Senecio is derived from the Latin ‘senex’ meaning 'old man', probably referring to the bearded, fluffy white seeds of species in the genus. The species epithet ‘glastifolius’ relates to it having leaves like dyer's woad or glastum (Isatis tinctoria).
Historically, S. glastifolius has been incorrectly named as S. lilacinus. It is commonly known as holly-leaved senecio, woad leaved ragwort and pink ragwort.
DescriptionTop of page
S. glastifolius is an erect perennial herb, often with woody lower stems. Typically it grows to a height of about 1 m (Webb et al., 1988), but plants in sheltered conditions frequently grow to over 2 m tall. However, the majority of plants in the Manawatū region of New Zealand are <1.2 m tall, and it rarely reaches 2 m in Australia. Williams et al. (1999) report stems of 8 cm in diameter, but stems which are 9 cm in diameter at the narrowest point have been measured, with the base up to 11 cm diameter (G Rapson, Massey University, Palmerston North, unpublished data).
S. glastifolius is reported as an annual by the New Zealand Plant Conservation Network (2017), but observations suggest it is mostly perennial in New Zealand. Seedlings are generally vegetative for their first year, and possibly longer, though they can certainly flower when less than one year old. The plants are not monocarpic and they flower annually, inflorescence increasing in abundance as they grow. Williams et al. (1999) suggested the maximum age of S. glastifolius is four years, but this seems unlikely, as observations suggest plants continue to grow until they collapse, when they appear capable of layering. However, large plants in particular tend to be targeted for control, so their potential lifespan is unclear.
Foliage is holly-like, with glabrous, alternate leaves, typically a bright but deep green in colour. Leaves have large irregular teeth, about 0.8 cm apart, with acute apices which occur along the margins and at the tip. This makes the leaves distinctly prickly to the touch, rendering the stems unpleasant to grasp. Leaves are elliptic, apetiolate (i.e. stalkless or sessile), and bases are clasping or decurrent or sheathing, encircling the stem in young plants. Leaves are usually around 8 cm long, but range from 3-15 cm long, by 2-3 cm wide. At the base of the plant, leaves are usually longer, declining in size up the stem, to about 3 cm on the flowering stems, where they are also less serrate. Leaves arise every 1-2 cm along the stems, and persist for 2-4 years, so there are always green leaves near the inflorescence. At the base of the stems the lower leaves die and remain attached for a few months before the stem becomes leafless.
The inflorescences are capitula, occurring in loose, flat-topped corymbs, often of 20-30 capitula, and the corymbs themselves are on stems branched 2-4 times, giving an extensive and complete covering of inflorescences over the foliage. Up to 400 capitula have been seen on a single plant in New Zealand, and several hundred are reported in Western Australia. Capitula are 40-50 mm in diameter. The capitulum has a few supplementary bracts of 3-5.5 mm long. It is also surrounded by a single green ring of bracts, each 6-9 mm long, topped with a small, dark red to black apiculus. There are 19-23 bracts per capitulum.
The inflorescences have both ray and disk florets. The disk florets are yellow and 6-8 mm long. Counts of 27 capitula from nine individuals in the Manawatū gave a mean of 189 disc florets and 13.3 ray florets, with a range of 156-240, and 12-17 respectively. Numbers were more consistent within an individual. The ray florets are around (12-)20-25 mm long and occur in one ring.
The colour of the ray florets is extremely variable. They are described as mauve or purple in South Africa and are described in the Flora of New Zealand as mauve-pink or pale to deep pink (Webb et al., 1988). However, white or whitish-pink forms are also known. Generally, they are a bright pink, described as a "light hot pink", though some are very dark pink. Colour is generally uniform within a single plant.
Fruits are dark-brown, terete achenes to 2-2.5 mm long, those of the ray florets being glabrous, while the disk florets produce hairy achenes. Seeds are 2 mm long and the pappus is about 8 mm (7-9 mm) long, and is caducous (detaches from the seed). Seeds weigh 0.6-0.8 mg (Williams et al., 1999).
The stems are glabrous, softly woody in their lower parts, rather brittle and easily broken at the stem junction and even along the upper branches. There are fine ridges (striations), often reddish in colour, running vertically on the green stems, which merge with the foliage.
Below the first branch the stem can be 8-12 cm or more in diameter. Stems branch from near the base. Usually there are 3-5 main branches per plant, and these also branch repeatedly. The wood anatomy of S. glastifolius is not well understood. The plants form growth rings, at least in colder climates, though these are not especially distinct.
DistributionTop of page
S. glastifolius is native to the Eastern and Western Capes of South Africa (USDA-ARS, 2017). In the Eastern Cape it occurs on the southern coast from George to Humansdorp (34°S, 21-26°E) (SANBI, 2002). Its altitudinal range is up to 330 m above sea level (Williams et al., 1999), though Germishuizen and Meyer (2003) reported plants occurring up to elevations of 1090 m.
This species has been introduced to Australia and New Zealand where it has become naturalized and invasive. In Western Australia, S. glastifolius is weedy in Albany, covering an area of about 100 km2. Plants are spreading from this area and are now found up to 20 km away (Australian Government, 2003). It was originally recorded in Manjimup (Thompson, 2006), but it is no longer believed to be there (Beautrais, 2013). In New South Wales, S. glastifolius has been present in the Royal National Park in the vicinity of Bundeena, near Sydney, since 1991 (Australian Government, 2003). Beautrais (2013) mapped a now historic record about 20 km further north, dated 1953. In New Zealand, this species occurs primarily in coastal areas on the North Island but also in some inland areas and on the north coast of the South Island close to Nelson (Beautrais, 2013; Council of Heads of Australasian Herbaria, 2017). A particularly heavy infestation is located along State Highway 1 just north of Wellington.
S. glastifolius has also been introduced in the Scilly Isles, UK, where it was first recorded in 1971 (Stace, 1997; Preston et al., 2002), and in Tresco, Cornwall, UK (Parslow, 2010). Apparently it also occurs on rough ground in Guernsey (Beautrais, 2013). Hansen and Sunding (1993), Silva (2002) and Jardim and Sequeira (2008) record S. glastifolius as naturalized in Madeira. Roscoff Gardens on the Brittany coast in France holds images of S. glastifolius appearing as feral around the gardens, however its status is unverified. In the USA, INaturalist (2017) notes a population of S. glastifolius near Sentinel Dome in the Yosemite Valley, California. Its status is also unverified.
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|
|South Africa||Present||Native||USDA-ARS, 2017||Eastern Cape, Western Cape|
|USA||Unconfirmed record||Introduced||Based on regional distribution|
|-California||Unconfirmed record||Introduced||INaturalist, 2017||Near Sentinel Dome, Yosemite National Park|
|Portugal||Present||Introduced||Present based on regional distribution|
|-Madeira||Present||Introduced||Hansen and Sunding, 1993; Silva, 2002; Jardim and Sequeira, 2008||Naturalized|
|UK||Present||Introduced||1971||Stace, 1997; Preston et al., 2002; Parslow, 2010||Scilly Isles, naturalized|
|Australia||Localised||Introduced||Invasive||Australian Government, 2003|
|-New South Wales||Localised||Introduced||Invasive||Australian Government, 2003||Bundeena|
|-Western Australia||Localised||Introduced||Invasive||Australian Government, 2003||Albany|
|New Zealand||Present||Introduced||1963||Invasive||Webb et al., 1988; Timmins and Braithwaite, 2003; Beautrais, 2013|
History of Introduction and SpreadTop of page
S. glastifolius was first recorded in New Zealand in 1963 near Gisborne and an early outbreak was noted from wasteland adjacent to a nursery there (Beautrais, 2013). However, Williams et al. (1999) do not regard the species as an escape from cultivation in New Zealand. In 1987, Webb (1987) listed it as present in Gisborne city, Havelock North, Mana Island and in the vicinity of Wellington city on the North Island and Motueka (Nelson) and Canterbury on the South Island. Webb et al. (1988), refined its southern-most distribution as Christchurch on the South Island.
S. glastifolius was not considered a threat to the natural environment anywhere in New Zealand even in the 1990s, when Owen (1996) did not record it in a survey of conservation weeds. However, Williams et al. (1999) reported that it was common in the Tawa/Linden suburbs of Wellington city in the late 1960s (Beautrais, 2013, gives the date as 1963) and from there it has spread rapidly. It was first recorded at Whanganui in 1990 and has spread both to the north and south up to 20 km along the coast. In between these two infestations a single plant was noted on the Manawatū coast, at Tawhirihoe Scientific Reserve (a coastal dune reserve) by NJD Singers in 1994 (Singers, 1997), probably sourced from across the bight from Whanganui. S. glastifolius has subsequently become a common plant along the rear dunes, rough scrubland and pine plantations of the outermost 5-6 km of the Manawatū coast (the mobile sand country), from Foxton to Tangimoana. Probably sourced from there, scattered plants have been found up to 30 km inland, particularly along the foothills of the Tararua ranges, presumably from wind-blown seed carried on the strong westerly winds. However, Beautrais (2013) reported that it was already present in the foothills in 1972 as a "local weed in waste areas" in Palmerston North (MPN 254437). While many isolated and scattered plants have been manually pulled over the last two decades, several sites have still developed large infestations in the Manawatū.
S. glastifolius was first recorded on the 217 ha, disturbed coastal island of Mana, near Wellington, in 1984 (Beautrais, 2013). Although plants were pulled out in the early 1980s, without the necessary follow-up, the species had become "widespread" by 1987 (Timmins and Braithwaite, 2003).
S. glastifolius occurred on a causeway near Motueka in 1970 and, to date, plants are occasional in this area (Beautrais, 2013). However, there is currently no known population in the Port Hills of Christchurch, the original invader apparently having died out (Williams et al., 1999). It is not currently present in the Taranaki region to the north of Whanganui, but control and containment preparations have already been made (TERRAIN, 2017).
In Australia, S. glastifolius was first accessioned in Western Australia in 1953 (PERTH 005454965; Beautrais, 2013), and has been regarded as weedy since 1986 in the Mt Adelaide and Mt Clarence Nature Reserve (Australian Government, 2003). The source was a plant in a home garden in Albany. The small population, originally restricted to Mt Adelaide, became an infestation after fire (Keighery, 1999). However, it is undergoing eradication efforts, which were planned to be completed by 2016.
Prior to 1991, in New South Wales, it escaped from cultivation at Bundeena, Sydney, forming a coastal population (Australian Government, 2003).
Details of the introduction and spread of S. glastifolius in California are not known.
S. glastifolius is cultivated in France and the UK, but the only report of its naturalization is on the Scilly Isles, where it is a garden escape naturalized in open woodland and on rubbish tips (Stace, 1997).
IntroductionsTop of page
Risk of IntroductionTop of page
In a study of bioclimatic niche patterns for species in their home range of South Africa, Thuiller et al. (2005) modelled and mapped the global areas of potential habitat for S. glastifolius. These included:
North and South America:
- much of the western seaboard of the USA
- the coast of British Columbia, Canada
- the western seaboard of South America, but with southern Peru and northern Chile less acceptable
- the Sao Paulo area
- the Falkland Islands
- western Scotland
- southwest England
- the Atlantic coasts of France and Spain
- Madagascar and South Africa, but both at lower risk
- New Guinea
- the Western Australia coast from Cape Leewin to Albany
- coast of Tasmania
- southern coast of Victoria from Cape Howe, west to Adelaide
- much of the coast and lowlands of the North Island
- much of the northern coasts of the South Island, and of the southern coasts, both east and west
- Stewart Island coasts
The threatened areas noted by Thuiller et al. (2005) include six global biodiversity hotspots, namely the Mediterranean Basin, California Floristic Province, Chocó-Darién Western Equator, Central Chile, Southwest Australia and New Zealand. With 48 South African species already invasive in Australia and 34 in New Zealand (Thuiller et al., 2005), further extension of the existing ranges of S. glastifolius in these areas seems inevitable. Further, increasing tourism increases invasion rates into Western Europe and the Mediterranean.
In Victoria, Australia, the climate-matching program, CLIMATE (Pheloung, 1996), was used by Agriculture Victoria (2017) to predict the potential distribution of S. glastifolius, based on the climate in overseas localities where it occurs. Results suggested that coastal habitat is the most suitable.
In New South Wales, Australia, Downey et al. (2010) include S. glastifolius as number 332 on a prioritized list of 340 naturalized plant species in New South Wales that have invasive potential. S. glastifolius is also on Australia's National Alert List for Environmental Weeds (Glanznig and Kessal, 2004), which has 28 species of concern. Weber and Panetta (2006) rated S. glastifolius as having a weediness score of 34 (the highest possible score is 47) and it is a terrestrial weed examined in the DEH (Department of Environment and Heritage) Alert List, so is recommended for containment or eradication.
In New Zealand, Beautrais (2013) used Species Distribution Modelling to describe how S. glastifolius is limited by its environment. The variables used were aridity, mean annual temperature range and minimum temperature of the coldest month. The suitable, though currently uninvaded areas are: "most of the northern half of the North Island and associated offshore islands [and] the entire western coast, ... the Wairarapa and southern Hawkes Bay, plus inland Whanganui and Manawatū ... [as well as] the coastal northern third" of the South Island (Beautrais, 2013).
Beautrais (2013) also predicted that the potential habitat for S. glastifolius extends along much of the southern coast of Australia and much of Tasmania, as well as the southern coast of South Africa. The author added that while the South African and New Zealand populations overlap in terms of their temperature range, there is almost no overlap in terms of humidity, so that in New Zealand the niche of S. glastifolius appears to have shifted to a more moist climate. Low winter temperatures probably prevent it occupying extremely dry areas of New Zealand, and wetter areas are not available in South Africa.
Further climate change is expected to impact on potential distributions. For example, Williams et al. (2012) stated, with respect to Queensland, Australia, that "under the current climate, only southeast Queensland contains suitable habitat for the holly-leaved senecio (S. glastifolius), whereas under future scenarios, suitable climatic space for this species contracts southward and the species may cease to exist in Queensland."
HabitatTop of page
In South Africa, S. glastifolius occupies fynbos (fine-leaved heathland or shrubland) with species of the Restionaceae and Proteaceae families. It also occurs on rocky hillsides and in damp areas, e.g. riverbanks and marshy ground (Williams et al., 1999). Despite being within its native range, Wells et al. (1986) regard S. glastifolius as a potential problem plant for South Africa as it is common in the understory of plantation forests and on pastoral land in wetter, disturbed areas; it also spreads after disturbance, particularly fire.
In Albany, Australia, S. glastifolius occurs on grey sand and swampy loams on hillslopes (FloraBase, 2013). It now dominates the understorey vegetation of woodlands of jarrah (Eucalyptus marginata), blackbutt (E. pilularis) and marri (Corymbia haematoxylon) and open woodlands of Allocasuarina (Australian Government, 2003). It is noted as particularly invasive in open, damp areas. Potential habitat in Victoria is mainly coastal (Agriculture Victoria, 2017). It occurs in open areas, such as open woodland, shrubland, hillsides, coastal dunes, roadsides and near waterways (Australian Government, 2003).
In New Zealand, the habitat of S. glastifolius includes wastelands, hillsides, pasture, scrubland and river beds (Webb et al., 1988). It is particularly common on disturbed slopes above motorways (especially State Highway 1, north of Wellington) and in open dunes around the Manawatū coast.
In the Scilly Isles, UK, S. glastifolius occurs in open woodland near a rubbish tip (Stace, 1997).
Habitat ListTop of page
|Terrestrial – Managed||Managed forests, plantations and orchards||Secondary/tolerated habitat||Harmful (pest or invasive)|
|Managed forests, plantations and orchards||Secondary/tolerated habitat||Natural|
|Disturbed areas||Principal habitat||Harmful (pest or invasive)|
|Disturbed areas||Principal habitat||Natural|
|Rail / roadsides||Principal habitat||Harmful (pest or invasive)|
|Rail / roadsides||Principal habitat||Natural|
|Terrestrial ‑ Natural / Semi-natural||Natural forests||Principal habitat||Harmful (pest or invasive)|
|Natural forests||Principal habitat||Natural|
|Riverbanks||Principal habitat||Harmful (pest or invasive)|
|Rocky areas / lava flows||Principal habitat||Harmful (pest or invasive)|
|Rocky areas / lava flows||Principal habitat||Natural|
|Scrub / shrublands||Principal habitat||Harmful (pest or invasive)|
|Scrub / shrublands||Principal habitat||Natural|
|Coastal dunes||Principal habitat||Harmful (pest or invasive)|
|Coastal dunes||Principal habitat||Natural|
Hosts/Species AffectedTop of page
There are no known effects of this species on crops in New Zealand, as the plant is restricted to wasteland and coastal areas. It does occur among scrub in extensively grazed farmland, where it may eventually come to restrict productivity of preferred forage plants.
Biology and EcologyTop of page
The base haploid chromosome number of the genus Senecio is 10 (Pelser et al., 2007), and species are generally 2n = 20 or 2n = 40, although some New Zealand populations have a chromosome number of 2n = 80 or 100 (Memory, 2012).
Using chloroplast DNA, Khan et al. (2013) reported S. giessii and S. sisymbrifolius as the closest relatives of S. glastifolius; S. windhoekensis and Erechtites diversifolia are also closely related. Of these, all are from South Africa or western Africa, except for E. diversifolia, which is from the South Island of New Zealand. Pelser et al. (2007), using the ITS region of the DNA, placed S. glastifolius with S. achilleifolius near S. windhoekensis, though Milton (2009) argues this is a misidentification and commonly associates S. glastifolius with S. giessii and E. diversifolia.
Little is known about the reproductive biology of S. glastifolius. It appears to set seed readily in the wild, suggesting it is self-compatible and dispersed by the wind. Capitula produce up to 250 seeds each. In South Africa it is pollinated by bees, and is also visited by butterflies and birds.
Seed appears to germinate readily (within 2 weeks). Germination success ranges from 53-80% and appears to be higher at temperatures above 25°C (Williams et al., 1999). Fire followed by rains encourages germination (Australian Government, 2003). Seeds are viable for several years in soil seedbanks and slashing woodland, cultivation and fires all apparently release seeds from dormancy (Australian Government, 2003; FloraBase, 2013).
Individual plants of S. glastifolius live for at least 3-5 years, while the existence of a few very large plants persisting in sheltered situations, suggests that they can live for at least a decade. In Western Australia it grows between March and August, with germination over the same period, flowering from September to October and fruiting in November and December (FloraBase, 2013).
Flowering predominantly occurs in spring (September to October in New Zealand and South Africa, February to June in California) but occasional second flowerings have been recorded in the summer (January to February in the southern hemisphere).
In New Zealand, detached capitula do not usually result in any germinants (G Rapson, Massey University, Palmerston North, personal observation).
Williams et al. (1999) list a number of species associated with S. glastifolius, largely in the Wellington region of New Zealand. These tend to be common coastal scrub exotics known from Ulex europaeus, exotic grass and Chrysanthemoides monilifera habitats, along with occasional natives such as Ficinia nodosa, Muehlenbeckia australis and Spinifex sericeus.
In Australia, S. glastifolius is found in forests with Eucalyptus marginata, E. pilularis and Corymbia haematoxylon and in open woodlands of Allocasuarina (Australian Government, 2003).
Beautrais (2013) found that acute cold stress (mean minimum daily air temperature for the coldest month in the range 0-3°C) could limit the distribution of S. glastifolius.
ClimateTop of page
|Cs - Warm temperate climate with dry summer||Preferred||Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers|
|Cf - Warm temperate climate, wet all year||Preferred||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)|
Air TemperatureTop of page
|Parameter||Lower limit||Upper limit|
|Mean minimum temperature of coldest month (ºC)||0-3|
Natural enemiesTop of page
Notes on Natural EnemiesTop of page
Westhuizen et al. (2010) noted damage by a common defoliating moth (Diota rostrata: Noctuidae, Arctiinae), which is widespread in southern Africa, but in no-choice trials it showed only limited feeding and no survival.
Williams et al. (1999) report herbivory in New Zealand by Nyctemera annulata, the native magpie moth, while Aglossa caprealis, the diurnal moth, feeds on the flowers.
A spittle bug has been seen on the plant in shrubland in New Zealand, but this does not appear to impede its growth in any way. Sheep apparently do browse foliage although it is potentially toxic, but cattle do not seem to graze it (Popay et al., 2010).
Means of Movement and DispersalTop of page
Natural Dispersal (non-biotic)
Seeds are small and readily dispersed by wind (Kriticos et al., 2018).
Plants may establish from stem fragments in Western Australia, presumably after slashing. This has not been observed in New Zealand, though some layering and adventitious rooting does occur. Seed is also spread by vehicles/machinery in Western Australia. New invasions may occur where plants escape gardens. Accidental introduction further afield is unlikely, though seed smuggling remains a possibility.
S. glastifolius may be intentionally introduced as an ornamental. However, it is now banned from sale in Tasmania, Australia (Tasmanian Government, 2017) and the Taranaki region of New Zealand (TERRAIN, 2017).
Impact SummaryTop of page
Economic ImpactTop of page
S. glastifolius is an aggressive invader, reducing productivity on agricultural land in Australia.
Environmental ImpactTop of page
To date, the information on environmental impact of S. glastifolius suggests it is mainly an aesthetic offence, but stands of the plant can become so dense that smaller or less aggressive natives will be out-competed. In Australia, it is one of 28 species on the National Alert List for Environmental Weeds and in Western Australia it is targeted for eradication. In Albany, S. glastifolius quickly establishes post-fire and dominates. In New Zealand, a model illustrating the potential distribution of S. glastifolius found that it is likely to primarily affect coastal dunes (Kriticos et al., 2018).
Risk and Impact FactorsTop of page Invasiveness
- Proved invasive outside its native range
- Highly adaptable to different environments
- Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
- Pioneering in disturbed areas
- Highly mobile locally
- Long lived
- Fast growing
- Has high reproductive potential
- Has propagules that can remain viable for more than one year
- Monoculture formation
- Negatively impacts agriculture
- Reduced amenity values
- Reduced native biodiversity
- Threat to/ loss of endangered species
- Threat to/ loss of native species
- Competition - monopolizing resources
- Competition - shading
- Rapid growth
- Highly likely to be transported internationally deliberately
- Difficult to identify/detect as a commodity contaminant
UsesTop of page
This species has been commercialized as an ornamental and is sold in garden centres.
S. glastifolius is often grown in gardens around the world, due to its showy pink flowers. In New Zealand it is also enjoyed along highways in the Wellington region.
Bees visit the flowers and presumably feed on nectar or pollen.
Detection and InspectionTop of page
S. glastifolius is extremely easy to detect during the flowering season, but is rather cryptic at other times, at least in New Zealand. Searching for new infestations or remnants is best done during the flowering period (early spring).
Similarities to Other Species/ConditionsTop of page
S. glastifolius is very conspicuous, at least in the New Zealand flora, because of its dense heads of bright pink capitula, which appear around October. No native plants can be confused with it, and based on its colour it most resembles the South African exotic S. elegans, a small succulent-leaved plant found on coastal dunes, which has ray florets of a much deeper purple. S. glastifolius is also rather like the exotic ragwort (S. jacobaea), which is also weedy in New Zealand (if biocontrol agents are absent), but this has yellow ray florets, lobed leaves, and is shorter and less woody.
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.
It is recommended that detected seedlings and adults are removed as quickly as possible, before flowering is completed.
The public should be discouraged from planting S. glastifolius in gardens, as it is likely to escape.
Eradication of S. glastifolius outside desired zones or natural ranges is strongly recommended and is being attempted in Albany, Australia.
In Western Australia, eradication was the aim of the Department of Environment and Conservation and was "largely achieved" after seven years, with the caveat that at least five years of follow-up, including in private gardens, is needed to ensure new seedlings are removed (Government of Western Australia, 2017).
In New Zealand, persistent hand-weeding over three or more years can eliminate small infestations.
If early invaders of S. glastifolius are neglected in vulnerable areas then prolific flowering results in stands or populations that are so large and vigorous that spraying becomes the most appropriate control option. The preferred means of control in New Zealand is containment by hand-weeding of the isolated plants at the edges of its range, preventing new populations from developing.
S. glastifolius has been managed routinely in the Manawatū district of New Zealand for the past two decades by hand-pulling of individual plants during the flowering season (early spring), when plants can be easily located. In most environments, S. glastifolius is easily removed by pulling of the plant, holding the stem near its base. Due to the prickly nature of its leaves, including those that have died around the bases of the stems, gloves are recommended when hand-pulling, especially if there are more than fifty plants to pull. Once pulled, the stems are then folded back and partially broken to reduce the supply of resources from the disinterred rootstock to any developing seed and the plants are left out to dry. Seed set in this situation seems to be minimal, so there is little chance of the infestation spreading. In the most infested areas, e.g. dunes, this is a very easy and effective control mechanism and very little seed set, if any, takes place in plants treated in this way. If areas are protected from reinfestation, and are regularly treated in this way for 2-3 years, then eradication appears to be achievable.
However, grubbing or hand-pulling is not recommended by TERRAIN (2017) as the plants will regrow from root fragments, though this information may refer to ragwort (S. jacobaea). In Western Australia, pulled plants left on site continued to set seed (Australian Government, 2003), so FloraBase (2013) recommend that seed heads be burnt or otherwise destroyed to prevent seed ripening.
S. glastifolius should not be transported, or sold via garden centres, as Groves et al. (2005) rate it amongst the ten weediest species available for sale in Australia.
The Taranaki Regional Council, New Zealand, where S. glastifolius is not present, has banned it from sale and has an established plan to eradicate any invaders (TERRAIN, 2017). Similarly it is banned in Tasmania, Australia.
There are no known biological control agents for S. glastifolius (Froude, 2002). However, studies carried out by Brierley (1953) on the host range of chrysanthemum stunt virus found 39 plant varieties, including S. glastifolius, which were susceptible and developed recognizable symptoms.
Atkinson (1980) tested a range of selective and non-selective herbicide sprays on S. glastifolius at the onset of flowering in the Gisborne District. Glyphosate was ineffective against small plants and seedlings, however 2,4-D+picloram and triclopyr all produced good results but not until four months after treatment.
Spraying with a commercially available herbicide, containing 100 g/L 2,4-D and 50 g/L dicamba appeared to be effective in trials (G Rapson, Massey University, Palmerston North, personal observation).
In Australia, FloraBase (2013) recommend applying a herbicide in autumn (before flowering) that contains clopyralid. Clopyralid (3,6-dichloro-2-pyridinecarboxylic acid) is a selective herbicide used for control of broadleaf weeds, especially thistles and clovers.
Monitoring and Surveillance (incl. remote sensing)
New invasion points could readily be detected by remote sensing, including drone technology, during the flowering season, as the flower colour and the density of the flowering heads makes the species easily identifiable. Surveillance by vehicle is also achievable where land is reasonably flat and road networks are sufficiently dense, as plants can be identified up to 0.5 km away.
Gaps in Knowledge/Research NeedsTop of page
Very little is known about the growth, ecophysiology, environmental preferences or demography of S. glastifolius.
ReferencesTop of page
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Principal SourceTop of page
Draft datasheet under review
ContributorsTop of page
10/11/17 Original text by:
Gillian l Rapson, Institute of Agriculture and Environment, Massey University, Palmerston North, New Zealand
Distribution MapsTop of page
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