Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Datasheet

Salix cinerea
(grey sallow)

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Datasheet

Salix cinerea (grey sallow)

Summary

  • Last modified
  • 27 September 2018
  • Datasheet Type(s)
  • Invasive Species
  • Host Plant
  • Preferred Scientific Name
  • Salix cinerea
  • Preferred Common Name
  • grey sallow
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Plantae
  •     Phylum: Spermatophyta
  •       Subphylum: Angiospermae
  •         Class: Dicotyledonae
  • Summary of Invasiveness
  • S.cinerea was introduced from its native Eurasia mainly for riverbank stabilization. It is now a serious threat to riparian and wetland environments in New Zealand, southeastern Australia and increasingl...

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Pictures

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PictureTitleCaptionCopyright
Salix cinerea (3 m high) in its characteristic habitat. River Stella, Friuli, Northern Italy.
TitleTree habit
CaptionSalix cinerea (3 m high) in its characteristic habitat. River Stella, Friuli, Northern Italy.
CopyrightPaola Paiero
Salix cinerea (3 m high) in its characteristic habitat. River Stella, Friuli, Northern Italy.
Tree habitSalix cinerea (3 m high) in its characteristic habitat. River Stella, Friuli, Northern Italy.Paola Paiero
Branch of Salix cinerea with typical hairy leaves.
TitleLeaves
CaptionBranch of Salix cinerea with typical hairy leaves.
CopyrightPaola Paiero
Branch of Salix cinerea with typical hairy leaves.
LeavesBranch of Salix cinerea with typical hairy leaves.Paola Paiero
Twig of Salix cinerea with male catkins.
TitleMale flowers
CaptionTwig of Salix cinerea with male catkins.
CopyrightPaola Paiero
Twig of Salix cinerea with male catkins.
Male flowersTwig of Salix cinerea with male catkins.Paola Paiero
Twig of Salix cinerea with characteristic large female catkins.
TitleFemale flowers
CaptionTwig of Salix cinerea with characteristic large female catkins.
CopyrightPaola Paiero
Twig of Salix cinerea with characteristic large female catkins.
Female flowersTwig of Salix cinerea with characteristic large female catkins.Paola Paiero

Identity

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Preferred Scientific Name

  • Salix cinerea L.

Preferred Common Name

  • grey sallow

Other Scientific Names

  • Salix acuminata Mill.
  • Salix 'AG'
  • Salix aquatica Sm.
  • Salix 'Aquatica'
  • Salix aurita var. cinerea (L.) Fiori

International Common Names

  • English: European gray willow; gray sallow; gray willow; grey willow; large gray willow; large grey willow; pussy willow; rusty sallow
  • French: saule cendré

Local Common Names

  • Denmark: graa pil; rust pil
  • Germany: Asch Weide; Grau-Weide
  • Italy: salice cenerina; salice cerognolo
  • Netherlands: grauwe wilg
  • Poland: wierzba szara
  • Slovakia: vrba popelavá
  • Slovenia: pepelnatosiva vrba

EPPO code

  • SAXCI (Salix cinerea)

Summary of Invasiveness

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S.cinerea was introduced from its native Eurasia mainly for riverbank stabilization. It is now a serious threat to riparian and wetland environments in New Zealand, southeastern Australia and increasingly in parts of the east and northeast USA, one of the most invasive of several weedy Salix spp. it can spread profusely via seed and stem fragments, one or the other noted as prevalent in different areas, forming monocultures and crowding out native vegetation, and autumn leaf-fall is thought to affect water quality.

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Plantae
  •         Phylum: Spermatophyta
  •             Subphylum: Angiospermae
  •                 Class: Dicotyledonae
  •                     Order: Salicales
  •                         Family: Salicaceae
  •                             Genus: Salix
  •                                 Species: Salix cinerea

Notes on Taxonomy and Nomenclature

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Salix is a large genus of some 300-500 species, sub-divided into several subgenera and numerous sections. Salixcinerea, known as grey sallow or large grey willow, was included by Rechinger (1964) in the section Capreae of subgenus Caprisalix, though other taxonomists have proposed different classifications, and S. cinerea is currently considered to be part of subgenus Vetrix, largely equivalent to the former Caprisalix (shrub willows, sallows and osiers) shrubbier species. Two other subgenera are subgenus Salix (tree willows) and subgenus Chamaetia (dwarf, alpine or arctic willows) (van Kraayenoord et al., 1995). Most species within each subgenera can hybridize if flowering times overlap, and there are also many hybrids, both cultivated such as S. viminalis (S. x calodendron) in its native range (McElroy et al., 1983), and spontaneous hybrids from the native range and where introduced. In Australia for example, hybridisation is being increasingly recognised as commonplace, and several ‘species’ have resulted (Cremer, 1999).

Description

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S. cinerea is typically a large shrub 1-2 m tall, rarely a small tree 7 (-10) m high, generally much branched from the base forming a broad, rounded crown. Bark is dark grey to dark grey-brown, smooth when young becoming fissured with age. Twigs dark reddish-brown, and densely pubescent when young, becoming glabrous when 2 years old. A distinct feature are the long ridges visible on branches when the bark is removed. Leaves very variable, not bitter to the taste, usually obovate, ovate or oblanceolate, 2-7(-9) cm long, (1-)1.5-3.5 cm wide, upper surface dull grey-green and pubescent or dark green and lustrous, covered with soft grey hairs underneath. Separate male and female catkins, each cylindrical, 15-35 mm long, appearing before leaves in March-April. Male flowers with 2 free stamens. Capsule with two valves, up to 10 mm.

Distribution

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It is a Eurasian species, commonly distributed throughout Europe, from the Mediterranean to Scandinavia, and extending eastward to Asia, from Crimea to the Caucasus, from northern Iran to Siberia and north of the Caspian and Aral seas to the Chinese border (Jalas and Suominen, 1976; Skvortsov, 1999).

Distribution Table

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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/RegionDistributionLast ReportedOriginFirst ReportedInvasivePlantedReferenceNotes

Asia

AzerbaijanPresentNative Not invasive Natural USDA-ARS, 2008
ChinaPresentFlora of China Editorial Committee, 2007
-XinjiangPresent Natural Flora of China Editorial Committee, 2007
IndiaPresentPresent based on regional distribution.
-Jammu and KashmirPresent Planted CABI, 2005
KazakhstanPresentNative Not invasive Natural USDA-ARS, 2008
KyrgyzstanPresent Natural CABI, 2005
TurkeyPresentNative Not invasive Natural USDA-ARS, 2008

North America

CanadaPresentIntroducedUSDA-NRCS, 2008
-Nova ScotiaPresentIntroducedUSDA-NRCS, 2008
-OntarioPresentIntroducedUSDA-NRCS, 2008
USAPresentIntroducedUSDA-NRCS, 2008
-AlabamaPresentIntroducedUSDA-NRCS, 2008
-ConnecticutPresentIntroducedUSDA-NRCS, 2008
-DelawarePresentIntroducedUSDA-NRCS, 2008
-GeorgiaPresentIntroducedUSDA-NRCS, 2008
-IllinoisPresentIntroducedUSDA-NRCS, 2008
-IndianaPresentIntroducedUSDA-NRCS, 2008
-KentuckyPresentIntroducedUSDA-NRCS, 2008
-LouisianaPresentIntroducedUSDA-NRCS, 2008
-MainePresentIntroducedUSDA-NRCS, 2008
-MarylandPresentIntroducedUSDA-NRCS, 2008
-MassachusettsPresentIntroducedUSDA-NRCS, 2008
-MichiganPresentIntroducedUSDA-NRCS, 2008
-New JerseyPresentIntroducedUSDA-NRCS, 2008
-New YorkPresentIntroducedUSDA-NRCS, 2008
-North CarolinaPresentIntroducedUSDA-NRCS, 2008
-OhioPresentIntroducedUSDA-NRCS, 2008
-PennsylvaniaPresentIntroducedUSDA-NRCS, 2008
-South CarolinaPresentIntroducedUSDA-NRCS, 2008
-TennesseePresentIntroducedUSDA-NRCS, 2008
-UtahPresentIntroducedUSDA-NRCS, 2008
-VirginiaPresentIntroducedUSDA-NRCS, 2008
-West VirginiaPresentIntroducedUSDA-NRCS, 2008
-WisconsinPresentIntroducedUSDA-NRCS, 2008

Europe

AlbaniaPresentNative Not invasive Natural USDA-ARS, 2008
AndorraPresent Natural CABI, 2005
AustriaPresentNative Not invasive Natural USDA-ARS, 2008
BelarusPresentNative Not invasive Natural USDA-ARS, 2008
BelgiumPresentNative Not invasive Natural USDA-ARS, 2008
Bosnia-HercegovinaPresent Natural CABI, 2005
BulgariaPresentNative Not invasive Natural USDA-ARS, 2008
CroatiaPresent Natural CABI, 2005
Czech RepublicPresent Natural CABI, 2005
Czechoslovakia (former)PresentNative Not invasive Natural USDA-ARS, 2008
DenmarkPresentNative Not invasive Natural USDA-ARS, 2008
EstoniaPresentNative Not invasive Natural USDA-ARS, 2008
FinlandPresentNative Not invasive Natural USDA-ARS, 2008
FrancePresentNative Not invasive Natural USDA-ARS, 2008
-CorsicaPresent Natural CABI, 2005
GermanyPresentNative Not invasive Natural USDA-ARS, 2008
GreecePresentNative Not invasive Natural USDA-ARS, 2008
HungaryPresentNative Not invasive Natural USDA-ARS, 2008
IrelandPresent Natural CABI, 2005
ItalyPresentNative Not invasive Natural USDA-ARS, 2008
LatviaPresentNative Not invasive Natural USDA-ARS, 2008
LiechtensteinPresent Natural CABI, 2005
LithuaniaPresentNative Not invasive Natural USDA-ARS, 2008
LuxembourgPresent Natural CABI, 2005
MacedoniaPresent Natural CABI, 2005
MoldovaPresentNative Not invasive Natural USDA-ARS, 2008
MonacoPresent Natural CABI, 2005
NetherlandsPresentNative Not invasive Natural USDA-ARS, 2008
NorwayPresentNative Not invasive Natural USDA-ARS, 2008
PolandPresentNative Not invasive Natural USDA-ARS, 2008
RomaniaPresentNative Not invasive Natural USDA-ARS, 2008
Russian FederationPresentNative Not invasive Natural USDA-ARS, 2008
-Central RussiaPresentNative Not invasive Natural USDA-ARS, 2008
-Northern RussiaPresentNative Not invasive Natural USDA-ARS, 2008
-Southern RussiaPresentNative Not invasive Natural USDA-ARS, 2008
-Western SiberiaPresentNative Not invasive Natural USDA-ARS, 2008
SerbiaPresent Natural CABI, 2005
SlovakiaPresent Natural CABI, 2005
SloveniaPresent Natural CABI, 2005
SpainLocalisedNative Not invasive Natural USDA-ARS, 2008North-east
SwedenPresentNative Not invasive Natural USDA-ARS, 2008
SwitzerlandPresentNative Not invasive Natural USDA-ARS, 2008
UKLocalisedNative Not invasive Natural USDA-ARS, 2008England
UkrainePresentNative Not invasive Natural USDA-ARS, 2008
Yugoslavia (former)PresentNative Not invasive Natural USDA-ARS, 2008

Oceania

AustraliaLocalisedIntroduced Planted USDA-ARS, 2008Naturalized, almost entirely in the south-east
-New South WalesPresentIntroduced Invasive Royal Botanic Gardens Sydney, 2008
-QueenslandPresent, few occurrencesIntroducedRoyal Botanic Gardens Sydney, 2008
-South AustraliaPresent, few occurrencesIntroducedRoyal Botanic Gardens Sydney, 2008
-TasmaniaPresentIntroducedRoyal Botanic Gardens Sydney, 2008
-VictoriaPresentIntroduced Invasive Royal Botanic Gardens Sydney, 2008
-Western AustraliaPresent, few occurrencesIntroducedRoyal Botanic Gardens Sydney, 2008
New ZealandPresentIntroduced1925 Invasive Planted Owen, 1996; Roy et al., 2005; USDA-ARS, 2008Naturalized weed

History of Introduction and Spread

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It was introduced to New Zealand in 1925 (Owen, 1996), and may have been introduced to Australia and North America around the same time. It had been noted as spreading along riverbanks in eastern USA in the 1990s, but it was only noticed as an invasive species in Massachusetts, USA in 2005, though was assumed to have been present for many decades (USDA Forest Service, 2006), and it is possible that it remains an unidentified invasive elsewhere in the USA or in other countries. S. cinerea is the most seriously invasive Salix species in Australia, and large and rapidly expanding populations occur in Victoria, and this species will probably become a major wetland and riverside weed as it is in New Zealand (CRC Weed Management, 2003). In Australia to date, only a few thousand kilometres of streams have been infested badly, i.e. less than 10% of potential willow habitat, and thus except for some of the S. cinerea infestations it is still possible and worthwhile to control the willows in Australia (Cremer, 2003).

Risk of Introduction

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It is listed on the New Zealand National Plant Pest Accord (Roy et al., 2005), on the the USA Mid-Atlantic EPPC list, and is declared an Australian Weed of National Significance (Thorp and Lynch, 2000) and is the most invasive Salix spp. in Australia, being invasive in New South Wales and Victoria, and potentially invasive in South Australia, Queensland and Tasmania. It could become invasive in similar climates in South America is introduced there, and all exotic Salix species should monitored for invasive behaviour wherever present.

Habitat

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Willows in their native ranges occur in permanently or seasonally wet, inundated or waterlogged sites, and S. cinerea in the UK is found in fenland, carrs and occasionally in damp woods especially as sunny edges. Unlike other Salix spp., however, S. cinerea is the only one recorded to invade non-riparian habitats such as wetlands and drainage lines, and is found invading swamps, riverbanks and also wet areas behind coastal dunes. It may also become dominant in swampy areas in New Zealand (Roy et al., 2005). Harman (2004) noted that both subspecies, ssp. cinerea and, to a much lesser extent, ssp. oleifolia, are found in swamps, riverbanks, and other wet areas, and Cremer (2003) noted it as invasive in riparian habits, brackish wetlands on coastlands, wet forests, alpine bogs, disturbed and undisturbed lands.

Habitat List

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CategorySub-CategoryHabitatPresenceStatus
Terrestrial
Terrestrial ‑ Natural / Semi-naturalRiverbanks Principal habitat Harmful (pest or invasive)
Riverbanks Principal habitat Natural
Wetlands Secondary/tolerated habitat Harmful (pest or invasive)
Wetlands Secondary/tolerated habitat Natural
Littoral
Coastal areas Secondary/tolerated habitat Harmful (pest or invasive)
Coastal dunes Secondary/tolerated habitat Harmful (pest or invasive)

Biology and Ecology

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Genetics

S. cinerea is able to hybridize with other members of subgenus Vetrix.

Reproductive Biology

S. cinerea
is a dioecious species, and both male and female flowers are highly attractive to bees, and as such considered to be commonly pollinated by insects such as the introduced European bee (Apis spp.) or native bees (Cremer, 1999) though maybe partly pollinated by wind. Flowering and the production of viable seed may begin from 2-3 years old. Ripe fruits open when dry, and the movement of cottony hairs levers seed out, accelerated by wind. Seed will germinate on and under water and tiny seedlings can survive under water for up to a month but cannot grow until exposed to air (Cremer, 2003).
 
Physiology and Phenology
 
All willows in Australia generally flower in September and October, with fruit maturing a month later (CRC Weed Management, 2003), and S. cinerea as with most other willows will tolerates waterlogging and can sucker. It cannot grow in the shade. It can tolerate strong winds but not maritime exposure. Seedlings grow quickly even in exposed conditions and it provides good shelter for the establishment of woodland plants thus making a good pioneer species and, except in wetter soils it will eventually be out-competed by the other woodland trees.
 
Environmental Requirements

S. cinerea is a temperate species and can tolerate hard and persistent frost. Being a riparian species, it can also tolerate a wide variety of rainfall regimes as long as the soil in which is grows is permanently moist or wet. S. cinerea can grow on light (sandy), medium (loamy) and heavy (clay) soils and even heavy clay soil as long as they are regularly moist or wet soil. It can tolerate permanent water logging and poor aeration, and prefers acid and neutral soils with a pH down to 3.5, making it an extremely hardy species (Cremer, 2003).

Climate

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ClimateStatusDescriptionRemark
C - Temperate/Mesothermal climate Preferred Average temp. of coldest month > 0°C and < 18°C, mean warmest month > 10°C
Cf - Warm temperate climate, wet all year Preferred Warm average temp. > 10°C, Cold average temp. > 0°C, wet all year
Cs - Warm temperate climate with dry summer Preferred Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers
Cw - Warm temperate climate with dry winter Preferred Warm temperate climate with dry winter (Warm average temp. > 10°C, Cold average temp. > 0°C, dry winters)

Latitude/Altitude Ranges

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Latitude North (°N)Latitude South (°S)Altitude Lower (m)Altitude Upper (m)
66-37 0 1200

Air Temperature

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Parameter Lower limit Upper limit
Absolute minimum temperature (ºC) >-30
Mean annual temperature (ºC) 0 15
Mean maximum temperature of hottest month (ºC) 15 23
Mean minimum temperature of coldest month (ºC) -10 5

Rainfall

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ParameterLower limitUpper limitDescription
Dry season duration02number of consecutive months with <40 mm rainfall
Mean annual rainfall5002500mm; lower/upper limits

Notes on Natural Enemies

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Harman (2004) includes a thorough list of insects recorded as attacking Salix spp. and S. cinerea in particular. Also, a list of 76 diseases found on Salix spp. in New Zealand is included in Harman (2004), who noted that only Melampsora epitea was specific, though it was also recorded on S. cinerea × viminalis, and S. reichardtii (pussy willow), a cross that contains S. cinerea. The self-introduced willow sawfly (Nematus oligospilus) damages many different willow species as well as poplars in New Zealand, with the host range being wider than was first anticipated (Harman, 2004). S. cinerea does not appear, however, to be suppressed by natural enemies in New Zealand, although an extensive number of invertebrates and diseases have been recorded from Salixspecies in the Northern Hemisphere. Some of these are highly damaging pests of commercially grown species such as S. viminalis, suggesting potential for reducing vigour and reproduction of S. cinerea.

Means of Movement and Dispersal

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Natural Dispersal (Non-Biotic)


Willows reproduce either by seed or vegetatively, typically by broken branches taking root. Both sexes of S. cinerea occur in New Zealand and reproduction is almost exclusively by seed that is capable of very wide dispersal, and the prolific production of light wind dispersed seed is probably an important factor in the invasiveness of this species (Harman, 2004). S. cinerea seed will float on water while it remains attached to its cotton parachute, though that soon falls off unless the water is very still, but it is possible for seedlings to be transported by flooding up to 100 km (Cremer, 1999, 2003). The very light seeds can travel some distance in the wind and it can thus invade areas such as cleared woodland where the soil has been disturbed. However, in Australia, spread of S. cinerea is considered to be mostly by stem sections spreading downstream (Cremer, 2003).
 
Intentional Introduction

Long distance dispersal has been due to intentional introduction and planting, largely for riverbank erosion control, and it continues to be promoted as such.

Impact Summary

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CategoryImpact
Economic/livelihood Negative
Environment (generally) Positive and negative

Impact

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Economic Impact

The cost of willow management is about $2 million per year in Victoria, Australia alone, and control costs in New South Wales and New Zealand may also be expected to be equally high. However, Salix spp. play a vital role in flood prevention and erosion control, and there are no known suitable alternatives (Harman, 2004).
 
Environmental Impact

In Australia, the spread of S. cinerea has negative effects on biodiversity and stream morphology via impacts on stream hydrology, stream ecology and riparian ecology, and Cremer (2003) and others have detailed the environmental imapcts. This includes impacts on: river geomorphology, river dynamics, the pool-riffle sequence, frequency of flooding, rates of bank erosion, physio-chemical properties of water, in-stream habitat quality, nutrient input, displacing native vegetation such as native Eucalyptus spp., and affecting faunal food and habitat quality. S. cinerea obstructs and diverts streamflow due to thicket establishment on banks and invasion of shallow water by branches falling into the water and rooting. S. cinerea also produce dense shade during the growing season eliminating many native terrestrial plants growing beneath and possibly decrease water temperature, and leaf-fall may reduce oxygen content.

However, in contrast to these negative impacts, willows do have a positive impact, for example, providing stream stabilisation as well as food and habitat for native animals where native vegetation is absent.

Risk and Impact Factors

Top of page Invasiveness
  • Proved invasive outside its native range
  • Has a broad native range
  • Abundant in its native range
  • Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
  • Pioneering in disturbed areas
  • Highly mobile locally
  • Fast growing
  • Has high reproductive potential
  • Reproduces asexually
  • Has high genetic variability
Impact outcomes
  • Ecosystem change/ habitat alteration
  • Modification of hydrology
  • Modification of nutrient regime
  • Modification of successional patterns
  • Monoculture formation
  • Reduced native biodiversity
  • Threat to/ loss of endangered species
  • Threat to/ loss of native species
Impact mechanisms
  • Competition - monopolizing resources
  • Competition - shading
  • Rapid growth
Likelihood of entry/control
  • Difficult to identify/detect in the field
  • Difficult/costly to control

Uses

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All Salix spp. have been used extensively for riverbank protection and soil stabilisation, also in shelterbelts, and some have ornamental value, and apparently there are no alternative to willows for flood protection (Harman, 2004). Fresh bark of all Salix spp. contains salicin, which decomposes into salicylic acid, closely related to aspirin. Bark is removed in the summer and dried for later use, taken internally for treating rheumatism, arthritis, gout, inflammatory stages of auto-immune diseases, diarrhoea, dysentery, feverish illnesses, neuralgia and headache. Fresh or dry leaves are used internally to treat minor fevers and colic.

Similarities to Other Species/Conditions

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S. cinerea may be confused with any number of similar Salix spp., many of which may be invasive in the same areas. Striations under the bark of twigs is often given as one of better distinguishing features, though numerous keys and field guides exist. However, expert advice could be sought to positively identify the Salix species present, as spontaneous hybrids are known to occur. To further complicate an already complicated taxonomy in the introduced range, it may involve species that do not have sympatric ranges in their native range.

References

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Adair R; Sagliocco JL; Bruzzese E, 2006. Strategies for the biological control of invasive willows (Salix spp.) in Australia. Australian Journal of Entomology, 45(4):259-267. http://www.blackwell-synergy.com/servlet/useragent?func=showIssues&code=aen

CABI, 2005. Forestry Compendium. Wallingford, UK: CABI.

Christensen KI; Nielsen H, 1992. Rusty sallow (Salix cinerea subsp. oleifolia) - an overlooked sallow in Denmark and Scandinavia. [Rust-pil (Salix cinerea subsp. oleifolia) - en overset pil i Danmark og Skandinavien.] Dansk Dendrologisk Arsskrift, 10: 5-17; 13 ref.

Cremer K; Gooey M; Houghton P, 1999. Willow management for Australian rivers. Natural Resource Management, Special Issue, December. 26 pp.

Cremer K; Kraayenoord CV; Parker N; Streatfield S, 1995. Willows spreading by seed - implications for Australian river management. Australian Journal of Soil and Water Conservation, 8(4):18-27; 25 ref.

Cremer KW, 2003. Introduced willows can become invasive pests in Australia. Biodiversity, 4(4):17-24.

Farrell B, unda. Strategic Planning for Willow Management in Tasmania. Hobart, Australia: Tasmanian Conservation Trust.

Flora of China Editorial Committee, 2007. Flora of China Web. Cambridge, USA: Harvard University Herbaria. http://flora.huh.harvard.edu/china/

Forest Service USDA, 2006. From obscurity to notoriety: large gray willow. A forest health program success story. USDA Forest Service, Northeastern Area State and Private Forestry. http://www.na.fs.fed.us/ss/06/fh/gray_willow_access.pdf

Harman HM, 2004. Feasibility of biological control of grey willow Salix cinerea. DOC Science Internal Series, 183. Wellington, New Zealand: Department of Conservation, 29 pp. http://www.doc.govt.nz/upload/documents/science-and-technical/dsis183.pdf

Jalas J; Suominen J, 1976. Atlas Florae Europeae. Distribution of vascular plants in Europe. Vol. 3. Salicaceae to Balanophoraceae. Helsinki, Finland.

Kraayenoord CWS van; Slui B; Knowles FB, 1995. Introduced forest trees in New Zealand. Recognition, role, and seed source. 15. The willows. Salix spp. FRI Bulletin, No. 124, pt. 15, 32 pp.; 25 ref.

McElroy GH; Dawson M; Stott KG; Parfitt RI, 1983. Willows biomass as source of fuel. Long Ashton Research Station. University of Bristol, No. 83/7.

Meikle RD, 1984. Willows and poplars of Great Britain and Ireland. London, UK: BSDI.

Muyt A, 2001. Bush invaders of South-East Australia: a guide to the identification and control of environmental weeds found in South-East Australia. Meredith, Australia: R.G. and F.J. Richardson, xvi + 304 pp.

Newsholme C, 1992. Willows: the genus Salix. London, UK: BT Batsford Ltd.

Owen SJ, 1996. Ecological weeds on conservation land in New Zealand: a database. Department of Conservation, Wellington, New Zealand: DOC Science Publications. http://www.hear.org/weedlists/other_areas/nz/nzecoweeds.htm

Patrick KN, 1990. Watermark disease of willows. Arboriculture Research Note - Department of the Environment UK, No. 87:4 pp.

PIER, 2008. Pacific Islands Ecosystems at Risk. USA: Institute of Pacific Islands Forestry. http://www.hear.org/pier/index.html

Rechinger KH, 1964. Salix L. In: Tutin TG, Heywood VH, Burges NA, Valentine DH, Walters SM, Webb DA, eds. Flora Europaea, Volume 1. Cambridge, UK: Cambridge University Press.

Roy B; Popay I; Champion P; James T; Rahman A, 2005. An Illustrated Guide to Common Weeds of New Zealand. Royal New Zealand Institute of Horticulture. http://www.rnzih.org.nz/pages/salixcinerea.htm

Royal Botanic Gardens Sydney, 2008. Australia's Virtual Herbarium. Sydney, Australia: Royal Botanic Gardens. http://avhtas.tmag

Schiechtl HM, 1996. Use of willows: Central European and Mediterranean species, their use and identification. I salici nell'uso pratico: i salici dell'Europa centrale e dell'area centrale del Mediterraneo, il loro impiego, la loro determinazione., 178 pp.; 4 pp. of ref.

Shirnin VK; Gorobets AI, 1992. A late flushing form of Salix cinerea. Lesovedenie, No. 2, 74-77; 21 ref.

Skvortsov AK, 1999. Willows of Russia and adjacent countries. Taxonomical and geographical revision. Report Series No. 39. Joensuu, Finland: Faculty of Mathematics and Natural Sciences, University of Joensuu. 307pp.

Thakur RN, 1995. Botryosphaeria ribis-a causal agent of black stem rot of Salix cinerea. Indian Phytopathology, 48(3):374.

Thorp JR; Lynch R, 2000. The determination of Weeds of National Significance. Launceston, Australia: National Weeds Strategy Executive Committee.

USDA-ARS, 2008. 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, 2008. The PLANTS Database. Baton Rouge, USA: National Plant Data Center. http://plants.usda.gov/

Ward BG; Henzell RF, 2004. Use of herbicidal gels on woody weeds. DOC Science Internal Series, No.162:21 pp.

Weed Management CRC, 2003. Willow - Salix spp. Weed Management Guide. Weeds of National Significance. CRC Weed Management, 6 pp. http://www.weeds.crc.org.au/documents/wmg_willow.pdf

Contributors

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29/02/2008 Updated by:

Nick Pasiecznik, Consultant, France

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