Salix cf. cinerea/atrocinerea
Common Name:
Large gray willow
Synonyms and Other Names:
Salix acuminata Mill., Salix cinerascens Link ex Willd., Salix cinerea L. subsp. atrocinerea (Brot.) Guinier, Salix cinerea L. subsp. catalaunica (Goerz) Maire & Weiller, Salix guinieri Chass. & Goerz, Salix incerta Lapeyr., Salix pleifolia Sm., Salix renecia Dode, Salix rufinervis DC (Barstow et al. 2018).
Identification:
S. atrocinerea is a tree or shrub that can either branch from the base of the plant or form a single trunk (Zinovjev 2010, Rawlins 2015). trunk. Branches spread to form a broad, rounded or flattened crown. Its bark is dark grey brown, which becomes fissured with age. The twigs are dark reddish brown, which are densely pubescent at first and can remain so for the first year before becoming glabrous or subglabrous (Zinovjev 2010, Rawlins 2015). The leaves are shiny on the upper surface, and covered with soft grey hairs underneath (Zinovjev 2010). The leaves of S. cinerea are very varied, usually obovate or broadly oblanceolate, 2-9 cm long and 1-3 cm wide. Catkins appear in advance of the leaves and are cylindrical and 2-3 cm long and 0.6-1 cm wide (GISD 2022). Female catkins are smaller and narrower than the male. The fruit is a capsule with two valves, containing many tiny seeds (Royal New Zealand Institute of Horticulture, 2005, Slimbridge Wetland Plants, Undated, in Global Invasive Species Database 2022). Decorticated wood also shows ridges as early as one year of age (Argus 1986, Kadis and Zinovjez 2021).
Size:
Up to 12m tall (Argus 1986)
Native Range:
Europe, North Africa, Western Asia (Lansdown 2014, Barstow et al. 2018).
Table 1. Great Lakes region nonindigenous occurrences, the earliest and latest observations in each state/province, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Salix cf. cinerea/atrocinerea are found here.
Full list of USGS occurrences
Table last updated 5/2/2024
† Populations may not be currently present.
Ecology:
The species is found in a variety of habitats: Riparian zones, alpine bogs, wetland forests, and brackish wetlands (Cremer 2003, Lansdown 2014). S. atrocinerea prefers waterlogged where it is able to form dense canopies and limit the growth of other native plants (Cremer 2003). The species also tolerates a variety of soil conditions. It grows in anaerobic soils with pH as low as 3.5 but also thrives in basic soils (Iremonger and Kelly 1988, West 1994 in Cremer 2003, Raposo et al. 2020, Rubio-Rios et al. 2022). S. atrocinerea has shown no preference in sediment size and will grow in soils contaminated by heavy metals and arsenic (Alvarez et al. 2003, Cremer 2003, Fresno et al. 2012, Ansola et al. 2014). The species grows quickly and is not shade-tolerant, enabling it to dominate open environments or those affected by wildfire (Cruz et al. 2020). S. atrocinerea is highly fecund and reaches maturity in 2-3 years of life (Cremer 2003). It may reproduce via sexual reproduction faciliated by pollinators or by planting shoots or branches (Vieitez et al. 1967, Armstrong 1968, Vieitez and Peña 1968) These cuttings grow quickly and demonstrate some resistance to allelopathic chemicals released by competitors (Dommanget et al. 2013). Seeds are small and possess wooly parachutes, allowing them to disperse by wind or water, often kilometers from their parent tree (Cremer 2003, Rawlins 2015) Kadis and Zinovjev noted that mature populations of Salix sp. can produce over 15 seedlings per m2 per year (2022). Seedlings germinate quickly, between 4-10 days after planting, but their viability declines precipitously after one or two weeks (Cruz et al. 2020). Cremer reported that viability lasts up to 6 weeks and that seeds will remain viable submerged in water for up to a month (2003).
Great Lakes Means of Introduction:
S. atrocinerea seeds are small and possess fibrous parachutes (Cremer 2003). This allows the seeds to disperse miles away from their parent tree. Seeds will remain viable for weeks and can survive being submerged for a short period of time (Cremer 2003). Therefore, natural dispersal by wind and water is the most likely means of introduction. It is also possible that with their wooly fibers and small size, seedlings could get caught in gear or boot treads.
Great Lakes Status:
Members of this species complex are likely currently established in wetlands below the normal high water mark of the Great Lakes. Citizen scientists have reported sightings of Salix atrocinerea within 20 km of the basin as recently as 2021 but they have not been confirmed (iNaturalist, 2022).
Great Lakes Impacts:
Salix atrocinerea has the potential for high environmental impact if introduced to the Great Lakes. The species possesses a high growth rate and is highly fecund. It can quickly overtake wetlands and riparian zones, reducing populations of native species, especially in the undergrowth as it produces dense shade (Cremer 2003). Cremer also reported that its dense root structure modifies banks, eliminating habitat niches for animals. These dense root structures can also alter the hydrology of riparian zones (Cremer 2003). Furthermore, it creates microhabitats in its vicinity with lower water temperatures and dissolved oxygen concentrations (Cremer 2003). The species is also recognized as a facultative resprouter and will rapidly colonize areas impacted by wildfire (Cruz et al. 2020).
There is little or no evidence to support that Salix atrocinerea has the potential for significant socioeconomic impacts if introduced to the Great Lakes.
Salix atrocinerea has the potential for high beneficial impact if introduced to the Great Lakes.
S. atrocinerea’s beneficial qualities lie in its potential as a phytoremediator. Several studies have demonstrated the species’s potential to bioaccumulate arsenic, cadmium, zinc, iron, lead, and manganese (Alvarez et al. 2003, Moreno Jimenez et al. 2009, Fresno et al. 2012, Navazas et al. 2022). Arroyo et al. 2010 found that the species is able to facilitate the growth of a diverse microbial community and aid in the removal of harmful chemicals in municipal wastewater. Their quick growth and dense root structure also make them ideal candidates to aid in erosion control (Cremer et al. 1995).
Management:
Regulations (pertaining to the Great Lakes region): This species is not on the Illinois Aquatic Life Approved Species List. If it is not otherwise native to Illinois, it is illegal to be imported or possessed alive without a permit. (515 ILCS 5/20-90)
It is prohibited in New York and cannot be knowingly possessed with the intent to sell, import, purchase, transport or introduce nor can any of these actions be taken. (6 NYCRR Part 575)
Note: Check federal, state/provincial, and local regulations for the most up-to-date information.
Control
Biological
In its native range, a variety of invertebrates feed on S. atrocinerea (Harman 2004). These include various species of aphids, scale insects, sawflies, butterflies, and moths. Harman noted that sawflies in particular have narrow diets but was uncertain about the effects of releasing these organisms in New Zealand. The following pathogens were found to target S. atrocinerea: Melampsora larici-epitea, Erwinia salicis, Melasmia salicina (Rhytisma salicinum), Botryosphaeria ribis black stem-rotting disease (Patrick 1990, Abseitova 1993, Thakur 1995, Pei et al. 2002, in Harman 2004). However, these pathogens target species besides S. atrocinerea, rendering them unsuitable for use.
Physical
The following physical methods are known to be effective in controlling S. atrocinerea populations when enacted in conjunction with herbicides. They are: cutting the tree and injecting the remaining stump with herbicide, partially cutting into the tree and applying herbicide, removing the bark of an individual and injecting the wood with herbicide, and boring into an individual and filling the hole with herbicide (Weedbusters 2022).
Chemical
The following chemicals and concentrations are effective in controlling the species: glyphosate (10 mL undiluted) metsulfuron-methyl (600g/kg), and picloram (concentration unknown) (Weedbusters 2022).
References
(click for full reference list)
Author:
I. Pfingsten and D. Rose.
Contributing Agencies:
Revision Date:
1/19/2024
Citation for this information:
I. Pfingsten and D. Rose., 2024, Salix cf. cinerea/atrocinerea: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI, https://nas.er.usgs.gov/queries/greatLakes/FactSheet.aspx?Species_ID=3814&Potential=N&Type=0&HUCNumber=DGreatLakes, Revision Date: 1/19/2024, Access Date: 5/2/2024
This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.