Salix × fragilis is a medium-sized to large deciduoustree, which grows rapidly to 10–20 m (33–66 ft) (rarely to 29 m (95 ft)) tall, with a trunk up to 1 m (3.3 ft) diameter, often multi-trunked, and an irregular, often leaning crown. The bark is dark grey-brown, coarsely fissured in older trees. The lanceolateleaves are bright green, 9–15 cm long and 1.5–3 cm wide, with a finely serrated margin; they are very finely hairy at first in spring, but soon become hairless.[4]
The flowers are produced in catkins in early spring, and pollinated by insects. They are dioecious, with male and female catkins on separate trees; the male catkins are 4–6 cm long, the female catkins are also 4–6 cm long, with the individual flowers having either one or two nectaries.[2][3][6] In late spring fruit capsules release numerous small cotton-tufted seeds. They are easily distributed by wind and moving water, and germinate immediately after soil contact.[4]
Taxonomy
Carl Linnaeus first described a willow species as "Salix fragilis" in 1753.[7] It was later discovered that Linnaeus was actually describing a species he had also called Salix pentandra. At least since the 1920s, botanists applied Linnaeus's name "Salix fragilis" both to a pure species and to its hybrid with Salix alba.[8][9][10] In 2005, it was proposed that "Salix fragilis" should be conserved for the pure species, with the hybrid called "Salix × rubens". The alternative was to conserve "Salix fragilis" for the hybrid, with the pure species requiring a new name.[10] After discussion, the decision was made by the Nomenclature Committee for Vascular Plants in 2009 to reject the first proposal and conserve "Salix fragilis" for the hybrid.[11] Irina V. Belyaeva then described the previously unnamed parent species as Salix euxina,[8][9][12] and designated a lectotype for the hybrid.[8] The lectotype was shown by molecular evidence to be the hybrid between S. alba and S. euxina,[9] the name of which is written as Salix × fragilis to show its hybrid status.[1][9]
Varieties
S. × fragilis is very variable, with forms linking both parents. Some formally named varieties include the following.[1][5] As of August 2021[update], none were accepted at this rank by Plants of the World Online, being treated as synonyms of the species.[1]Clive A. Stace suggested some would be better treated as cultivars.[5]
S. × fragilis var. decipiens W.D.J.Koch (S. × decipiens Hoffm.) – assigned to S. × fragilis by Plants of the World Online[1] and by Belyaeva,[8] but to S.euxina by Stace[5]
S. × fragilis var. furcata Ser. ex Gaudin – male tree with relatively wide leaves; of cultivated origin[5]
S. × fragilis var. fragilis – male and female trees known; leaves with even, well spaced teeth[5]
S. × fragilis var. glauca Spenn.
S. × fragilis var. polyandra Wimm.
S. × fragilis var. rubens (Schrank) P.D.Sell
S. × fragilis var. russelliana (Sm.) W.D.J.Koch – Bedford willow; female tree with long narrow leaves having somewhat uneven teeth; of cultivated origin[5]
Ecology
The plant is commonly called crack willow or brittle willow because it is highly susceptible to wind, ice and snow damage.[4] The name also derives from the twigs which break off very easily and cleanly at the base with an audible crack. Broken twigs and branches can take root readily, enabling the species to colonise new areas as broken twigs fall into waterways and can be carried some distance downstream. It is particularly adept at colonising new riverside sandbanks formed after floods. It also spreads by root suckers, expanding into pure 'groves'.[4]
Cultivation
Salix × fragilis is cultivated as a fast-growing ornamental tree. The cultivar 'Russelliana' (syn. S. × fragilis var. russelliana) is by far the most common clone of crack willow in Great Britain and Ireland, very easily propagated by cuttings. It is a vigorous tree commonly reaching 20–25 m (66–82 ft) tall, with leaves up to 15 cm long. It is a female clone.[2]
Invasive species
Salix × fragilis has escaped cultivation to become an invasive species in various parts of the world,[13] including: all states and territories in Australia,[14]New Zealand; the upper half of the United States;[4][15] and South Africa.[16] In New Zealand it is listed on the National Pest Plant Accord, which means it cannot be sold or distributed. It can replace a habitat's native plant species diversity by forming monospecific stands.[17] As only the male plant is present in New Zealand no fruit is formed unless hybridised.[18] Species spread is facilitated by stem fragmentation which are carried via waterways. Control and management for habitat restoration projects often uses herbicides.[4][17][19]
References
^ abcdef"Salix × fragilis L.". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 2021-08-07.
^ abcMeikle, R. D. (1984). Willows and Poplars of Great Britain and Ireland. BSBI Handbook No. 4. ISBN0-901158-07-0.
^ abRushforth, K. (1999). Trees of Britain and Europe. Collins ISBN0-00-220013-9.
^ abcdefgUSFS—United States Forest Service: Salix fragilis — "Weed of the Week" . accessed 1.13.2013
^ abcdefgStace, Clive A. (2019). "S. × fragilis". New Flora of the British Isles (4th ed.). Middlewood Green, Suffolk: C & M Floristics. p. 348. ISBN978-1-5272-2630-2.
^Bean, W. J. (1980). Trees and Shrubs Hardy in the British Isles 8th ed., vol. 4. John Murray ISBN0-7195-2428-8.
^ abcdBelyaeva, Irina (2009). "Nomenclature of Salix fragilis L. and a new species, S. euxina (Salicaceae)". Taxon. 58 (4): 1344–1348. doi:10.1002/tax.584021.
^ abcdKuzovkina, Yulia A. & Belyaeva, Irina V. (July 2018). Name change alert: Salix × fragilis L.(PDF). Fact Sheet No 2. University of Connecticut. Retrieved 2021-08-07.
^ abChristensen, Knud I. & Jonsell, Bengt (2005). "(1698) Proposal to conserve the name Salix fragilis with a conserved type (Salicaceae)". Taxon. 54 (2): 555–556. doi:10.2307/25065400. JSTOR 25065400.
^Brummitt, R.K. (2009). "Report of the Nomenclature Committee for Vascular Plants: 60". Taxon. 58 (1): 280–292. doi:10.1002/tax.581028. JSTOR 27756843.
salix, fragilis, crack, willow, redirects, here, eastern, crack, willow, salix, euxina, with, common, names, crack, willow, brittle, willow, hybrid, species, willow, native, europe, western, asia, native, riparian, habitats, usually, found, growing, beside, ri. Crack willow redirects here For Eastern crack willow see Salix euxina Salix fragilis with the common names crack willow and brittle willow is a hybrid species of willow native to Europe and Western Asia It is native to riparian habitats usually found growing beside rivers and streams and in marshes and water meadow channels 2 3 4 It is a hybrid between Salix euxina and Salix alba and is very variable with forms linking both parents 5 Salix fragilisLeavesScientific classificationKingdom PlantaeClade TracheophytesClade AngiospermsClade EudicotsClade RosidsOrder MalpighialesFamily SalicaceaeGenus SalixSpecies S fragilisBinomial nameSalix fragilisL 1 Synonyms 1 Oisodix decipiens Raf Psatherips fragilis L Raf Salix alba var elyensis Burtt DavySalix chlorocarpa SchurSalix decipiens Hoffm Salix excelsa Tausch ex W D J KochSalix excelsior HostSalix fragilior HostSalix fragilissima HostSalix fragillima SchurSalix gracilenta TauschSalix lyonii J ForbesSalix monspeliensis J ForbesSalix montana J ForbesSalix neotricha GoerzSalix palustris HostSalix pendula Ser Salix persicifolia Schleich Salix rubens SchrankSalix russelliana Sm Salix sanguinea Tausch ex OpizSalix viridis Fr Salix wargiana Lej Vimen russeliana Sm Raf In riparian habitat Hesse Germany Contents 1 Description 2 Taxonomy 2 1 Varieties 3 Ecology 4 Cultivation 5 Invasive species 6 References 7 External linksDescription EditSalix fragilis is a medium sized to large deciduous tree which grows rapidly to 10 20 m 33 66 ft rarely to 29 m 95 ft tall with a trunk up to 1 m 3 3 ft diameter often multi trunked and an irregular often leaning crown The bark is dark grey brown coarsely fissured in older trees The lanceolate leaves are bright green 9 15 cm long and 1 5 3 cm wide with a finely serrated margin they are very finely hairy at first in spring but soon become hairless 4 The flowers are produced in catkins in early spring and pollinated by insects They are dioecious with male and female catkins on separate trees the male catkins are 4 6 cm long the female catkins are also 4 6 cm long with the individual flowers having either one or two nectaries 2 3 6 In late spring fruit capsules release numerous small cotton tufted seeds They are easily distributed by wind and moving water and germinate immediately after soil contact 4 Taxonomy EditCarl Linnaeus first described a willow species as Salix fragilis in 1753 7 It was later discovered that Linnaeus was actually describing a species he had also called Salix pentandra At least since the 1920s botanists applied Linnaeus s name Salix fragilis both to a pure species and to its hybrid with Salix alba 8 9 10 In 2005 it was proposed that Salix fragilis should be conserved for the pure species with the hybrid called Salix rubens The alternative was to conserve Salix fragilis for the hybrid with the pure species requiring a new name 10 After discussion the decision was made by the Nomenclature Committee for Vascular Plants in 2009 to reject the first proposal and conserve Salix fragilis for the hybrid 11 Irina V Belyaeva then described the previously unnamed parent species as Salix euxina 8 9 12 and designated a lectotype for the hybrid 8 The lectotype was shown by molecular evidence to be the hybrid between S alba and S euxina 9 the name of which is written as Salix fragilis to show its hybrid status 1 9 Varieties Edit S fragilis is very variable with forms linking both parents Some formally named varieties include the following 1 5 As of August 2021 update none were accepted at this rank by Plants of the World Online being treated as synonyms of the species 1 Clive A Stace suggested some would be better treated as cultivars 5 S fragilis var decipiens W D J Koch S decipiens Hoffm assigned to S fragilis by Plants of the World Online 1 and by Belyaeva 8 but to S euxina by Stace 5 S fragilis var furcata Ser ex Gaudin male tree with relatively wide leaves of cultivated origin 5 S fragilis var fragilis male and female trees known leaves with even well spaced teeth 5 S fragilis var glauca Spenn S fragilis var polyandra Wimm S fragilis var rubens Schrank P D Sell S fragilis var russelliana Sm W D J Koch Bedford willow female tree with long narrow leaves having somewhat uneven teeth of cultivated origin 5 Ecology EditThe plant is commonly called crack willow or brittle willow because it is highly susceptible to wind ice and snow damage 4 The name also derives from the twigs which break off very easily and cleanly at the base with an audible crack Broken twigs and branches can take root readily enabling the species to colonise new areas as broken twigs fall into waterways and can be carried some distance downstream It is particularly adept at colonising new riverside sandbanks formed after floods It also spreads by root suckers expanding into pure groves 4 Cultivation EditSalix fragilis is cultivated as a fast growing ornamental tree The cultivar Russelliana syn S fragilis var russelliana is by far the most common clone of crack willow in Great Britain and Ireland very easily propagated by cuttings It is a vigorous tree commonly reaching 20 25 m 66 82 ft tall with leaves up to 15 cm long It is a female clone 2 Invasive species EditSalix fragilis has escaped cultivation to become an invasive species in various parts of the world 13 including all states and territories in Australia 14 New Zealand the upper half of the United States 4 15 and South Africa 16 In New Zealand it is listed on the National Pest Plant Accord which means it cannot be sold or distributed It can replace a habitat s native plant species diversity by forming monospecific stands 17 As only the male plant is present in New Zealand no fruit is formed unless hybridised 18 Species spread is facilitated by stem fragmentation which are carried via waterways Control and management for habitat restoration projects often uses herbicides 4 17 19 References Edit a b c d e f Salix fragilis L Plants of the World Online Royal Botanic Gardens Kew Retrieved 2021 08 07 a b c Meikle R D 1984 Willows and Poplars of Great Britain and Ireland BSBI Handbook No 4 ISBN 0 901158 07 0 a b Rushforth K 1999 Trees of Britain and Europe Collins ISBN 0 00 220013 9 a b c d e f g USFS United States Forest Service Salix fragilis Weed of the Week accessed 1 13 2013 a b c d e f g Stace Clive A 2019 S fragilis New Flora of the British Isles 4th ed Middlewood Green Suffolk C amp M Floristics p 348 ISBN 978 1 5272 2630 2 Bean W J 1980 Trees and Shrubs Hardy in the British Isles 8th ed vol 4 John Murray ISBN 0 7195 2428 8 Salix fragilis L The International Plant Names Index Retrieved 2021 08 07 a b c d Belyaeva Irina 2009 Nomenclature of Salix fragilis L and a new species S euxina Salicaceae Taxon 58 4 1344 1348 doi 10 1002 tax 584021 a b c d Kuzovkina Yulia A amp Belyaeva Irina V July 2018 Name change alert Salix fragilisL PDF Fact Sheet No 2 University of Connecticut Retrieved 2021 08 07 a b Christensen Knud I amp Jonsell Bengt 2005 1698 Proposal to conserve the name Salix fragilis with a conserved type Salicaceae Taxon 54 2 555 556 doi 10 2307 25065400 JSTOR 25065400 Brummitt R K 2009 Report of the Nomenclature Committee for Vascular Plants 60 Taxon 58 1 280 292 doi 10 1002 tax 581028 JSTOR 27756843 Salix euxina I V Belyaeva The International Plant Names Index retrieved 2021 08 07 Invasive org Salix fragilis crack willow accessed 1 13 2013 Salix fragilis U S states with invasive S fragilis sites include CN CO ID IL IN IO MA MI MN MO NB ND NJ OH OR NH NM NV NY PA RI SD UT VA VT WA WI WV and WY USFS amp invasive org Plant an indigenous garden a b Griffiths J Armstrong H Innes R Terry J January 2018 Can aerial herbicide application control Grey Willow Salix cinerea L and stimulate native plant recovery in New Zealand wetlands Ecological Management amp Restoration 19 1 49 57 doi 10 1111 emr 12299 ISSN 1442 7001 Crack willow MPI Biosecurity New Zealand Archived from the original on 2016 04 14 Retrieved 2013 04 22 Griffiths James McAlpine Kate 2017 Aerial glyphosate application reduces grey willow Salix cinerea canopy cover increases light availability and stimulates kahikatea Dacrycarpus dacrydioides growth New Zealand Journal of Ecology 41 2 doi 10 20417 nzjecol 41 22 External links Edit Wikimedia Commons has media related to Salix fragilis Wikispecies has information related to Salix fragilis USFS United States Forest Service Salix fragilis Weed of the Week Center for Invasive Species and Ecosystem Health Invasive org photos gallery Salix fragilis Plants for a Future Retrieved from https en wikipedia org w index php title Salix fragilis amp oldid 1105609210, wikipedia, wiki, book, books, library,
