Reference List

This list includes references used to derive specimen records as well as those with scientific name Crassula helmsii listed in key words.

Results also available in (click to export table to spreadsheet)

REFTypeCut-and-Paste Reference
45533 Journal Article Bok, M.W.J., J.M.M. van der Loop, H.H. van Kleef, and R.S.E.W. Leuven. 2025. Fragment viability, regenerative capacity and protoplast isolation of invasive Australian swamp stonecrop (Crassula helmsii). Aquatic Botany 196:103835. https://doi.org/10.1016/j.aquabot.2024.103835.
38192 Journal Article Bradbeer, S. J., T. Renals, C. Quinn, D. A. Warren, B. Pile, K. Hills, and A. Dunn. 2021. The effectiveness of hot water pressurized spray in field conditions to slow the spread of invasive alien species. Management of Biological Invasions 12(1):125-147. https://www.reabic.net/journals/mbi/2021/1/MBI_2021_Bradbeer_etal.pdf.
37131 Journal Article Bradbeer, S.J., T. Renals, C. Quinn, D.A. Warren, B. Pile, K. Hills, and A.M. Dunn. 2021. The effectiveness of hot water pressurized spray in field conditions to slow the spread of invasive alien species. Management of Biological Invasions 12(1):1. https://doi.org/10.3391/mbi.2021.12.1.09.
29339 Journal Article Bridge, T. 2005. Controlling New Zealand pygmyweed Crassula helmsi using hot foam, herbicide and by burying at Old Moor RSPB Reserve, South Yorkshire, England. Conservation Evidence 2:33-34. http://www.conservationevidence.com/individual-study/2146.
29479 Report Brunet, J. 2002. Effect of chemical and physical environment on Crassula helmsii spread. Centre for Ecology & Hydrology, Natural Environment Research Council, Dorset, UK. http://nora.nerc.ac.uk/18652/1/N018652RE.pdf.
39644 Journal Article Callaghan, D.A. 2021. Population status and ecology of Micromitrium tenerum Austin in England. Journal of Bryology 43(3):234-241. https://doi.org/10.1080/03736687.2021.1910436.
39651 Journal Article Callaghan, D.A., R. Medina, J. Masson, and H. During. 2020. Population status and ecology of the episodic moss Physcomitrium eurystomum Sendtn. in Britain. Journal of Bryology 42(3):246-257. https://doi.org/10.1080/03736687.2020.1743562.
39674 Journal Article Coughlan, N.E., F. Armstrong, C. Baker-Arney, K. Crane, R.N. Cuthbert, M.A.K. Jansen, L. Kregting, G.Y.W. Vong, and J.T.A. Dick. 2022. Retention of viability by fragmented invasive Crassula helmsii, Elodea canadensis and Lagarosiphon major. River Research and Applications Special Issue:1-6. https://doi.org/10.1002/rra.3952.
39678 Journal Article Crane, K., R.N. Cuthbert, A. Ricciardi, L. Kregting, N.E. Coughlan, H.J. MacIsaac, N. Reid, and J.T.A. Dick. 2021. Gimme shelter: differential utilisation and propagule creation of invasive macrophytes by native caddisfly larvae. Biological Invasions 23(1):95-109. https://doi.org/10.1007/s10530-020-02358-7.
39675 Journal Article Crane, K., R.N. Cuthbert, E.M. Cunningham, S.J. Bradbeer, L. Eagling, L. Kregting, J.T.A. Dick, A.M. Dunn, E.R.C. Smith, C. Shannon, J.M. Caffrey, F.E. Lucy, E. Davis, and N.E. Coughlan. 2020. Tomorrow never dies: biodegradation and subsequent viability of invasive macrophytes following exposure to aquatic disinfectants. Management of Biological Invasions 11(1):26-43. https://doi.org/10.3391/mbi.2020.11.1.03.
39677 Journal Article Crane, K., R.N. Cuthbert, J.T.A. Dick, L. Kregting, H.J. MacIsaac, and N.E. Coughlan. 2019. Full steam ahead: direct steam exposure to inhibit spread of invasive aquatic macrophytes. Biological Invasions 21(4):1311-1321. https://doi.org/10.1007/s10530-018-1901-2.
29341 Journal Article Dawson, F. 1996. Crassula helmsii: attempts at elimination using herbicides. Hydrobiologia 340(1):241. https://doi.org/10.1007/BF00012762.
29340 Journal Article Dawson, F.H., and E.A. Warman. 1987. Crassula helmsii (T. Kirk) Cockayne: Is it an aggressive alien aquatic plant in Britain? Biological Conservation 42(4):247-272. https://doi.org/10.1016/0006-3207(87)90071-1.
29357 Journal Article European and Mediterranean Plant Protection Organization (EPPO). 2007. Crassula helmsii. European and Mediterranean Plant Protection Organization Bulletin 37:225-229. https://www.eppo.int/QUARANTINE/data_sheets/plants/Crassula_helmsii_DS.pdf.
29351 Journal Article European and Mediterranean Plant Protection Organization (EPPO). 2014. PM 9/19 (1) Invasive alien aquatic plants. European and Mediterranean Plant Protection Organization Bulletin 44(3):457-471. https://doi.org/10.1111/epp.12165.
39943 Report Ewald, N.C. 2014. Crassula helmsii in the New Forest
Final report on the status, spread and impact of this non-native invasive plant, and the efficacy of control techniques following a 3-year trial. Freshwater Habitats Trust, Oxford, England. https://www.hiwwt.org.uk/sites/default/files/2018-06/Final%20report%20by%20Dr%20Naomi%20Ewald%20%28control%20of%20New%20Zealand%20Pygmyweed%29.pdf.
45108 Journal Article Fagundez, J., M.A. Fernandez, A. Balado, E. Martinez-Veiga, and M.J. Servia. 2024. First record of the semi-aquatic invasive plant Crassula helmsii in the Iberian Peninsula and its link to potential dispersal drivers. Biological Invasions 26:1997-2004. https://link.springer.com/article/10.1007/s10530-024-03300-x.
29342 Journal Article Gassmann, A., M.J.W. Cock, R. Shaw, and H.C. Evans. 2006. The potential for biological control of invasive alien aquatic weeds in Europe: a review. Hydrobiologia 570(1):217-222. https://doi.org/10.1007/s10750-006-0182-4.
39679 Journal Article Giordano, S. 2022. Ecological impacts of the non-native Macrophyte Crassula helmsii on freshwater macroinvertebrate assemblages in Dartmoor National Park, UK. The Plymouth Student Scientist 15(1):23-47. https://doi.org/10.24382/heqn-hr61.
29343 Journal Article Hussner, A., I. Stiers, M.J.J.M. Verhofstad, E.S. Bakker, B.M.C. Grutters, J. Haury, J.L.C.H. van Valkenburg, G. Brundu, J. Newman, J.S. Clayton, L.W.J. Anderson, and D. Hofstra. 2016. Management and control methods of invasive alien freshwater aquatic plants: a review. Aquatic Botany 136:112-137. https://doi.org/10.1016/j.aquabot.2016.08.002.
29480 Journal Article Kirby, J.E. 1965. Notes on Crassula helmsii. The Cactus and Succulent Journal of Great Britain 27(1):9-10. https://www.cactuspro.com/biblio/en:csjgb.
29481 Journal Article Klavsen, S.K., and S.C. Maberly. 2009. Crassulacean acid metabolism contributes significantly to the in situ carbon budget in a population of the invasive aquatic macrophyte Crassula helmsii. Freshwater Biology 54(1):105-118. https://doi.org/10.1111/j.1365-2427.2008.02095.x/full.
39681 Journal Article Knihinicki, D.K., R. Petanović, T. Cvković, and S. Varia. 2018. A new species of Aculus mite (Acari: Eriophyidae), a potential biocontrol agent for Australian swamp stonecrop, Crassula helmsii (Crassulaceae). Zootaxa 4497(4):573-585. https://doi.org/10.11646/zootaxa.4497.4.7.
29482 Journal Article Langdon, S.J., R.H. Marrs, C.A. Hosie, H.A. McAllister, K.M. Norris, and J.A. Potter. 2004. Crassula helmsii in U.K. Ponds: Effects on plant biodiversity and implications for newt conservation. Weed Technology 18:1349-1352. http://www.jstor.org.proxy.lib.umich.edu/stable/3989649?pq-origsite=summon&seq=1#page_scan_tab_contents.
29352 Database Minchin, D. 2008. Species factsheet: Crassula helmsii. Delivering Alien Invasive Species inventories for Europe (DAISIE). http://www.europe-aliens.org/speciesFactsheet.do?speciesId=8738. Accessed on 01/19/2017.
39683 Journal Article Remigio, A.C., M. Edraki, A.J.M. Baker, and A. van der Ent. 2021. Is the aquatic macrophyte Crassula helmsii a genuine copper hyperaccumulator? Plant and Soil 464(1-2):359-374. https://doi.org/10.1007/s11104-021-04955-4.
38189 Journal Article Reynolds, S.A. and D. C. Aldridge. 2021. Embracing the Allelopathic Potential of Invasive Aquatic Plants to Manipulate Freshwater Ecosystems. Frontiers in Environmental Science 8:551803. https://www.frontiersin.org/articles/10.3389/fenvs.2020.551803/full.
29344 Report Robert, H., R. Lafontaine, R.C. Beudels-Jamar, and T. Delsinne. 2013. Risk analysis of the Australian swamp stonecrop Crassula helmsii (Kirk) Cockayne. Royal Belgian Institute of Natural Sciences. https://www.researchgate.net/publication/266617673_Risk_analysis_of_the_Australian_swamp_stonecrop_Crassula_helmsii_Kirk_Cockayne_-_Risk_analysis_report_of_non-native_organisms_in_Belgium_from_the_Royal_Belgian_Institute_of_Natural_Sciences_for_the_Fe.
29345 Report Smith, C., and E. Harris. 2008. Lound lakes - Botanical survey. Norfolk Wildlife Services. http://www.norfolkbiodiversity.org/pdf/biodiversitysurveys/Lound%20lakes%20aquatic%20plant%20survey%20summary.pdf.
39685 Journal Article Smith, T. and P. Buckley. 2020. Biological Flora of the British Isles: Crassula helmsii. Journal of Ecology 108(2):797-813. https://doi.org/10.1111/1365-2745.13336.
39687 Thesis or Dissertation Strong, C. 2020. Effective management of the invasive aquatic plant Australian swamp stonecrop (Crassula helmsii) in wetlands. Unpublished Ph.D. dissertation. University of Brighton, Brighton, United Kingdom. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.837841 https://lens.org/155-275-354-677-232.
29473 Journal Article Swale, E., and H. Belcher. 1982. Crassula helmsii, the swamp stonecrop, near Cambridge. Nature in Cambridgeshire 25:59-62. http://www.natureincambridgeshire.org.uk/covers/cover-25.htm.
39701 Journal Article van der Loop, J.M.M., J. Tjampens, J.J. Vogels, H.H. van Kleef, L.P.M. Lamers, and R.S.E.W. Leuven. 2020. Reducing nutrient availability and enhancing biotic resistance limits settlement and growth of the invasive Australian swamp stonecrop (Crassula helmsii). Biological Invasions 22(11):3391-3402. https://doi.org/10.1007/s10530-020-02327-0.
39700 Journal Article van der Loop, J.M.M., L. de Hoop, H.H. van Kleef, and R.S.E.W. Leuven. 2018. Effectiveness of eradication measures for the invasive Australian swamp stonecrop Crassula helmsii. Management of Biological Invasions 9(3):343-355. https://doi.org/10.3391/mbi.2018.9.3.16.
42282 Journal Article van der Loop, J.M.M., L.S. van Veenhuisen, M. van de Loo, J.J. Vogels, H.H. van Kleef, and R.S.O.W. Leuven. 2023. Invasive Australian swamp stonecrop (Crassula helmsii) negatively affects spawning but accelerates larval growth of the endangered natterjack toad (Epidalea calamita). Hydrobiologia 850:699-714. https://doi.org/10.1007/s10750-022-05117-y.
39703 Journal Article van der Loop, J.M.M., M. van de Loo, W. de Vries, L.S. van Veenhuisen, H.H. van Kleef, and R.S.E.W. Leuven. 2022. Lessons learnt from large-scale eradication of Australian swamp stonecrop Crassula helmsii in a protected Natura 2000 site. Management of Biological Invasions 13(1):101-117. https://doi.org/10.3391/mbi.2022.13.1.06.
39698 Report Van der Loop, J.M.M., R. Beringen, R.S.E.W. Leuven, J.L.C.H. van Valkenburg, H.H. van Kleef, M. Verhofstad, and O. Baudewijn. 2020. Risk assessment of Australian swamp stonecrop (Crassula helmsii) in Europe. FLORON, Nijmegen, Netherlands. Risk assessment of Australian swamp stonecrop (Crassula helmsii) in Europe.
45518 Journal Article van Doorn, J., E.C.H.E.T. Lucassen, M.I.J.T. van Roosmalen, and A.J.P. Smolders. 2024. Carbon limitation and aluminium toxicity prevents dominance of Crassula helmsii on weakly buffered soils. Aquatic Botany 191:103737. https://www.sciencedirect.com/science/article/abs/pii/S0304377023001225.
39704 Thesis or Dissertation Varia, S. 2020. Investigations into the potential of classical biological control of the invasive aquatic weed, Crassula helmsii. Unpublished Ph.D. dissertation. University of London, London, England. https://pure.royalholloway.ac.uk/portal/files/39759442/2020VariaSPhD.pdf.
39707 Conference Proceedings Varia, S., S.V. Wood, C. Pratt, R. Adair, and S. Murphy. 2019. Proceedings of the XV International Symposium on Biological Control of Weeds. Pages 242-243 in Hinz, H.L., M.C. Bon, G. Bourdôt, M. Cristofaro, G. Desurmont, D. Kurose, H. Müller-Schärer, M. Rafter, U. Schaffner, M. Seier, R.F.H. Sforza, L. Smith, S. Stutz, S. Thomas, P. Weyl, and R. Winston, eds. A mitey solution to Australian swamp stonecrop.
39706 Journal Article Varia, S., S.V. Wood, R.M.S. Allen, and S.T. Murphy. 2022. Assessment of the host-range and impact of the mite, Aculus crassulae, a potential biological control agent for Australian swamp stonecrop, Crassula helmsii. Biological Control 167:104854. https://doi.org/10.1016/j.biocontrol.2022.104854.
34242 Journal Article Verbrugge, L.N.H., G. van der Velde, A.J. Hendriks, H. Verreycken, and R.S.E.W. Leuven. 2012. Risk classifications of aquatic non-native species: Application of contemporary European assessment protocols in different biogeographical settings. Aquatic Invasions 7(1):49-58.
29346 Web Page Washington State Department of Ecology. 2017. Aquatic plant management - aquatic herbicides>. http://www.ecy.wa.gov/Programs/wq/plants/management/aqua028.html. Accessed on 01/13/2017.
29474 News Watson, W. 1999. Amphibians and Crassula helmsii. Froglog Newsletter of the Declining Amphibian Populations Task Force. 31:2. http://www.amphibians.org/froglog/fl031/.
39710 Journal Article Wilcox, M. 2017. Occurrence of Crassula helmsii in Auckland. Auckland Botanical Society Journal 72(2):117-119. https://bts.nzpcn.org.nz/site/assets/files/24145/ak_bot_soc_journal_72_2_dec_2017_117-119.pdf.
39944 Report Williams, F., R. Eschen, A. Harris, C. Pratt, R.S. Shaw, S. Varia, J. Lamontagne-Godwin, S.E. Thomas, and S.T. Murphy. 2010. The Economic Cost of Invasive Non-Native Species on Great Britain. Center of Agriculture and Bioscience International, Egham, Surrey United Kingdom.


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Citation information: U.S. Geological Survey. [2026]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [1/13/2026].

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