Cardamine corymbosa Hook. f. (New Zealand) – A rare, locally naturalized alien. Known at least since the 1990’s from plant nurseries in West-Flanders and probably long) overlooked before. In 2005 specimens were collected for the first time outside of the container nursery industry: in a private garden in Aalter and in the Botanic Garden (Kruidtuin) of Leuven (Hoste & al. 2008). Since then, C. corymbosa has been observed on rather numerous occasions, in Flanders as well as in Wallonia, although most records are from the northern part of the country. An up-to-date overview of recent records is available here: https://waarnemingen.be/soort/view/18348.
In addition to plant nurseries (where it can be a serious weed) Cardamine corymbosa has been observed in several types of habitats but a link with the horticultural trade is always obvious: church yards, urban habitats (between cobble stones close to ornamental plantations), as garden weed, etc. The species is by far most often seen in cemeteries. Although such habitats are frequently disturbed, C. corymbosa easily persists and can be considered naturalized. In the oldest known locality (Leuven) its presence is still regularly confirmed.
Cardamine corymbosa is known in identical circumstances from several other European countries. It was probably first introduced to the British Isles from where it is known since the 1970’s (Braithwaite 1991). It probably passed unnoticed for many years, especially since it was initially confined to plant nurseries and gardens. In the past two decades it has been reported from, for instance, Austria, France, Germany, Netherlands, etc. (see references).
Selected references
Bomble F.W. (2011) Kritische und wenig bekannte Gefäßpflanzenarten im Aachener Raum. Online-Veröff. Bochumer Bot. Ver. 3(8): 97-108. [available online at: https://core.ac.uk/download/pdf/14527500.pdf]
Braithwaite M. (1991) New Zealand Bittercress, Cardamine uniflora. B.S.B.I. News 58: 38-39. [available online at: http://archive.bsbi.org.uk/BSBINews58.pdf]
Braithwaite M. (2003) A crucifer with ‘no flowers to speak of’. Cleistogamy and prolifery in Cardamine corymbosa (New Zealand bitter-cress). B.S.B.I. News 92: 14-16. [available online at: http://archive.bsbi.org.uk/BSBINews92.pdf]
Dunkel F.G. (2010) Bemerkenswertes aus Unterfranken. Ber. Bayer. Bot. Gesell. 80: 171-174.
Evans T.G. (1999) Cardamine corymbosa Hook. f. - New Zealand Bitter-cress. Welsh Bull. Bot. Soc. British Isles 65: 12-13. [available online at: http://bsbi.org/wp-content/uploads/dlm_uploads/Welsh_Bulletin_65.pdf]
Garnock-Jones P. (1993) New Zealand bittercress, Cardamine corymbosa. B.S.B.I. News 64: 16. [available online at: http://archive.bsbi.org.uk/BSBINews64.pdf]
Heenan P.B. (2017) A taxonomic revision of Cardamine L. (Brassicaceae) in New Zealand. Phytotaxa 330(1): 1-154.
Hohla M. (2011) Cardamine corymbosa (Brassicaceae) und Bromopsis (Bromus) riparia (Poaceae) – neu für Österreich sowie weitere Beiträge zur Adventivflora von Oberösterreich, Niederösterreich und Salzburg. Neilreichia 6: 55–79. [available online at: http://www.zobodat.at/pdf/NEIL_6_0055-0079.pdf]
Hoste I. & Mertens P. (2008) A new alien in nurseries and gardens: Cardamine corymbosa Hook. F. in Oldenburg (Niedersachsen). Floristische Rundbriefe 41: 43-46.
Hoste I., Van Moorsel R.R.C.M.J. & Barendse R. (2008) Een nieuwkomer in sierteeltbedrijven en tuinen: Cardamine corymbosa in Nederland en België. Dumortiera 93: 15-24. [available online at: http://www.br.fgov.be/DUMORTIERA/DUM_93/Dum%2093_15-24_Cardamine%20corym...
Kent D.H. (1991) New Zealand Bittercress. B.S.B.I. News 59: 49. [available online at: http://archive.bsbi.org.uk/BSBINews59.pdf]
Post A., Neal J., Krings A., Sosinski B. & Xiang Q. (2009) New Zealand Bittercress (Cardamine corymbosa; Brassicaceae): New to the United States. Weed Technology 23(4): 604-607.
Pritchard G.G. (1957) Experimental taxonomic studies on species of Cardamine Linn. in New Zealand. Trans. Roy. Soc. New Zealand 84: 75-89. [available online at: https://paperspast.natlib.govt.nz/periodicals/TPRSNZ1957-85.2.5.5?query=...
Sauerwein B. (2011) Das Hersfelder Schaumkraut (Cardamine corymbosa HOOK.F.) im Hersfelder Kurpark neu für Hessen. Notizbuch 79 der Kasseler Schule: 251-253. [available online at: https://www.researchgate.net/publication/230707666_Das_Hersfelder_Schaum...
Stace C.A. (1994) Cardamine corymbosa in Leicestershire. B.S.B.I. News 67: 53-54. [available online at: http://archive.bsbi.org.uk/BSBINews67.pdf]
Weiss V. (2017) Erstfund von Cardamine corymbosa Hook. f., Neuseeland-Schaumkraut, in Mitteldeutschland. Informationen zur floristischen Kartierung in Thüringen 36: 59-60. [available online at: http://www.v-weiss.de/cardamine-corymbosa.pdf]
Weston I. (1991) Cardamine corymbosa in v.c.53, S. Lincs. B.S.B.I. News 59: 49. [available online at: http://archive.bsbi.org.uk/BSBINews59.pdf]