Impatiens capensis Meerb. (syn.: I. biflora Walter, I. fulva Nutt.) (N-Am.) – A rare but recently much increasing and locally naturalized alien. Probably a garden escape. First discovered in 2002 on the borders of an artificial water body near Duffel (AWW-bekken) and soon extending to neighbouring suitable habitats (e.g. Anderstadvijver). At present known from several locations in the valley of river Nete: along Molenbeek in Emblem, in nature reserve Viersels Broek near Viersel, borders of Netekanaal between Duffel and the Albertkanaal in Zandhoven, etc. Since 2011 also observed along Zeekanaal, for instance in Humbeek (Grimbergen) and Puurs (and very likely widely overlooked elsewhere along this canal) and since 2013 known from canal Leuven-Dijle near Mechelen and since 2015 from Schipdonkkanaal near Zomergem. In 2017 first observed along river Leie between Kuurne and Wervik (Stien 2018). A further expansion, especially in these areas, is very likely.
Impatiens capensis inhabits more or less the same wet, nature-like habitats like I. glandulifera and possibly constitutes another threat to native vulnerable plant communities. Additional information on its incipient invasive behaviour in the Netherlands is available here: http://www.q-bank.eu/Plants/BioloMICS.aspx?Table=Plants%20-%20Species&Re....
The exact provenance of Impatiens capensis remains unclear. According to most authors it is a garden escape but it is remarkably omitted in the extensive accounts of Grey-Wilson (1983, 1997) on Impatiens in cultivation (see, however, Jäger & al. 2008).
Selected literature:
Dardaine P. (1984) Impatiens capensis Meerb. (Impatiens biflora Walter): nouvelle espece pour la Meurthe-et-Moselle. Monde Pl. 415-416: 13-14.
Grey-Wilson C. (1983) A survey of the genus Impatiens in cultivation. The Plantsman 5(2): 86-102.
Grey-Wilson C. (1997) Impatiens. In: Cullen J. & al. (eds.), The European Garden Flora, vol. 5. Cambridge University Press, Cambridge: 159-163.
Jäger E.J., Ebel F., Hanelt P. & Müller G. (eds.) (2008) Rothmaler Band 5. Exkursionsflora von Deutschland. Krautige Zier- und Nutzpflanzen. Springer Verlag, Berlin: 880 p.
Krogerus H. (1977) Impatiens capensis (Balsaminaceae) inford till Lojo-omradet i sydvastra Finland. Mem. Soc. Fauna Flora Fenn. 53(2): 99-100.
Knebel I. (1999) Impatiens capensis Meerb. in der Urdenbacher Kampe - erster nachweis dieses springkrautes in NRW? Florist. Rundbr. 32(2): 123-125.
Lu Y. (2002) Why is cleistogamy a selected reproductive strategy in Impatiens capensis (Balsaminaceae)? Biol. J. Linn. Soc. 75(4): 543-553.
Ludwig W. (1994) Impatiens capensis Meerb. in Hessen: ein erster Bericht. Hess. Flor. Briefe 43(1): 14-16.
Nawrath S. (1996) Weitere Vorkommen von Impatiens capensis in Hessen. Botanik und Naturschutz in Hessen 8: 105-108.
Pawlaczyk P. & Adamowski W. (1991) Impatiens capensis (Balsaminaceae): nowy gatunek we florze Polski. Fragm. Flor. Geobot. 35(1-2): 225-232.
Reichert H. (2001) Die Ausbreitung des Neophyten Impatiens capensis am Mosel-Ufer bei Mehring: ein instruktives Beispiel für Hydrochorie. Decheniana 154: 29-31.
Schmitz U. (2003) Impatiens capensis Meerb. am unteren Niederrhein - Weitere Ausbreitung und standörtliche Einnischung des Orangeblütigen Springkrautes. Floristische Rundbriefe 37: 31-36.
Simpson R.L. (1985) The comparative ecology of Impatiens capensis Meerb. (Balsaminaceae) in central New Jersey. Bull. Torrey Bot. Club 112: 295-311.
Sommer M. (1995) Über die weitere Ausbreitung von Impatiens capensis Meerb. an der Lahn. Hess. Flor. Briefe 44(2): 17-19.
Stien B. (2018) Discussion à propos de quatre découvertes régionales en 2018: Scabiosa atropurpurea, Dittrichia viscosa, Tragopogon pratensis subsp. orientalis et Impatiens capensis. Bull. Soc. Bot. N. Fr. 71: 21-28.
Winsor J. (1983) Persistence of habitat dominance in the annual Impatiens capensis (Balsaminaceae). J. Ecol. 71: 451-466.
Zika P.F. (2006) Lectotypification of the names of two color forms of Impatiens capensis (Balsaminaceae). Rhodora 108: 62-64.