2. Ambrosia psilostachya DC. (syn.: A. coronopifolia Torr. et A. Gray) – A rare but locally naturalised alien. First introduced in 1917 in the seadunes near Koksijde, possibly by American troops (along with several other North American aliens). Subsequently regularly confirmed in this area (for instance in 1947) and still present today in the surroundings of Koksijde and Oostduinkerke (at least two small populations; as confirmed in 2011). Likewise, Ambrosia psilostachya is known from the Belgian coast in Zeebrugge, at least since 1955 and still present as a lawn weed near the railway station. Also known since the 1950's from the surroundings of Mol (canal banks). One population, at the power plant in Mol, persists since at least 1982 (confirmed in 2012). Furthermore recorded from several other locations, in Flanders as well as in Wallonia. Often long persistent and locally naturalised for some time but most probably gone now in most of these places. For instance in Damprémy (Charleroi), between 1929 and 1948, Grobbendonk, between 1951 and 1957, etc. In 2011 still recorded on waste land in Quaregnon near Mons.
Ambrosia psilostachya usually occurs in dry, sun-exposed habitats: ruderalised dunes, sandy road verges and canal banks, railway tracks or sand raised sites. In disturbed dune grasslands it might locally behave as an invasive species, like in the Netherlands (compare with Weeda 2009).
At present Ambrosia psilostachya is broadly circumscribed and includes A. coronopifolia. Most European (and all Belgian) records belong to the latter if they were separated (see also Lawalrée 1947).
 |
 |
Selected literature:
Bassett I.J. & Crompton C.W. (1975) The biology of Canadian weeds, 2. Ambrosia artemisiifolia L. and A. psilostachya DC. Canad. J. Pl. Sci. 55: 463-476.
Červinka Z. & Sádlo J. (2000) Neofyty Ambrosia psilostachya a Celastrus orbiculatus v městě Čelákovicích. Muz. a Současnost, ser. natur. 14: 65-68.
Lawalrée A. (1947) Les Ambrosia adventices en Europe occidentale. Bull. Jard. Bot. État Bruxelles 18: 305-315.
Verloove F. (2002) Ingeburgerde plantensoorten in Vlaanderen. Mededeling van het Instituut voor Natuurbehoud n° 20: 227 p.
Verloove F. (2006) Ambrosia coronopifolia. In: Van Landuyt W., Hoste I., Vanhecke L., Van den Bremt P., Vercruysse W. & De Beer D., Atlas van de flora van Vlaanderen en het Brussels gewest. Instituut voor Natuur- en Bosonderzoek, Nationale Plantentuin van België en Flo.Wer: 133.
Weeda E.J. (2009) The role of archaeophytes and neophytes in the Dutch coastal dunes. J. Coast Conserv. 14(2): 75-79.