Asclepias syriaca

Asclepias syriaca L. (syn.: A. cornuti Decaisne) (N-Am.) – A rare and usually ephemeral or temporarily persistent alien, mostly an escape from cultivation. First seen on a ground heap in Lichtaart in 1987. Furthermore recorded against a fence in the port of Antwerpen in 1995, without obvious vector of introduction. Observed several times as an escape on wasteland in Brussel in 2004. A well-established population (several tens of plants) has been recorded in a road verge in Wandre since 2007, obviously as an escape or throw-out from a nearby garden. It was confirmed there in 2017. It is apparently slightly increasing recently (seen, for instance, in Begijnendijk, Dessel, ... although often as a mere relic of cultivation) and possibly becoming naturalized locally (see also van der Meijden 2005). A large population in Etalle, comprising at least 100 individuals, will be eradicated.

Additional information on the presence of Asclepias syriaca in western Europe is available at:

The very similar North American species Asclepias speciosa may have been overlooked (Gudžinskas & al. 2019).

Herbarium specimen

Selected literature

Bhowmik P.C. & Bandeen J.D. (1979) The biology of Canadian weeds: 19. Asclepias syriaca L. In: Mulligan G.A. (ed.). The biology of Canadian weeds: contributions 1-32. Ottawa, Agriculture Canada. 221-231.

Gaertner E.E. (1979) The history and use of milkweed (Asclepias syriaca L.). Econ. Bot. 33(2): 119-123.

Gudžinskas Z., Petrulaitis L. & Žalneravičius E. (2019) Asclepias speciosa (Apocynaceae, Asclepiadoideae): a rare or unrecognized alien species in Europe? PhytoKeys 121: 29-41. [available online at:]

Sengl P. & Rehorska R. (2017) Asclepias syriaca, Gewöhnliche Seidenpflanze (Asclepiadaceae) - Ein Neubürger der südlichen Steiermark mit Ausbreitungspotential. Mitt. Naturw. Ver. Steiermark 147: 67-76.

Valachovic M. (1989) Reproductive biology of Asclepias syriaca populations in Zahorska Nizina lowlands: 1. Notes on flower biology and fruit production. Biologia, A (Czechoslovakia) 44(1): 37-42.

Van der Meijden R. (2005) Heukels’ Flora van Nederland (23e druk). Wolters-Noordhoff, Groningen: 685 p.

Weinert E. (1981) Asclepias syriaca L., im herzynischen Florengebiet. Mitt. Florist. Kart. 7: 127-130.

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith