Gomphocarpus fruticosus (L.) R. Br. (syn.: Asclepias fruticosa L.; incl. G. physocarpus E. Mey. and/or hybrids between these species) (S Afr.) – An exceptional escape from cultivation or garden throw-out. Scattered individuals were observed on rough ground in Roeselare in 2017, doubtlessly from discarded garden debris.
Gomphocarpus fruticosus is a very variable species. Goyder & Nicholas (2001) distinguished several subspecies. In addition, species boundaries between this species and G. physocarpus, a species sometimes considered conspecific with it, are weak and hybrids are known to occur (pers. comm. Goyder; see also Bullock 1952). Plants found in the horticultural trade may represent such hybrids rather than pure species, at least in part. Floral characters of the plants found in Roeselare correspond with G. fruticosus (corona with well-developed proximal tooth), whereas the subglobose follicle without distinct beak are typical of G. physocarpus. G. fruticosus is therefore accepted in a broad sense here, including G. physocarpus.
Gomphocarpus fruticosus is an invasive weed in many warm-temperate regions, including the Mediterranean area. In Belgium it probably is not hardy.
Bullock A.A. (1952) Notes on African Asclepiadaceae. I. Kew Bulletin 7: 405-426.
Fernández Haeger J., Jordano Barbudo D., León Meléndez M. & Devesa J.A. (2010) Gomphocarpus R. Br. (Apocynaceae, Subfam. Asclepiadoideae) en Andalucía occidental. Lagascalia 30: 39-46. [available online at: https://idus.us.es/xmlui/handle/11441/55796]
Goyder D.J. & Nicholas A. (2001) A revision of Gomphocarpus R. Br. (Apocynaceae: Asclepiadeae). Kew Bulletin 56: 769-836. [available online at: https://www.researchgate.net/profile/A_Nicholas/publication/263523600_A_...