Soapberry Sapindus sp. (Sapindaceae: Sapindoideae): drift endocarps from UK waters

Abstract

At least 13 species of Soapberry (Sapindus spp.) are currently recognized worldwide. At least two species are considered to be native to North America: Wing-leaf Soapberry S. saponaria L. and Florida Soapberry S. marginatus Willdenow. However, some authors consider that both of these species are synonymous. S. saponaria has been widely distributed by man throughout tropical regions of Central and South America, including the Caribbean Islands, Africa, India, Asia and Australia. Some Sapindus diaspores (fruits and seeds) inevitably find their way into rivers and eventually float out to sea where they are dispersed by oceanic currents and a few occasionally reach NW European waters, most likely from the Caribbean region via the Gulf Stream and North Atlantic Drift. The current review collates all known records of Sapindus endocarps found stranded in UK waters, including one previously unpublished record. Although the identification of Sapindus endocarps currently defy efforts to pin them down to species level, at least one the UK specimens was considered to be S. saponaria. Morphometric studies of Sapindus endocarps, combined with confirmatory genetic analyses, may help to resolve both the identity and provenance of drift endocarps found stranded in maritime regions on both sides of the North Atlantic.

Keywords:

• seaborne dispersal
• buoyancy
• floatation
• sea bean

Acknowledgements

We are grateful to the following for their assistance: Chilekwa Chisala (Vlaams Instituut voor de Zee vzw Flanders Marine Institute, Oostende, Belgium), Jim Clifford (University of Saskatchewan, Canada), Melia Knecht (King's Museum, University of Aberdeen, Scotland), Fiona Marwick (West Highland Museum, Fort William, Scotland), and Ed Perry (Melbourne Beach, Florida, USA).