Tree Mallow (Lavetera arborea) is a migrant. It can be found in the British Isles, western Europe and around the European and African sides of the Mediterranean- but only on the coasts. It is salt tolerant, the fruits float and the seeds within have a hard coating. Thus the seeds can be distributed both by tides and seabirds which explains its widespread range which is nonetheless restricted to not much further inland than the foreshore.
 It has also been cultivated in gardens but in the wild it is a maritime plant. I saw these ones yesterday along a stretch of shingle beach between Whitstable and Herne Bay on the North Kent coast.

 Like many plants the Tree Mallow has other common names e.g. Sea Mallow. Botanical Latin is supposed to provide the definitive nomenclature but curiously it has several Latin names as well. Lavetera arborea is one of them but it is often referred to as Malva arborea (which places it in another genus) and also as Malva dendromorpha and Malva eriocalyx.
 Perhaps it's appropriate that no-one is quite sure what to call this traveler.