I came across a dense stand of 3-4ft tall plants by a small stream through a sandy beach (Cala di Luna) in NE Sardinia last June, with lanceolate Oleander like leaves and odd white flowers in umbellate clusters with 5 recurved white sepals and 5 "tubular" petals around a large central stigma. I can't even place it to family so have no idea what it is. Does anyone have a clue what it might be? It may not be native to Sardinia.
SOLVED: Unusual White Flowers in Sardinia
Looks like a milkweed. Maybe Gomphocarpus fruticosus.
Many thanks, Kell I'm pretty sure you've nailed it, at least to genus (G physocarpus is very similar and hybridises with G. fruticosa). It is a South African plant (I just knew it wasn't European!) and I've now come across lots of photos labelled G. fruticosus in Sardinia both flowering and with weird inflated seed pods (G. physocarpus is sometimes known as Bishop's balls!: https://en.wikipedia.org/wiki/Gomphocarpus_physocarpus). I'd have recognised it if it had been fruiting as I've seen Gomphocarpus seed pods in Greece before.