Seedhead ID

[Hornbeam]

These seedheads look like clematis to me, but are they? They don't look quite right, nor do the leaves. They were growing on a remote sandy shore on Mersea Island in Essex. They are far from any hedgerows or houses.

[aeshna5]

They are definitely Clematis seedheads, but can't see the foliage well enough to see which species. Only 1 native- C.vitalba (Old man's beard), but C.flammula is found in several counties by the sea. Other species are also known to be naturalised.