In article , Nick Maclaren
writes
In article ,
Stewart Robert Hinsley wrote:
In article , Nick Maclaren
writes

But, if I recall, there is also one which established itself in the
UK by natural hybridisation between an introduced species and a
native one. Now, that is clearly a good species, and the usual
interpretation is that it would be native to somewhere. But, if
not the UK, where? Cockaigne?

Spartina anglica, Senecio cambrensis, Senecio eboracensis, and probably
more (maybe a Rubus, Hieracium or Taraxacum microspecies or several).

Thanks very much.

Now, can you answer my question? The reply "no" is acceptable :-)

I would say that the above named species are native to Britain, but that
depends on depends on the precise definition of nativity used. However,
consider Primula kewensis, which is an allopolyploid derivative of two
Chinese species, which, IIRC, arose in cultivation in Britain. That does
seem to be native to nowhere, so perhaps we could say the same of
Spartina anglica with a clear conscience.
--
Stewart Robert Hinsley