La Puce writes

K wrote:
It is not lack of pollution which makes oak or ivy able to support a
large variety of creatures in the UK, it's the fact they have been
around a long time. A native of an area which shares a similar fauna
will obviously support a good variety, a native of an area with a
completely different fauna will not provide support for the different
fauna of the UK.

Hmmm. Sure. But wouldn't you say that planting a lawn only with a
couple of rose bushes will not provide sufficient habitat for the fauna
of the UK? And ....

Was anyone suggesting it would?

I'm getting confused by your talking of planting of different verbenas -
previously it was V bonariensis you were talking about, not V
officinalis

... in this case, planting any kind of verbena variety would increase
the wild life habitat, regardless of the verbena's species?! Because
I'm also very confused. When I offered a suggestion of a 'wild effect'
of planting for Kate I was told by yourself and Sacha that
v.bonariensis wasn't uk native, but v.officinallis was. I've checked it
and English Nature encourage the planting of v.bonariensis presicely
because it encourages wild habitat and life in the garden.

I don't know what EN are recommending or why. Stace describes V
officinalis as native and I have seen it growing in the wild. I have not
seen V bonariensis in the wild. Stace describes it as introduced-casual,
on tips and waste ground.

I finally
said the insects in my garden couldn't care less of the species of
verbena, nor would care if my marguerite came from abroad! There lies
my confusion - this 'uk native' label is very flawed I think. Or I'm a
noodle, again ;o)

It's flawed in that most of our flora and fauna probably came from
elsewhere, if you go far back enough in time (the alternative is that
the species differentiated enough to become a true species actually
within what is now the UK), but for practical purposes there is a
distinction between species which have been growing wild for long enough
for their origins to be uncertain and species which are known to have
been introduced.

As I said elsewhere, if the species in question is one that originated
in a similar habitat, with similar flora and fauna to ours, then it will
support our species. But if it is from somewhere entirely different,
then, while it may support some of our generalist species, it is
unlikely to support our specialists.

There are a large number of people who think that our native flora are
worth preserving, and that one should not plant introduced species in
the wild. The ill effects of planting introduced species in the wild
range from pure competition ousting native plants from the area
(Rhododendron ponticum, Himalayan balsam, parrot feather for example) to
cross breeding with natives (eg spanish bluebell) with effects that we
do not fully understand.

--
Kay