Cerumen wrote:

My real point was just that really, any garden or land in general will
contain a large number of plants which are toxic to animals and/or humans
but we are not encouraged to destroy them. Brugmansia and Gloriosa are not
native however whereas those examples I gave are.

As I said elsewhere in this thread I think the issue with ragwort is
the number of seeds that a single ragwort plant can produce and the
distance they can travel. A single plant in your garden can produce
enough seed to infest an adjacent field quite quickly. This is not so
true of most other poisonous plants (though I don't know about the
specific ones mentioned).

The other problem is its insidiousness, the major risk is that of
making hay from a pasture infested with ragwort and then that hay
getting sold to unknowing animal owners. The animals may not be
seriously affected by the poison until several years later.

The risk is not, generally, of animals eating live ragwort whether or
not it's on their owner's land, someone's garden or a road verge.

--
Chris Green )