Bob Hobden wrote:
"Nick Maclaren" wrote .after..
david taylor wrote:
We've had many communications on horsetail, particularly because
it
is impossible to eliminate. It must be sensitive to growing
conditions/competition from other plants otherwise it would take
over the country.
Can anyone put any definition as to its preferences or
vulnerabilities?

"It"? There are a fair number of species native to the UK.
Generally, damp soils where they can get their roots down, but the
common horsetail is pretty widespread. I don't know why it only
rarely becomes an invasive plant.

On our old allotment site it moved across in a wave, very thick at
the front and after it passed we are left with just a few which hoe
off easily reducing them even more. I've seen the same thing on our
local railway line, a very prolific wave front moving slowly along
and then just a few left behind, and I wonder if they will
eventually die out until the next infestation.

That sounds interesting. I've never had much to do with these plants,
and thought they were fixtures like most others. I wonder if they
eventually exhaust the soil of some nutrient which isn't quickly
replaced by natural processes, and so have to move constantly onward.
Could the plants' high silica content in some way have a bearing on
this? Or is there some complex mycorrhizal association which can
peter out in less than perfect conditions?

(A moment of horror on GW the other night, when some proud
nurserywoman presented her lovely aquatic horsetail; I hope it can't
grow out of water!)

--
Mike.