[Herbalist] Re: Imported Species, Redux.

[Kathleen H. Keeler]

Jadwiga wrote:

> > >There go all the wonderful "native" English herbs - they were shipped to
> > >England from the Mediterranean & Middle East.  According to that logic, ...
> > The rosemary, creeping thyme, or banana trees are not crowding out any of
> > the other native (or even other imported) species, nor do they proliferate
> > unchecked.  They remain controlled, rather than expanding almost
> > exponentially.
>
> While rosemary and creeping thyme are not considered to be invasive <>, it's
> important to
> realize that many European herbs have escaped into the wild and that some
> herbs are actually on the 'dangerously invasive, do not plant' lists in
> some states. Many of our common weeds such as dandelion, plantain, fat
> hen, purslane and others are invasive newcomers from the old world. Mint
> and other plants (the tansy in my garden comes from an original shoot dug
> up by the side of the road in NY State) are so entrenched in the US that
> many people think they are native.

   I agree.  Weeding the lawn, most of the plants are European in origin and have
some traditional medicinal use.

   For successful invasion, multiple introductions are usually needed.

    Likewise, exotic plants and animals that become pests usually spend several
decades as naturalized but not particularly abundant.  I served on several panels
about the risks of novel weeds from transgenic plants (for Audubon, USDA, National
Academy of Sciences, back in the 80s) and one of the intractable problems was that
escaped transgenics that became serious weed problems would be expected to be
years building population sizes large enough to reach "outbreak" status, and by
then you couldn't realistically expect to eradicate them. Eradication is possible
when numbers are low, but at that point the plants seem harmless.

   I don't think all native are good and all nonnatives are bad, but I also don't
think we'll like the consequences of bringing all the world's plants into, say,
the central US. The resources of the region won't support everything at once and
some extinction will occur.  If it is the natives we lose, that'd be a shame,
since they're not found elsewhere.  My ecology research is on natives that have no
particular "value" and so nobody knows anything about--how long do they live? what
pollinates them? what eats them?--and I suppose nobody will miss them if they go
extinct because cheatgrass, leafy spurge and spotted knapweed took up all the
water.   Still, I generally take the tack that we should save plants for our
grandchildren to let go extinct:  that way they have choices.

Plants have always migrated when they could, people have always carried plants
around, more than 90% of the species that ever lived are extinct...you can easily
justify "let nature do it" and just enjoy watching the process of change.  But
maybe since we're so much part of the cause of plant migration and extinction, we
might fairly intervene not to have leafyspurgelands replace our grasslands.  --In
the Age of Dinosaurs, before grasses evolved, the flat lands of the central US,
where they were not under that inland sea, were covered by ferns.  A fern
prairie!  There's no reason our current plants cannot be replaced by better
competitors.

Agnes
(My yard is a weird mix of Native American plants and Period herbs! as I pursue
both interests.)