Re: Re: Invasive Plants

**"Lon J. Rombough" lonrom@hevanet.com>**

> Perhaps we should distinguish between invasives that escape but cause no
> appreciable harm and those that do.  There are countless naturalized
> species in every region that do little or no harm.  Yarrow (Achillea
> millefolium) and wild carrot (Daucus carota) are just two that are
> common in my area (southern Ontario): both have been naturalized here
> for a long time, probably for centuries.  Neither of these plants is
> considered to be noxious to farmers or others in any way.  It seems to
> me that to condemn a plant just because it escapes is simpleminded.  I
> don't mean to suggest that the two species mentioned by Carol are not
> problems; they could very well be.  I honestly don't know about those
> two because I have not seen them in the wild.  But I think it would be
> helpful to everyone to narrow the debate on invasives to only those that
> are known to be problems.

Interesting comment on Yarrow.  When I took population genetics, it was one
of the plants studied because it has become so varied in the wild.  There
are populations with different chromosome levels, bloom time, and a lot of
other differences.  It shows up almost exclusively in disturbed land,
particularly along roadsides, which is one reason it is studied so much -
the populations are easy to reach.  Different populations have been well
mapped in the Pacific NW.   Obviously it has done a lot of adapting, to the
point that it has become part of the ecosystem.

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