Beneficial noxious weeds

[Cris Guppy & Aud Fischer]

Spotted knapweed is definitely highly detrimental to butterflies and most
other native species. Once established it forms dense monocultures that
completely eliminate all native plants. Without the native plants upon which
larvae feed, there are no butterflies. It is a good nectar source, but if
there are no butterflies to use it it is without value.

In contrast, bull thistle (a native species) in BC only becomes abundant in
areas highly degraded by over grazing or other events. Canada thistle
(introduced) also is generally only abundant in disturbed habitats, but can
form dense monocultures that eliminate all other plants.

-----Original Message-----
From: John Shuey <jshuey at tnc.org>
To: lep list <leps-l at lists.yale.edu>
Date: January 21, 2000 8:56 AM
Subject: Re: Beneficial noxious weeds


>Before folks get too enamored with weeds that can wreck ecological havoc,
take
>a look at the following two web pages. the first will take you to a
specific
>page for spotted knapweed, (which is known to have eliminated local demes
of
>Karner blues).  This is in no way a beneficial species, even if butterflies
do
>take nectar from it.
>
>http://tncweeds.ucdavis.edu/esadocs/documnts/centmac.html
>
>The next link is the searchable database, which will allow you to find
>authoritative information on almost all the major wildland weeds that cause
>ecological disruption in the US (including Hawaii and Puerto Rico) and
adjacent
>portions of Mexico and Canada.
>
>http://tncweeds.ucdavis.edu/esadocs.html
>
>Take a close look species before you try and  paint them in a pleasant
light.
>And note that native milkweeds are not considered by The Conservancy to be
>wildland weeds - although other organizations may consider them to be
>agricultural pests.
>
>--
>John Shuey
>Director of Conservation Science
>Indiana Office of The Nature Conservancy
>
>phone:  317-923-7547
>fax:  317-923-7582
>email:  Jshuey at tnc.org
>
>