[APWG] Jewelweed

Tue Jul 19 18:41:01 CDT 2011

JewelweedAll:

Shaw makes some excellent points, but just one additional caution, if I may, with respect to "management." Many if not most "control" and "eradication" efforts, while perhaps viscerally satisfying ("Ding-dong, the witch is dead!"), do more damage than good. For example, I have seen "treated" areas grow more, not less weedy, following such measures. Glyphosate can be particularly damaging to emerging plants, unseen by the "certified" pest-controllers. Cryptogamic species are particularly susceptible to tiny, unseen aerosols; ironically, it is just such species which help to prevent the seed of some invasive species from germinating, while leaving them exposed to granivores and pathogens. Messing with Mother Nature is a lot more complicated than many presume. 

WT

"Nine-tenths of the hell being raised in the world is well-intentioned." -Anon.

  ----- Original Message ----- 
  From: Shaw, Sasha 
  To: 'Maze, Dominic' ; 'Katie Fite' ; apwg at lists.plantconservation.org 
  Sent: Tuesday, July 19, 2011 1:48 PM
  Subject: Re: [APWG] Jewelweed

  Katie, are you sure of the species?  There are Impatiens species similar to I. capensis with yellow and orange flowers that are native to the western US.  I'm not very familiar with the ones not found out here on the coast, but Peter Zika's article on the new hybrid (referenced in Dominic's email below) has a good key to Impatiens in the Pacific Northwest.  Look especially at I. parviflora and I. aurella as well as I. ecalcarata that Dominic mentions below.  We also had confusion here with a yellow flowered species called I. noli tangere, which I believe is just found on the northwest coast of the US and Canada.  When we were trying to determine what species we had here in western WA, I felt fortunate that we weren't east of the Cascades, because it gets more confusing over there with more native Impatiens with orange and yellow flowers.  

  I've been following the discussion and research about I. capensis with interest.  In King County, WA we list it as a Weed of Concern because it does invade pretty pristine areas that otherwise mostly have native species and because it does at times grow very densely and could perhaps impact other riparian herbaceous species.  It also certainly takes advantage of disturbance and openings quite easily and quickly and seems to persist and become more abundant over time.  Also, Peter Zika's research found that it apparently is attracting pollinators away from our much less common native I. ecalcarata (spurless jewelweed) which has less nectar.  Both the new hybrid and I. capensis have more nectar and attract more pollinators.  This means the seed set of the native I. ecalcarata is reduced.  He found that the range of the I. ecalcarata is declining and I. capensis and the hybrid are increasing, perhaps due to this issue or to being less competitive.  This seems reason enough to call I. capensis a problem on the west coast.  However, it is not nearly as bad a problem here as I. glandulifera, which is much more aggressive and dominates sites much more.  I'm not sure if it makes sense to chase down I. capensis everywhere, but probably it should be prevented from spreading more into our more remote areas where it is starting to encroach.

  One caution about removing I. capensis in our region (the Pacific Northwest) is that it can't be safely distinguished from I. ecalcarata and the hybrid until it is in flower.  Generally speaking the I. ecalcarata flowers are orange, don't have spurs and don't have any spotting.  I. capensis and the hybrids all have either spurs, spots, or both.  Again, I would refer folks to the Zika articles for more info and an accurate key.

  Also, as a comment on other posts on this plant, I agree that it is important to distinguish between mostly ruderal or opportunistic non-native plant species (weeds) and those non-natives that are truly invasive and able to escape into and thrive in ecosystems in their new location at the expense of the species that are native to that ecosystem (invasive weeds or invasive plants).  It's not always easy and there is certainly a lot of overlap between the groups, but we do need to prioritize so we can focus on the species that could cause the most harm if they were ignored.  That said, it's not always obvious which species are going to cross that line to becoming invasive instead of just opportunistic.

  Most introduced species start showing their weediness in disturbed areas first and we want to act quickly before new invaders get entrenched, so when do we know for sure how much harm a species could cause (but before it has done that harm and it's too late to stop it)?  How do we act early enough to be effective, but not over-react to all non-native plants?  In our county, we look for introduced plants that have shown up where they were not planted and that have reproduced successfully and are thriving, apparently at the expense of native plants.  At that point, it seems to me it would be wise to take action to stop its spread.

  <<>><<>><<>><<>><<>><<>><<>><<>> 

  Sasha Shaw

  King County Noxious Weed Control Program

  201 S. Jackson St., Suite 600

  Seattle WA 98104

  206-263-6468

  sasha.shaw at kingcounty.gov 

  www.kingcounty.gov/weeds 

  From: apwg-bounces at lists.plantconservation.org [mailto:apwg-bounces at lists.plantconservation.org] On Behalf Of Maze, Dominic
  Sent: Tuesday, July 19, 2011 8:42 AM
  To: 'Katie Fite'; apwg at lists.plantconservation.org
  Subject: Re: [APWG] Jewelweed

  Hi Katie et alia,

     Impatiens capensis is, in my experience, a problematic species here west of the Cascade Range in the Pacific NW.  The densities of this sp. are pretty amazing with the understory of riparian corridors often dominated by it.  I've been seeing more and more of it in the Willamette Valley and surrounding ranges here in Oregon with seemingly little attention paid to it.

     Interestingly, some land managers still consider this species native here on the West Coast, probably due to confusion with our native, I. ecalcarata in some older floras and field guides.  Ed Alverson of TNC wrote a short comment in reply to a posting on I. capensis at the Botany Photo of the Day website:

  "Impatiens capensis is an introduced and invasive species in the Pacific Northwest, west of the Cascades. Peter Zika addressed this issue in a 2006 paper, "The status of Impatiens capensis (Balsaminaceae) on the
  Pacific Northwest coast", published in the Journal of the Torrey Botanical Club, vol. 133 pp. 593-600. In fact, I. capensis is spreading into the habitats of the uncommon native I. ecalcarata west of the Cascades, and the two species are hybridizing. This has created a situation where the native species is potentially being out-competed by both the introduced species and by their hybrids. Zika has published another paper on the hybrid, which he has named Impatiens x pacifica, see "Impatiens x pacifica (Balsaminaceae), a New Hybrid jewelweed from the Pacific Northwest Coast of North America", Novon vol. 16, pp. 443-448, 2006."

  Add this spp. to I. glandulifera (a big problem) and I. balfourii (an escaping species which may be a problem in the future), and we've got our hands full out here with the touch-me-nots.

  Dominic Maze | Invasive Species Coordinator 

  City of Portland Environmental Services

  1120 SW 5th Avenue, Room 1000

  Portland, Oregon 97204

  p:  (503) 823-4899

  f:   (503) 823-5344

  dominic.maze at portlandoregon.gov

------------------------------------------------------------------------------

  From: apwg-bounces at lists.plantconservation.org [mailto:apwg-bounces at lists.plantconservation.org] On Behalf Of Katie Fite
  Sent: Monday, July 18, 2011 5:46 PM
  To: apwg at lists.plantconservation.org
  Subject: [APWG] Jewelweed

  Has anyone had any experience with jewelweed (Impatiens) native to the eastern U. S. becoming weedy in valley marsh habitats in the intermountain West? 

  I see that jewelweed Impatiens capensis (orange jewelweed) is listed as a King County  (WA) "Weed of Concern". 

  This species is shown as having a yellow flowered form, which is what we are seeing.

  http://www.kingcounty.gov/environment/animalsAndPlants/noxious-weeds/laws/list.aspx

  Katie Fite
  Western Watersheds Project
  katie at westernwatersheds.org

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