[APWG] Jewelweed

[Maze, Dominic]

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<mailto: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


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.plantconservation.org/pipermail/apwg_lists.plantconservation.org/attachments/20110719/f30de479/attachment.html>