HomeMy WebLinkAboutPurple Loosestrife.pdf Purple Loosestrife (L. Scott) In riparian areas (L. Scott) Full bloom – Noxious stage
Maple Ridge Noxious Weeds Program
Purple Loosestrife
(Lythrum salicaria)
Designation: Provincially Noxious
Purple loosestrife
History:
Introduced from Eurasia and first recorded
in North America in 1814. It is now common
in the Lower Fraser Valley and is regarded as
a major concern, particularly in riparian
areas.
How to Identify:
Size: Perennial herb, growing to 3 m tall.
Flowers: Purple‐magenta spikes, blooming
from July to October.
Leaves: Opposite to whorled, dark green,
lance‐shaped.
Stem: Stiff, smooth, square, woody.
Location: Riparian areas, disturbed wet soil
areas (including roadsides), gardens.
Mistaken Identity: Can be confused with
native fireweed, but purple loosestrife does
not produce windborne seeds.
Danger / Impact
Aggressively invades riparian areas
displacing native vegetation.
Plant roots can alter waterways.
Reduces food sources for wildlife.
Each plant can produce up to 2.5 million
seeds. Can also reproduce by root
fragments.
Management:
Pull from base of plant, taking care to
remove all rhizomes. Small patches can be
dug. Remaining root fragments will re‐
sprout. Biological control (Galerucella
beetle) of large infestations is relatively
successful (and being used in the Fraser
Valley) but may require ongoing, repeat
introductions and will not lead to
eradication.
Timing: July to August when plant is blooming (and therefore
clearly visible) but prior to seeds appearing.
Disposal: Do not compost in home compost bin; put in
municipal site.
Follow‐up: Monitor at least once annually for re‐growth and
new seedlings. Eradication of large infestation is unlikely but
repeated annual treatment will contain the plant at lower
levels.
Restoration and Planting Alternatives:
Plant native or non‐invasive species including:
Native Plants:
Hardhack (Spiraea douglasii)
Red‐osier dogwood (Cornus stolonifera)
Willow species (Salix spp.)
Common bulrush (Typha latifolia)
Non‐Native Plants:
Blazing star (Liatris spicata)
Tall delphinium (Delphinium elatum)
Bloody iris (Iris sanguinea)
Hardhack (Spiraea douglasii)
Spike speedwell (Veronica spicata)
Fireweed – Native Species easily mistaken for
Purple Loosestrife
Distribution in DMR:
Small groups of plants found in only a few areas; a weed for
rapid response and containment.
Who Do you Call?
1) REPORT PROHIBITED WEEDS – Report‐A‐Weed: www.reportaweedbc.ca 1‐888‐WEEDSBC
2) DMR: 604‐467‐7363 – AND SEE: http://www.mapleridge.ca/714/Invasive‐Plant‐Species
Information and photos:
http://www.weedsbc.ca/pdf/purple_loosestrife.pdf
http://westvancouver.ca/sites/default/files/dwv/assets/home‐building‐property/docs/pets‐wildlife‐environment/Invasive‐Plants/APPENDIX_A_‐
_JANUARY_28__2014_DRAFT.pdf
http://linnet.geog.ubc.ca/
http://www.bcinvasives.ca/images/stories/plants/purpleloosetrife
http://iscmv.ca/target‐species/species‐profiles