Decodon verticillatus (Swamp Loosestrife)
Also known as: | Water Willow |
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Genus: | Decodon |
Family: | Lythraceae (Loosestrife) |
Life cycle: | perennial |
Origin: | native |
Status: |
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Habitat: | part shade, sun; swamps, lake shores, shallow mucky water |
Bloom season: | July - September |
Plant height: | 2 to 4 feet |
Wetland Indicator Status: | GP: OBL MW: OBL NCNE: OBL |
MN county distribution (click map to enlarge): | |
National distribution (click map to enlarge): |
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Detailed Information
Flower:
Pinkish purple flowers whorled in a dense cluster around the stem at the leaf axils. Flowers have 4 to 7 crinkled petals (usually 5), each about ¼ inch long, elliptical but often fleeting and not always easy to distinguish. 8 to 10 white-tipped pink stamens arch out in a spidery array extending nearly double the length of the petals. Over-all flower structure is nearly 1 inch across.The calyx holding the flower is a thin walled, paper-like cup with gnarly appendages. Multiple flowering stems, rarely branched, shoot from the base of the plant.
Leaves and stem:
Leaves are opposite or more often in whorls of 3 or 4, elliptical to lance-like, tapered similarly at both ends, 2 to 8 inches long, ½ to 2 inches wide, toothless, finely hairy on the underside and smooth on the upper surface, the mid-vein reddish near base, on a short stalk. Stems are long and arching, up to nearly 10 feet in length but the overall plant height rarely exceeds 3 to 4 feet. Stems root at the tips as they re-meet the substrata, are sometimes slightly hairy, angled with 4 to 6 sides, often pinkish red on blooming canes and woody at the base.
Fruit:
Fruit is a globular capsule up to 1/3 inch across, containing numerous seeds. Capsules persist through winter. Minnesota plants rarely form set seed but spread as clonal mats via re-rooting stems.
Notes:
Being at the northwest fringe of its natural range, Swamp Loosestrife is restricted to lakeshores in east central Minnesota. Because this region has seen such heavy development over the past decades it should come as no surprise that another native species has been put at risk. According to the DNR it has been listed as a Special Concern species since 1984.Native Plant Nurseries, Restoration and Landscaping Services ↓
More photos
- Swamp Loosestrife plants
- Swamp Loosestrife habitat
- more plants
- more flowers
- sprouting plants in shallow water
- still more flowers
Photos courtesy Peter M. Dziuk taken at several locations in Anoka county.
Comments
Have you seen this plant in Minnesota, or have any other comments about it?
on: 2016-10-29 15:40:39
How can I tell this apart from purple loosestrifge
on: 2016-10-29 16:17:12
Flowers are arranged differently: Decodon verticillatus has flowers whorled in the leaf axils, Lythrum salicaria has a single spike at the tip of a branch.
on: 2017-09-12 15:38:03
There is a creek that runs through our property called Spirit Creek which runs into the Rum River. The creek is the outlet for Long Lake. This plant is massive, almost to the point of chocking out the creek. Now this year, it has spread onto our shoreline in front of our home on Long Lake. A few years ago I checked with DNR and they said this is the farthest west that they have seen this plant.
on: 2018-08-18 11:43:13
It is on our shoreline on Knife lake
on: 2020-07-01 10:55:50
on: 2020-07-05 12:21:44
At the northern boat landing in Monticello. New landing put in. Many wildflowers.. I have seen this about four feet from shore.
on: 2023-08-05 12:28:26
Big Blake Lake, WI - in a narrows - it covers both sides. Beautiful!
on: 2023-09-23 18:47:58
Lovely large stand at the inlet creek to Chub Lake
on: 2023-09-29 14:41:32
A small island in the St. Croix River near the mouth of the Kettle River has a patch of this plant covering about 300 square feet. Over 30 years ago I saw it there, without knowing of it's rarity.