Minnesota Wildflowers


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Ageratina altissima (White Snakeroot)

Plant Info
Also known as:
Genus:Ageratina
Family:Asteraceae (Aster)
Life cycle:perennial
Origin:native
Habitat:part shade, shade; thickets, deciduous woods
Bloom season:July - October
Plant height:1 to 4 feet
County distribution (click map to enlarge):Minnesota county distribution map
Spotted in Ramsey County at:

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Detailed Information

Flower: indistinct flat

[photo of flowers] A few to many small flower heads in numerous flat clusters 1 to 2 inches across at the end of branching stems. Flower heads are made up of 10 or more bright white 5-parted disk flowers, each about 1/6 inch across, with protruding white styles. There are no ray flowers (petals).

Leaves: opposite simple

[photo of leaves] Leaves are 2 to 6 inches long, 1 to 4 inches wide with coarse teeth all around the edges, a sharply pointed tip, and slender leaf stalk up to 2½ inches long. The leaf base is typically wide and rounded or somewhat heart-shaped, becoming more tapered as they ascend the stem. The underside of leaves are typically hairy along major veins. Stems are green and mostly hairless.

Fruit:

[photo of fruit] Flower heads transform to black seeds with silken parachutes attached to carry them away.

Notes:

When I took a walk through the park in mid-September, the woods there were filled with White Snakeroot. It and Canada Goldenrod were about the only things blooming in the woods. The flowers are similar to Boneset, and in fact White Snakeroot used to be in the same genus (Eupatorium rugosum) but has since been reclassified. The leaves are distinctly different between the Eupatorium species and White Snakeroot, so a positive ID is fairly easy.

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Map of native plant purveyors in the upper midwest

More photos

Photos by K. Chayka taken at Long Lake Regional Park, New Brighton, MN, July and September 2006 and August 2009. Other Photos courtesy Peter M. Dziuk taken in Anoka county.

Comments

Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Carrie Anne in Minneapolis, MN
on: 2010-08-19 14:45:30

Having just positively identified this as growing in my yard, I also went to do a little more research on it. I learned something very important! It contains tremetol, a toxin that has killed humans (notably Abraham Lincoln's mother), when passed on from cow's milk. There are more details on "milk sickness" here at: http://en.wikipedia.org/wiki/Milk_sickness. I think this is very important to note as I have a 3 yr old, but I also want to maintain native plants in my yard, and now I will know to keep an eye on him around this plant.

Posted by: Mary Beth in Twin Cities
on: 2010-08-28 11:52:11

Many non-native garden and house plants are also toxic when ingested - lilies of the valley, azaleas, hydrangeas. However, white snakeroot has been used to treat snakebite. I taught my son not to touch any plant until he learned which ones were safe.

Posted by: Lisa in Coon Rapids
on: 2011-09-14 08:58:06

This showed up in my yard this summer.

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