white snakeroot

(Ageratina altissima var. altissima)

               
Conservation Status

IUCN Red List

not yet assessed

white snakeroot

NatureServe

N5 - Secure

SNR - Unranked

Minnesota

not listed

Wetland
Indicator
Status

Great Plains

UPL - Obligate upland

Midwest

OBL - Obligate wetland

Northcentral & Northeast

OBL - Obligate wetland

Nativity

Native

Photo by Kirk Nelson
Occurrence

Common

 
Habitat

Moderate moisture. Woodland edges and openings, trailsides. Shade.

 
Flowering

Late July to September

     
Flower Color

White

     
Height

1 to 5

     

Identification

This is a 1 to 5 tall perennial forb that rises on 1 to 3 stems from a rough, knotty, fibrous-rooted rhizome. It grows only in shade. It is a late bloomer, one of the last flowers to be seen in the woods in the fall.

The stems are erect or ascending, branched near the top, leafy, and hairless or covered with fine, short hairs.

The leaves are opposite, thin, and egg-shaped to broadly lance-shaped. They gradually taper from above the base to a sharp, drawn-out point forming concave sides along the tip. The bases are often rounded or heart-shaped. They are on ½ to 2½ long leaf stalks. The blades are 1½ to 5 times longer than the leaf stalk. The lower leaves are 2 to 6 long and 1 to 5 wide, becoming gradually smaller as they ascend the stem. They have 9 to 25 sharp teeth on each margin. The upper surface is mostly hairless, the lower surface hairy along the veins.

The inflorescence is a flat-topped to dome-shaped branched cluster. On smaller plants they are compact and appear at the end of each upper stem. On larger plants they are open and also appear on long stalks from the upper leaf axils. The clusters are up to 3 wide and have many flower heads.

Each flower head is about ½ wide and ¼ tall. It contains 12 to 25 disk florets and no ray florets. Each disk floret is about ¼ wide, consisting of a bright white flower tube with 5 long spreading lobes. A white, forked style protrudes from the floral tube well beyond the lobes.

The fruit is a tiny dark achene with a small tuft of white hairs about long.

 
Similar
Species

Common boneset (Eupatorium perfoliatum var. perfoliatum) leaves are longer, narrower, stalkless, fused around the stem at their bases. The flower heads are much smaller. It is usually found in full sun, in prairies and meadows, often in wet areas.

Tall boneset (Eupatorium altissimum) leaves are mostly stalkless or are attached to the stem on short leaf stalks. The flower heads are much smaller. Each flower contains just 5 disk florets. The fruit has a tuft of light brown hairs. It is usually found in full sun, in prairies and meadows.

 
Pests and Diseases

Leaf miner fly (Liriomyza eupatoriella)


Distribution Distribution Map   Sources: 2, 3, 4, 5, 7, 24, 28.

Comments

Taxonomy
This plant has recently been reassigned to the genus Ageratina. Most sources, both in print and online, still refer to it using its old name Eupatorium rugosum.

Toxicity
This plant is poisonous to livestock. If eaten by cows their milk may also be poisonous to humans. It was unusually abundant in southern Minnesota in 2004. A number of horses in the New Ulm area died in the summer of that year, and it is thought that white snakeroot is the cause.


Taxonomy

Family:

Asteraceae (aster)

 

Subfamily:

Asteroideae

 

Supertribe:

Helianthodae

 

Tribe:

Eupatorieae

 

Subtribe:

Oxylobinae

 
Synonyms

Ageratina altissima var. angustata

Ageratina altissimum

Eupatorium rugosum

Eupatorium rugosum var. chlorolepis

Eupatorium rugosum var. tomentellum

Eupatorium rugosum var. villicaule

Eupatorium urticifolium

Eupatorium urticifolium var. tomentellum

 
Common
Names

common white snakeroot

richweed

snakeroot

snow thoroughwort

white sanicle

white snakeroot


 

 

 

 

 

 

 

 

 

 

Glossary

achene

A dry, one-chambered, single-seeded fruit, formed from a single carpel, with the seed attached to the membranous outer layer (wall) only by the seed stalk; the wall, formed entirely from the wall of the superior ovary, does not split open at maturity, but relies on decay or predation to release the contents.

 

rhizome

A horizontal, usually underground stem. It serves as a reproductive structure, producing roots below and shoots above at the nodes.

       

Visitor Photos

   
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Kirk Nelson


Along the edge of the woods near the beach parking area.

  white snakeroot   white snakeroot
       

Lost Valley Prairie SNA, Washington County

  white snakeroot    

       
       
       

MinnesotaSeasons.com Photos

   

Habitat

  white snakeroot    
       

Plant

  white snakeroot   white snakeroot
       

Inflorescence

  white snakeroot   white snakeroot
       
  white snakeroot    
       

Flower Heads

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Leaves

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Camera

     

Slideshows

   
  White Snakeroot (Ageratina altissima)
Bill Keim
 
  White Snakeroot (Ageratina altissima)  
     
  Ageratina altissima (White Snakeroot)
Allen Chartier
 
  Ageratina altissima (White Snakeroot)  

 

slideshow

     

Visitor Videos

   
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Other Videos

 
  Minnesota Native Plant - White Snakeroot (Eupatorium Rugosum)
MNNativePlants
 
   
 
About

Published on Aug 29, 2013

This video is of the White Snakeroot (Eupatorium Rugosum), a beautiful native white flower that blooms in late summer.

 
     
  Dark Energy Medicinal Plant: White Snakeroot
Living the Hedge Witch Life
 
   
 
About

Uploaded on Aug 17, 2011

A toxic plant, white snakeroot has a medicinal value in bringing a person out of a faint or stupor with the smoke. The plant, however has caused the death of many a person through milk sickness--a poisoning where a milk animal ingests the poisons of the plant and then a person drinks the milk, now containing the toxin.

 
     

 

Camcorder

         

Visitor Sightings

   
Share your sighting of this plant.

Kirk Nelson
8/19/2017

Location: Fort Snelling State Park

Along the edge of the woods near the beach parking area.

white snakeroot


Kirk Nelson
9/14/2014

Location: Lost Valley Prairie SNA, Washington County

white snakeroot


     
     
 

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