white snakeroot

(Ageratina altissima var. altissima)

Conservation Status
white snakeroot
Photo by Kirk Nelson
  IUCN Red List

not listed

     
  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

     
           
 
Description
 
 

White snakeroot 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.

 
     
 

Height

 
 

1 to 5

 
     
 

Flower Color

 
 

White

 
     
 

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.

 
     
 
Habitat
 
 

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

 
     
 
Biology
 
 

Flowering

 
 

Late July to September

 
     
 

Pests and Diseases

 
 

white snakeroot leaf miner (Liriomyza eupatoriella)

 
     
 
Use
 
 

Faunal Associations

 
 

 

 
     
 

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.

 
     
 
Distribution
 
 

Distribution Map

 

Sources

2, 3, 4, 5, 7, 24, 28.

 
  12/31/2013      
         
 

Nativity

 
 

Native

 
         
 

Occurrence

 
 

Common

 
         
 
Taxonomy
 
  Kingdom Plantae (green algae and land plants)  
  Subkingdom Viridiplantae (green plants)  
  Infrakingdom Streptophyta (land plants and green algae)  
  Superdivision Embryophyta (land plants)  
  Division Tracheophyta (vascular plants)  
  Subdivision Spermatophytina (seed plants)  
  Class Magnoliopsida (dicots)  
  Superorder Asteranae  
 

Order

Asterales (sunflowers, bellflowers, fanflowers, and allies)  
 

Family

Asteraceae (sunflowers, daisies, asters, and allies)  
  Subfamily Asteroideae  
  Supertribe Helianthodae  
  Tribe Eupatorieae (bonesets, blazingstars, and allies)  
  Subtribe Oxylobinae  
  Genus Ageratina (snakeroot)  
 

Species

Ageratina altissima (white snakeroot)  
       
 

This plant was formerly named Eupatorium rugosum.

 
       
 

Subordinate Taxa

 
 

 

 
       
 

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

 
 

Fort Snelling State Park. 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

 
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Inflorescence

 
    white snakeroot   white snakeroot  
           
    white snakeroot      
           
 

Flower Heads

 
    white snakeroot   white snakeroot  
           
 

Leaves

 
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    white snakeroot      
           

 

Camera

     
 
Slideshows
 
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
 
           
 

Report a sighting of this plant.

 
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Simply email us at info@MinnesotaSeasons.com.
Be sure to include a location.
 
  Brandon Artmann
8/28/2021

Location: near Scherman, MN

Abundant in our woods, near Scherman, MN, especially along wood edges.

 
  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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