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Weed Identification

white snakeroot

Family

Asteraceae

Scientific Name

Ageratina altissima

Other Common Names:

richweed
snakeroot

Synonyms (former Scientific Names):

Eupatorium urticifolium
Ageratum altissimum
Eupatorium rugosum

Habit

A perennial plant with erect stems that can grow up to 5ft tall in a season. Flowers typically bloom in the fall.

Leaves

Leaves are opposite; ovate and serrated along the margins. The base of the leaf is rounded. Leaves may have hairs on the underside.

Identifying Characteristics

An erect perennial herb with clusters of small, white flowers. Leaves have a wide, rounded base and have serrated margins. The underside of leaves are often hairy, especially along the central vein. This species is toxic to humans and other mammals.

Flower Seed Head

The small white flowers (3-6mm) are not showy and occur in clusters on the terminals of erect branches.

Seed Fruit

Fruit is an oblong achene that has a little tuft of hair (papus) on one end.

Where Found

Typically found in woods, meadows, and along roadsides.

Growth Habit

upright and nonwoody

Thorns or Spines

not present

Approximate Flower Diameter

pencil

Dominant Flower Color

white

Flower Symmetry

not symmetrical

Leaf Hairs

Varies: 
has hairs
no hairs

Leaf Shape

oval

Leaf Arrangement

opposite

Leaf Margin

serrated

Leaf Structure

simple

Leaf Stalk

Varies: 
shorter than leaf
longer than leaf

Stem Hairs

no hairs

Stem Cross Section

round or oval

Milky Sap

not present

Root Structure

Varies: 
fibrous
taproot

Life Cycle

perennial

Ochrea

not present

Plant Type

Herb