South Dakota Native Plant Research
Asteraceae : Ageratina altissima

Asteraceae : Ageratina altissima


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Family Name


Common Name

White snakeroot


Ageratina altissima is a perennial herb arising from a rhizome, with upright or sometimes ascending stems, covered with short spreading hair, growing from 30 to 150 cm tall. The simple, opposite petiolate leaves have blades that are ovate to broadly ovate, contracted at the base and pointed at the tip, 6-15 cm long and 3-12 cm wide toward the base and smaller toward the top, with variously toothed margins. Each pair of leaves is positioned at a 90-degree angle from the pair above and below. The inflorescence is made up of flat-topped clusters of heads. Each head has a 3-5 mm involucre of bracts that are all about the same length. There are 12-24 white disk flowers that produce 5-sided achenes that have a bristly pappus and, when mature, appear as fluffy white balls like dandelions and seeds are carried in the wind. White snakeroot blooms in August through October in open woods and disturbed sites in eastern and south-central parts of South Dakota.

Additional Notes

White snakeroot is an attractive addition to a native plant garden with its long-blooming clusters of delicate white flowers that attract butterflies. Be aware that white snakeroot is poisonous if eaten. As the name implies, it was once used to treat snakebite.

Horticulture Notes

Seed Collection:Collect seed in late summer or early

Seed Collection: Collect seed in the fall, when they begin to be released. Germination: Fall sow or give 60-day cold treatment before spring sowing. Vegetative Propagation: Division of rhizomes in the spring. Soils: Well-drained soils of most types’ Light: Partial shade
Water: Medium wet to medium dry.

Asteraceae : Ageratina altissima