Ageratina altissima (L.) R.M. King & H. Rob.

White snakeroot, tall boneset, white sanicle

About plant names...

White snakeroot is native to eastern North America.

Plants: Up to 5' (1.5 m) high, growing as a single plant or a clump with multiple stems. Stems are light green, some­times tan, round, with few or no hairs.

Leaves: Near the base of the plant, leaves are are heart-shaped to oval (cordate to cordate-ovate). Leaves further up the stem are narrower and more lance-shaped (lanceolate). The leaves are 2½-6" (6.3-15 cm) × 1-3" (2.5-7.6 cm), with sharp, coarse serrations. Leaf undersides have prominent veins. Leaf stems are longer than most, from ½-2½" (1.3-6.3 cm) long.

Flowers: White snakeroot blooms in rounded corymbs, each containing 10 to 25 white flowers about ⅛" (5 mm) around. Each flower is a composite flower, composed of a central disc and surrounding petals. Since each petal is technically a flower in its own right, you could say that white snakeroot contains flowers within flowers within flowers. Or petals and disc flowers within flowerets within inflorescences. Or just white fuzzy-looking flowers.

Fruits: Tiny black bristled 5-angled achenes equipped with equally tiny parachutes.

Edibility: Poisonous Plants contain tremetol and glycosides, which together cause staggers, a potentially fatal disease in cows. These plants are also toxic to people, and milk from cows exposed to white snakeroot can also cause illness called “milk sickness” in people. In the 1800s, when drought sometimes forced cows to forage in forests for food, this caused extensive deaths.

Online References:

Ageratina altissima at Illinois Wildflowers

Ageratina altissima on Kansas Wildflowers and Grasses

Ageratina altissima on Southeastern Flora, the Southeastern U.S. Plant Identification Resource

Ageratina altissima at Minnesota Wildflowers

Ageratina altissima on the Connecticut Botanical Society's Connecticut wildflowers site

Ageratina altissima on Plants for a Future, a resource and information centre for edible and otherwise useful plants

Ageratina altissima on www.pinecreekvalley.com

Ageratina altissima on Discover Life

8/6/2010 · Nashua River Rail Trail, Groton, Mass­a­chu­setts
≈ 15 × 16" (37 × 41 cm) ID is uncertain

8/15/2013 · Groton Place and Sabine Woods, Groton, Mass­a­chu­setts
≈ 9 × 6" (22 × 15 cm)

8/6/2010 · Nashua River Rail Trail, Groton, Mass­a­chu­setts
≈ 15 × 22" (37 × 56 cm) ID is uncertain

9/7/2013 · Beech Hill, Dublin, New Hamp­shire
≈ 10 × 7" (25 × 16 cm) ID is uncertain

9/7/2013 · Beech Hill, Dublin, New Hamp­shire
≈ 8 × 5" (19 × 12 cm) ID is uncertain

8/15/2013 · Groton Place and Sabine Woods, Groton, Mass­a­chu­setts
≈ 8 × 6" (19 × 14 cm)

10/2/2010 · Hackers Trail, Cliff Park, Delaware Water Gap National Recreation Area, Penn­syl­vania
≈ 7 × 4½" (17 × 11 cm)

Ageratina altissima description by Thomas H. Kent, last updated 5 Oct 2021.

© FloraFinder.org. All rights reserved.

8/6/2010 · Nashua River Rail Trail, Groton, Mass­a­chu­setts
≈ 4½ × 3" (11 × 7.5 cm) ID is uncertain

8/6/2010 · Nashua River Rail Trail, Groton, Mass­a­chu­setts
≈ 9 × 12" (22 × 31 cm) ID is uncertain

9/7/2013 · Beech Hill, Dublin, New Hamp­shire
≈ 5 × 8" (13 × 20 cm) ID is uncertain

8/15/2013 · Groton Place and Sabine Woods, Groton, Mass­a­chu­setts
≈ 11 × 7" (28 × 18 cm)

12/12/2020 · By Jacquelyn Boyt

8/15/2013 · Groton Place and Sabine Woods, Groton, Mass­a­chu­setts
≈ 9 × 6" (23 × 15 cm)

10/2/2010 · Hackers Trail, Cliff Park, Delaware Water Gap National Recreation Area, Penn­syl­vania
≈ 9 × 6" (23 × 15 cm)

8/31/2021 · Pumpkinvine Nature Trail, Middlebury, Indi­ana · By Jeff Griffin

8/6/2010 · Nashua River Rail Trail, Groton, Mass­a­chu­setts
≈ 8 × 12" (21 × 31 cm) ID is uncertain

10/2/2010 · Hackers Trail, Cliff Park, Delaware Water Gap National Recreation Area, Penn­syl­vania
≈ 4 × 4" (10 × 10 cm)

Range: Zones 4-8:

About this map...