White Snakeroot Plant: Toxicity and Why You Should Avoid It

When it comes to foraging, there are always plants out there that are important to recognize, but better left alone. On the top of any homesteader’s “hands off” list should definitely be white snakeroot.

This plant, while it does have some purported medicinal uses, is a plant best left alone, or limited to some plantings in naturalized woodland gardens, alongside ostrich ferns and wild ginger. Knowing some of the history and lore of this plant can definitely make you stand out amongst other homesteaders, though!

Ageratina altissima flowers
By Sten Porse – Own photo, taken in Jutland., CC BY-SA 3.0, Link

White snakeroot (Ageratina altissima) is a late-blooming weed that can go largely unnoticed until fall. The fluffy white flowers bloom from late July to September. It was once known as Eupatorium rugosum, and it is often still referred to by this name despite now being in the Ageratina genus.

Although “weeds” don’t have the best reputation, white snakeroot provides much-needed food and nutrients to foraging insects such as bees who need to plump up before the winter freeze.

But humans should be warier, and the plant had a reputation among Native Americans and English settlers in the eastern United States and Canada as a poison.

Although white snakeroot is not popular among foragers, due to its toxicity it is important to be able to differentiate it from other, possibly edible plants.

There are look-alike plants with medicinal and edible properties for which snakeroot can be mistaken. However, the perennial is essential to small wildlife, such as bees and birds, even though it has a fatal history with humans.

That being said, it can make a delicate addition to any garden, so long as you take caution. Here’s a great overview of white snakeroot, an important plant you likely have growing in the forests around your homestead.

Where to Find Snakeroot

White snakeroot grows in the eastern half of North America, from southern Canada to northern Texas. The weed does best in shaded areas, such as forests, mountain ranges, and under natural rocks. Snakeroot is common in suburban and urban areas.

You can find it along shady sidewalks and public parks. It prefers moist, alkaline soil, so you most likely won’t find it in the deep south. But you’ll definitely find some along waterways and windbreaks in Ohio and Nebraska, or even in dense urban centers like Chicago and New York City.

White snakeroot is often found growing in areas that have been disturbed, such as now-vacant lots, roadsides, and even powerline clearances.


The perennial grows in hardiness zones 3-8. Hardiness refers to the ability of a plant to grow in certain climates. The continental United States is broken into 11 hardiness zones.

A hardy plant is one that can grow in several zones, while a tender plant is one that can only grow in a small range of zones. Thus, snakeroot is a hardy plant.

It’s no surprise that the perennial can grow in so many varying climates, when you consider that it blooms in forests and dense urban areas alike.

Hardiness Zone 3 in northern Minnesota has a minimum temperature between -30 and -40 degrees. Flowers that grow in this range include bee balm and asters.

Hardiness Zone 8 along the southeast coast has cool, mild winters. The average low temperature is between 10 and 20 degrees. Other plants that grow in zone 8 are dahlias and peonies.

How to Identify White Snakeroot

White Snakeroot that hasn’t flowered is nondescript. The small plant will usually be hiding in the shade, making it easy to miss while foraging.

However, if you examine the plant closely, there are structural identifiers along the leaves and stem, at least during summer. In the fall, you may see the fluffy white flowers everywhere.


White snakeroot is relatively small. The weed grows between two and four feet tall. The leaves typically grow 2-5 inches long and 1-3 inches wide.

The perennial’s small size makes it hard to notice until the flowers bloom. In autumn, the clusters of white flowers expand 1-2 inches from the ends of branching stems.


Snakeroot has dark green leaves that grow round with pointed tips at the ends. The leaves all grow opposite each other, so a plant with four leaves will have one pointing in each direction. The leaves are coarse toothed, meaning the edges are jagged rather than smooth.

The white flowers that bloom in autumn grow in tight clusters from branches extending from the stem.

If you look very closely at the tiny flowers, you’ll realize there’s actually quite a bit going on. Each flower head is composed of at least ten white five-parted disc flowers. Each flower is only ⅙ of an inch across and have protruding white styles.


The upper leaves of the white snakeroot plant are generally much bigger than the lower leaves and tend to be more oval-shaped. They have smooth edges and can grow up to 4 inches in length.

These larger leaves are also covered with fuzzy white hair which gives them their distinctive appearance. As they age, these hairs will begin to turn yellowish or brownish in color.

The lower leaves on the white snakeroot plant tend to be much smaller—usually no bigger than 2 inches in length—and have more of an egg-like shape with jagged edges.

Unlike their bigger counterparts, these smaller leaves do not have any hairs covering them, though they may have some very fine hairs along the veins on each leaf. The leaves have long petioles that are about an inch to two and a half inches in length.


White snakeroot produces black seeds that have silk-like parachutes to carry them away. These are quite pretty to look at, but the unique method of dispersal via the wind means that it’s incredibly easy for these plants to spread on your property.

In addition to spreading via seed, they can also propagate by underground stems or rhizomes.

Remove spent flower heads to prevent these plants from spreading where you don’t want them to!


White snakeroot weed has a few look-alike plants. Although snakeroot itself is not popular among foragers, it is still important to know how to identify it and differentiate it from similar-looking plants. You wouldn’t want to mistakenly forage for snakeroot while on the hunt for a medicinal or edible plant.

Common Boneset (Eupatorium perfoliatum)

Common Boneset (Eupatorium perfoliatum) is not popular in the kitchen. This perennial is emetic and a laxative in large doses. It can also cause damage to the liver.

However, it has several medicinal uses that make it popular among foragers. For example, boneset can treat fever, swine flu, joint pain, and constipation. Boneset grows in many of the same conditions as snakeroot. For example, it prefers moist soil in shady woodlands.

Common Boneset, like white snakeroot, is a small perennial with dark green leaves and small clusters of bright white flowers. At first glance, the two seem interchangeable, but if you look closer you will notice some key differences:

  • Common snakeroot has opposite leaf structure, and the lower branch will always grow horizontal, parallel to the ground, while the higher branch will be angled upward. Boneset, however, has perfoliate leaves, meaning they wrap around the stem.
  • The edges of snakeroot leaves have fine teeth, giving the leaf a jagged edge. Boneset leaves, however, are much longer and hairier.
  • Very fine, thin hairs grow along the stem of Boneset. You have to look very closely at the stem to notice the hairs. However, the hair growing along the stem of snakeroot is much thicker and more noticeable.

Wood Nettle

Wood nettle (Laportea canadensis) is another plant that can be hard to differentiate from snakeroot. Like snakeroot, wood nettle grows in woodland areas with moist soil. The plant is common in northern and central Illinois.

Unlike snakeroot, wood nettle is edible. Because snakeroot is not, so it is vital that foragers learn the differences:

  • The easiest way to tell these plants apart is by touching them. Wood nettle is a stinging plant. Like snakeroot, it has hairs growing along the stem. However, nettle’s hairs leave a burning and stinging sensation to all who touch it.
  • The leaves of both plants are serrated. However, wood nettle has an alternating leaf pattern, while snakeroot has an opposite pattern. Additionally, wood nettle leaves are a very bright, almost natural neon green. However, the leaves of snakeroot are much darker.
  • The flowers of wood nettle are greenish yellow. While snakeroot is famous for its bright white flowers.


White snakeroot weed is not edible. In fact, the leaves and stem contain tremetol, a complex alcohol that is poisonous to humans and animals. Although some Native American tribes used the roots for medicinal purposes, white snakeroot should be kept outside your body.

Furthermore, if you or an animal consume tremetol, symptoms of poisoning could take days to appear. This makes it all the more dangerous, as early detection is necessary for recovery.

The poison is usually detected through blood work in a laboratory. Humans can be treated in a hospital if the poison is detected early. Horses, however, can go through supportive therapy, but will never be cured.


Tremetol is an oil the yellowish color of hay. It is composed of a toxic mixture of keystones and unsaturated alcohols. The toxin is persistent, meaning it can build up in the body over time.

Once an animal consumes 5-10% of its body weight in snakeroot, it will begin exhibiting symptoms of tremetol poisoning. The poison is accumulative, meaning it will build up in the body over time.

Tremetol causes muscular degeneration, and it targets the most important muscle in the body: the heart. A human or animal poisoned with tremetol will experience tremors (hence the name of the toxin), irregular heartbeat, and ataxia. Untreated, symptoms will worsen until the poisoned individual passes away. However, it is treatable if detected early.

Milk Sickness

Tremetol poisoning is passed down through consumption, which means that any livestock that eats snakeroot will have tremetol in its meat or milk, and that any human who subsequently consumes these will also get sick.

During westward expansion, thousands of pioneers died from what became known as milk sickness. Food in the Illinois prairies could be sparse, so pioneers let their livestock graze on the local vegetation. However, the cattle consumed vast amounts of white snakeroot. The livestock started dying, as did the settlers who consumed milk from the poisoned cows.

Settlers soon began to notice a pattern. Livestock that fed freely in the woods were the ones who developed the sickness and passed it to the farmers. However, livestock that grazed in cultivated pastures had no such cases.

With the advice of a Shawnee woman, pioneer Anna Pierce identified white snakeroot as the culprit. However, her advice did not reach a wide audience. In 1840, one doctor incorrectly labeled poison oak and ivy. It wasn’t until the following decades that white snakeroot became widely known as the poisonous plant.

Anna Pierce discovered the poisonous properties of snakeroot by feeding it to a young calf. The calf died, however, the calves who fed on other plants did not. Thus, she was able to pinpoint it as the culprit.

Although she warned her local community, she did not receive any recognition from the wider medical community. Milk sickness was not eradicated until the early 20th century.

The Infamy of Milk Sickness

White snakeroot is perhaps the most infamous weed in American history. That is because Nancy Lincoln, Abraham Lincoln’s mother, died of milk sickness in 1818, only two weeks after moving to southern Indiana.

She had been caring for ill neighbors when she contracted milk sickness herself. Since the illness is not contagious or airborne, it is very likely she drank milk from one of their infected cows. The future President was only nine years old.

Snakeroot for Smaller Creatures

Although toxic to humans and animals, white snakeroot is vital to insects and small birds. The late-blooming perennial provides nutrition for bees, wasps, butterflies, and other pollinators before the winter freeze.

Snakeroot for a Variety of Insects

Unlike wasps, honeybees do not hibernate in winter. They survive freezing temperatures by generating their own body heat. However, as summer comes to an end, food becomes increasingly scarce. White snakeroot provides nutrition in autumn when other flowers are out of season.

Flies also lay their eggs on the plant’s leaves. After hatching, the larvae feed on the leaf, providing another important identifier if you’re not sure if a plane is snakeroot.

The larvae tunnel through the leaves, munching at the tissue. As they eat, the larvae leave long swirling trails through the leaves.

Snakeroot for Birds

Birds need food, water, and shelter wherever they are. While birds are known to migrate south for winter, many species do not. These nonmigratory birds need to be resourceful to survive harsh winter climates. Luckily for them, native plants provide much-needed nutrition and protection from the elements.

For example, the northern cardinal feeds on seeds and berries during the winter. The wind blows white snakeroot seeds throughout an ecosystem, and the seeds become an important food source for cardinals in winter.

Many gardeners are turning to snakeroot to provide winter habitats for local birds. However, you should not do this if you have pets or young children.

There is a legend that some tribes also used snakeroot roots to treat snake bites. Perhaps that is how the plant got its common name in the first place.

Supposedly, tribes in modern-day Virginia ground the weed’s roots into a poultice and applied it to snake bites as a salve. However, recent scientific studies have found no such properties in the perennial.

Snakeroot for Mammalian Herbivores

For the most part, herbivores will steer clear of snakeroot. It has such a bitter taste that they aren’t fond of munching on it.

That said, there have been instances in which cattle or other livestock will eat it in pastures that are overgrazed and when there are few other sources of food. This can produce detrimental results, so it’s a good idea to make sure your pastures are clear of white snakeroot before allowing your livestock to graze there.

Growing Snakeroot in a Garden

Although snakeroot can be fatal when consumed, many gardeners still choose to plant it in their gardens. The weed provides much-needed nutrition for local insects and birds, and can help reverse the decline of honeybee populations.

Not only that, but the beauty of this plant is another good reason for its cultivation in backyard gardens!

If you have an area of your yard that you’d like to give a more naturalized look to, white snakeroot may be the perfect candidate to add to a woodland garden consisting of native plants.

Growing Conditions

White snakeroot grows well in gardens that imitate its natural, wild habitat. This means that you should only plant it if you have naturally moist soil.

While the plant can tolerate full sun, it does best in areas with lots of shade. After all, the plant thrives in forests. If you don’t have a thicket to plant the snakeroot in, try planting it surrounded by larger plants, which will provide much-needed shade.

Alternatively, white snakeroot makes excellent natural decor for rock gardens. The delicate, cotton-like flowers provide a striking contrast to the hard shapes and sharp edges of rocks.

If you have ostrich or cinnamon ferns in your woodland garden, the contrast of white snakeroot’s leaves might make it the perfect companion plant. Similarly, mayapples, wild ginger, and jack-in-the-pulpit would complement a garden with some white snakeroot in it as well.

Snakeroot as an Invasive Species

One thing to look out for when planting white snakeroot is how quickly it can spread. The plant is prolific, and a windy day will cast its seeds across a wide area, where they will soon take root.

Additionally, this hardy plant can act as a ground cover and spread by fast growing rhizomes as well. Thus, if you aren’t careful, the plant can quickly become an infestation.

However, a snakeroot invasion can be easily prevented by digging up the root clumps, and dividing them in early spring before the plant flowers.

Parting Thoughts: A Useful Plant with a Colorful Past

Snakeroot, although inedible, is a useful plant that has played an interesting role in American history. Although snakeroot makes pretty additions to any garden, it might not be worth the trouble for gardeners with animals or young children.

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