Beware: Poison Plants Ahead

With all of nature’s beauty it has a nasty side. Along with the myriad of beautiful plants come a few of which you should be aware. On your treks through the woods pay attention to those that can poison you and your pet through touch, smell, and taste. Here are some commonly occurring poison plants that we need to avoid.

Poison Hemlock (Conium maculatum)

Plants of Texas Rangelands credit

As with many non-native plants, folks in the 1800s brought over poison hemlock from Europe as an ornamental “winter fern”. Since then, it has spread across the United States along roadsides, through fields, and finally making its way into grazing pastures. Most livestock avoid it due to its unpleasant smell and taste. Most people confuse it with Queen Anne’s Lace, picked for its tiny white flowers to adorn floral arrangements. 

The differences are subtle, but noticeable. Poison Hemlock grows up to 10-feet tall with a hairless, spotted purple stem. Queen Anne’s lace reaches a mere 3-feet with a hairy, spotless green stem.

Nature has given us two other plants similar to Queen Anne’s lace:

wild parsnip (Pastinaca sativa)

Leslie J. Mehrhoffcredit

water hemlock (Cicuta maculata or Cicuta douglasii)

Thomas Barnes. credit

All look like wild carrots, parsnips, or parsley. Several wild plant foragers have died by misidentifying these plants. If you cannot tell the differences, leave them be!

All three are deadly poisonous. The root, seeds, leaves, and fruit contain alkaloid toxins. Just touching the plant causes skin irritation. Ingesting even small amounts causes severe reactions within 30 minutes. If you experience erratic symptoms after eating a plant or herb, seek emergency medical attention. Symptoms include Central Nervous System Depression and acute respiratory failure.  Depending upon the amount ingested, palliative treatment is available. However, there is NO antidote.

Poison Ivy (Toxicodendron radicans)

Poison Oak (Toxicodendron rydbergii)

Poison Sumac (Toxicodendron vernix)


The first thing to notice is that all the names begin with Poison. Scientifically, they all belong to the genus Toxicodendron, the Greek word for toxic tree. The toxin comes from the plant oil urushiol (you-ROO-shee-aal).

The evil of these is that you do not have to touch the plant. If the oil rubs off on your pet, your shoes, or anything else, it can still contaminate you. Most people who come in contact with this oil develop a rash in a few days. The itchy rash may form blisters lasting up to a few weeks. Worse still, when burned, the smoke contains urushiol. When mowed the oil becomes airborne. Inhaling this can cause severe breathing problems.

You have heard the saying, “Leaves of three, let it be”. That is a good general rule for identifying poison ivy and oak. Both are pervasive across America in backyards, parks, wetlands, forests, and the roadside. To confuse matters more nature gives us two varieties of each: Eastern and Western Poison Ivy and Atlantic and Pacific Poison Oak. It really does not matter as they all have similar looks and the same ill effects.

How to identify them

Poison Ivy begins with a rope-like vine that climbs trees, adorns fences, or snakes along the ground. The vine sprouts stems that culminate into clumps of three distinguishable heart-shaped leaves. The leaves are glossy green turning yellow and red in the fall. In spring and fall they may develop pale berries of yellow or white. 

Poison Oak differs only in that it grows into a shrub of 3-10 feet tall rather than a vine. Its leaves are oak-like in shape. This insidious plant blends in with the surrounding foliage by changing seasonal colors. It culminates with clusters of green-yellow or white berries.

Poison Sumac grows into a shrub of 5-10 feet with drooping branches. Its leaves are parallel on the stem and opposite one another ending in a single leaf at the tip. They are oval in shape with a sharply pointed end tip. In spring it develops tiny white flowers that turn into pale berries in the fall. It thrives at low elevations in wet or frequently flooded areas.

Treatments for exposure

Should you become exposed to any of these there are treatments that can minimize the ill effects. First, wash all clothing in hot soapy water. Next, shower away as much urushiol as possible with warm soapy water. This will reduce the likelihood of an allergic reaction.  

If a rash develops, soak in a cool bath using an oatmeal-based product. Most importantly, ask your pharmacist to recommend creams designed to reduce the itchiness. See your doctor is you get a fever of 100*F plus, the rash becomes inflamed, or the itching gets worse. 

Whether hiking the trails, exploring the forest, or pulling weeds in my own backyard, I am always plant alert. If I am uncertain of what that vine, shrub, or pretty white flower is, I try to identify it with iNaturalist. I also call on my local county extension agent. Better safe than sorry.

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