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Eight Common Plants that have Dangerous Traits

By Bob Fitz, PLA, ASLA, Principal, Koontz-Bryant, P.C.

Most people are familiar with the hazards of handling some of the more commonly known plants such as poison ivy, poison oak or poison sumac.  Adverse reactions can include mild to severe rashes, swelling and itching.  However there are quite a few other plants that we are likely to come in contact with that that could pose much more serious consequences.  Here is a list of 8 dangerous common plants you should be aware of:

Oleander (Nerium Oleander)

Oleander is one of the most poisonous of all commonly grown garden plants, and though it's especially toxic to children it is often planted in school yards.  It is a vigorous bush and grows on many different continents but usually in the more temperate areas.  It has beautiful, fragrant blossoms, and is often included in gardens or commercial landscapes.  Most people do not realize that touching or tasting the leaves or stems can be perilous.

A small child can experience symptoms after handling just one leaf from the plant, though typically it takes more contact for severe reactions to take place. Upon consumption, the poison causes intestinal issues like vomiting, diarrhea, excess salivation, weakness and cramping/pain. It can also cause a racing, irregular/increased heart rate, poor circulation, tremors, seizures, coma, and death.

Water Hemlock (Cicuta)

Water Hemlock can be found throughout North America, usually appearing in marshy areas like wet meadows and along stream banks.  Called “the most violently toxic plant in North America” by the USDA, it is the plant's roots that contain the deadly sap that, when touched or eaten in a threshold dose, can cause grand mal seizures and death.

A very poisonous alkaloid and a resinoid toxin are found in all parts of the spotted water hemlock, but primarily in the roots. The pithy area between the nodes contains greenish yellow oil, which contains the toxins.  Livestock and humans are especially susceptible to this poison. The plant grows in wet, damp soil, which enables animals to easily pull up the plant. Most livestock poisoning cases occur in the springtime; children have been poisoned by making “pea-shooters” from the hollow stem segments.

English Yew (Taxus Baccata)

With the exception of the berries, all of the plant is toxic.  Consumption of the Yew in even tiny amounts causes cardiac issues that may result in death.  It is quick-acting and there is no antidote.  Children are often attracted to the fruits.

Various species of this evergreen shrub are commonly planted as an ornamental shrub or hedge.  The fruit is a bright red, fleshy, translucent cup surrounding a large seed.  The leaves, bark and seeds of the plant contain the alkaloid, taxine, and thus are deadly.  The red pulp of the fruit is not particularly toxic, but the seed must be avoided.  Unbroken it will pass through the body without being digested but if the seed is chewed poisoning can occur with as few as three berries.   Symptoms are nausea, circulatory failure and depressed respiration. 

Dumb Cane (Dieffenbachia)

A common shade-loving household plant, Dumb Cane is a tropical plant that is among the most toxic plants in the world.  With common names like Dumb Cane, Mother-in-Law’s Tongue and Dumb Plant, you can be sure that this plant has an interesting story associated with it.  It has been known for over a century that if any part of it is eaten a sudden burning irritation and paralysis of the mouth, tongue, and lips will result.  This usually prevents a person from talking for a while, which has led to the amusing common names.  However, ingestion of this leafy plant causes intense pain in the mouth and throat, excessive salivation, and in rare cases, severe swelling of the throat that can lead to strangulation.  


Jimson Weed (Datura Stramonium)

The very first plant poisoning death in the United States is credited to this little weed:  Jimson weed.  The Jamestown, VA settlers used Jimson weed to poison British soldiers, who then spent 11 days in a state of insanity until they came to their senses (and didn't remember a thing).  Turns out those soldiers got off easy; symptoms such as abnormal thirst, vision distortions, delirium, incoherence, and coma are often fatal.  Also called devil's trumpet, angel's trumpet, devil's weed, stinkweed, locoweed, and hell's bells, people who attempt to consume this weed recreationally for the hallucinogenic properties often get more than they bargain for because it's nearly impossible not to overdose.  The phrase "Red as a beet, dry as a bone, blind as a bat, mad as a hatter" has been used to describe Jimson's effects, and it does a good job of summing them up.  Jimson weed grows wild all over the world in cultivated gardens and fields, waste areas, barnyards, abandoned pastures, and roadsides. 

Mistletoe (Phoradendron serotinum)

While kissing under the mistletoe is perfectly acceptable, eating the plant or its berries is not.  The white berries of this familiar Christmas ornament are considered to be poisonous.   Ingesting them can cause acute gastrointestinal problems including stomach pain, and diarrhea along with low pulse.  Eating any part of the plant or drinking a tea made from the plant can result in sickness and depending upon the type of mistletoe, possibly death.


Virginia Creeper (Parthenocissus quinquefolia)

Virginia creeper is often confused with eastern poison ivy; however, a clear distinction between the species is that eastern poison ivy has three leaflets and Virginia creeper has five leaflets.  Virginia creeper berries are highly toxic to humans and may be fatal if eaten.  Fruits are purplish-black berries; about 1/4 inch across and its sap can also cause skin irritation in some people.  Virginia creeper can grow just about anywhere in shade or sun.  It can be found in forests, fields, gardens, and along banks of streams or lakes.  It is often used as a ground cover to control soil erosion in shaded areas and on slopes. 

Wild Cherry (Prunus serotina)

Mature trees can grow to 30 ft. or more, but also grows as shrub.  The wilted leaves and new twigs contain the highest cyanide levels but the bark is also poisonous.   Cyanide prevents blood from releasing oxygen to the tissues and can cause respiratory distress and even sudden death.  For most species of cherry, the fruit is safe for consumption.  It is the leaves and bark which pose the greatest risk.  Consumption of damaged or wilted leaves is a particular hazard to livestock.  Pets should not be housed or confined in the vicinity of cherry, since boredom will increase the likelihood that the plant will be eaten.



While most people are not in the habit of consuming native vegetation or ornamental landscape plants there still needs to be awareness that ingestion and/or contact of seemingly harmless plants, particularly by children, small pets or livestock, can have serious consequences.  When creating, renovating  or adding to the landscape, the right types of plants should be used that are appropriate for the end use (ex;  playgrounds, day care facilities, parks, public spaces, private gardens, etc.)  Contact Bob Fitz at Koont-Bryant, P.C for any further questions or landscape design assistance.

Sources include:  USDA, FDA, CDC, Extension Services of: Virginia Tech, NCSU, WVU