Know Your Flora: Plants to Avoid when Traveling

Individuals who spend a lot of time outdoors can attest to the fact that there are plenty of toxic plants in the wild. Of course, a good way to avoid these species is to become familiar with their habits. The trouble is that these plants might not be as recognizable to some people as they are to others.  With that in mind, here are some details about the most poisonous plants in North America. Hopefully this information will help readers avoid any close encounters.

Poison sumac is a shrub that is native to the southern portions of the United States. It is commonly found in places with moist soil, such as swamps and bogs. As is the case with its relatives, poison ivy and poison oak, the urushiol contained in the plant’s leaves often causes painful rashes in sensitive individuals. The smoke from burned poison sumac bushes can also result in allergic reactions and further complications are possible if the plant toxins end up in one’s bloodstream. 

Pokeweed is native to the eastern portions of North America. It’s a shrubby perennial that gets about 8 feet tall and it produces darkly hued  berries. Although the leaves can be eaten if they are cooked in several changes of boiling water, pokeweed has proven deadly on several occasions. This is especially true in cases where children have eaten too many of the berries. However, improper preparation of the leaves has also caused adults to die on occasion. The root is nonetheless the most toxic part of this particular plant but even the sap has been known to cause contact dermatitis.

Lily of the Valley (Convallaria majalis) 

Lily of the valley is a popular garden ornamental and there is even a subspecies that might be native to North America. These perennials are widely known for their bell-shaped flowers, their light fragrance, and their lush green leaves. However, members of this species are highly toxic. Eating even the smallest amount can cause severe reactions. Children in particular have died from consuming the red berries produced by this plant. 

Oleander (Nerium oleander)

Originally native to the Mediterranean basin and parts of northern Africa, the hardy oleander plant has made its way around the world to naturalize in portions of the United States. Some sources state that consuming one oleander leaf is enough to prove deadly in adults. While this plant is known to contain toxic compounds and it has certainly been the cause of many calls to poison control centers, it has only been fatal in a few recent incidents. The sap is nonetheless a known skin irritant and honey that’s been contaminated by oleander nectar isn’t considered safe to eat. Snopes investigations have determined that there probably isn’t any truth in the urban legend about the boy scouts who died after using the plant as hot dog skewers. Even so, it certainly isn’t advisable to use oleander wood as any part of the cooking process.

Hemlocks (Conium maculatum and Cicuta species)

Water hemlock is widely considered one of North America’s most toxic native plant and its close relative, poison hemlock (shown above), has become naturalized here as well. These toxic species are members of the same family group as carrots, parsley, and parsnips. They even resembles them some degree. While there are certainly ways to tell the differences between hemlocks and wild edibles, these attributes aren’t always easy to pick out. The result is that hemlock species are occasionally eaten by mistake in what can end up being a fatal error. Rapid hospitalization of the victim in question is probably the best course of action. However, symptoms can show up as fast as fifteen minutes after eating the plant and death can quickly follow. Even individuals who survive being poisoned are likely to suffer lasting effects for quite some time afterward.  

Manchineel Tree (Hippomane mancinella)

This species is native to Florida and parts of the Caribbean. In populated areas, these ‘death apple’ trees are often tagged with red X marks or other signs to keep people away. After all, the manchineel is extremely toxic to human beings. Eating the fruit could result in a highly painful death but it is rare that anyone would get that close. Standing under this particular tree during a light rain can cause painful blisters to erupt on one’s skin. Its’ sap can also strip paint off cars. Exposure to the smoke from burned manchineel trees has even been known to cause serious lung and eye problems. With all that in mind, it’s not so surprising that the Carib Indians historically used byproducts from this tree to conduct chemical warfare against their enemies. 

Deadly Nightshade (Atropa belladonna)

Although nightshade was originally native to Europe, it has since naturalized in North America. This plant can be recognized by its dark, bell-shaped flowers and round berries. It grows best in damp, shady locations. Rubbing up against a nightshade plant can cause skin irritation, so proceed with caution if it turns up. Nightshade was once used as a medicine and as a cosmetic but, due to the plant’s toxicity, it has fallen out of favor on both counts. It was also historically used as a poison. While nightshade can certainly be deadly and fast-acting, the modern treatments available are fairly effective if they are administered in time. 

White Snakeroot (Ageratina altissima)

White snakeroot can be found in the eastern portion of the United States and in parts of Canada. This North American plant is often eaten by animals. People have then been poisoned from consuming tainted milk or meat from these same animals. This is believed to be what happened to President Abraham Lincoln’s mother, Nancy Hanks, along with thousands of other settlers. It was only much later that a Shawnee woman pointed out the plant to a doctor named Anna Bixby, who made the connection and undoubtedly saved a great many lives. It’s now rare that white snakeroot is a contributing factor in plant related deaths. However, its’ historical mortality rate cannot be denied. 

Castor Bean (Ricinus communis)

Castor bean plants are frequently seen as garden ornamentals. However, they have naturalized in certain places and currently grow wild in parts of California. This species is nonetheless a major allergy trigger. It is also poisonous and eating the seeds can have deadly consequences. There is some debate about how many of them it would take to kill a human being.  Britannica online reports that: “it only takes one or two seeds to kill a child and up to eight to kill an adult.”  Other sources state that just one bean is enough to kill anyone. A third source mentions that eating two or more beans is sure to make an adult sick but consuming eight or more will certainly cause death. However, the good news is that only a few fatalities have been reported because modern treatment is usually successful. While it’s certainly true that castor oil is made from this plant, the medicinal liquid must first undergo processing to remove the toxins and make it safe for human consumption.

Rosary Pea (Abrus precatorius)

Although they are native to India, rosary pea sare vining plants that have naturalized in many parts of the world. They are considered an invasive species in parts of the United States and especially in Florida. Rosary peas produce highly toxic black and red seeds which can be fatal to human beings if the seed coat breaks and releases the toxins within. This can obviously occur if the seeds are chewed up and eaten, in which case death is probably a foregone conclusion. However, poisoning can also take place if the person in question has come into contact with a cracked seed. 

Angels Trumpet (Datura species)

Angel’s trumpet goes by many different names. It is also known as jimsonweed, moonflowers, thorn apples, hell’s bells, and several other appellations. No matter what one calls these perennials, they remain popular garden plants despite their poisonous characteristics. Their striking appearance and their low maintenance reputation have probably contributed to this factor. However, eating the plants or eating contaminated honey made from the plants’ nectar can cause a wide variety of unpleasant symptoms. Erratic or delirious behavior and hallucinations are typical side effects. People who have been poisoned by this plant might also fail to remember anything that happened for some time after the fact. That certainly was the case with a group of British soldiers that were poisoned with this plant in Jamestown, Virginia. They survived but deaths have nonetheless been known to occur as a result of consuming angel’s trumpets, even in modern times.  

Dumb Cane (Dieffenbachia species)

Native to Mexico and the West Indies, dumb cane plantscontains poisonous compounds that can cause the tongue and throat to swell if the leaves are gnawed or eaten. This hasn’t prevented members of this genus from being popular houseplants. In fact, the showy leaves tend to make dumb canes an attractive prospect in that regard. Aside from rare cases where victims have asphyxiated from the swelling, being poisoned with this plant is not usually fatal. It still might be a good idea to keep dumb canes away from children or pets as these individuals usually don’t think twice before putting things in their mouths.

Moonseed (Menispermum canadense)

This climbing vine is native to both Canada and the United States. It can be found in damp woodlands and near flowing streams. Moonseed produces clusters of purple berries that ripen in the fall. They are often mistaken for wild grapes and subsequently eaten.. The main difference between moonseed and wild grapes is the shape of the seeds. Grapes produce round ones but those from the moonseed vine are shaped like crescents. Even so, it’s always best to avoid eating wild fruit to keep from making potentially tragic mistakes. Moonseeds can cause paralysis or even death. It just depends on how many have been eaten and how fast the victim in question can be gotten to a hospital. 

White Baneberry (Actaea pachypoda)

White baneberry is commonly found in North American forests. This perennial species stands several feet in height and is somewhat wider than it is tall. It typically grows in well-drained, shaded spots. It is also known as western baneberry, snakeberry, and doll’s eyes. The last appellation is no doubt because the plant produces white berries that are pierced by black stems. All parts of the white baneberry are toxic to human beings but the roots and berries are the most poisonous parts of the plant. 

Mountain Laurel (Kalmia latifolia)

Although it was originally native to parts of Europe, mountain laurel is an evergreen shrub that has since naturalized in eastern portions of the United States. The wood has historically been used to make a variety of crafts and the flowers are quite attractive. Even so, the plant is poisonous to human beings and several different animal species. Mountain laurel can prove deadly if the green parts of it are ingested. The plant’s nectar can also contaminate honey and make it inedible. However, this species isn’t the only type of poisonous laurel that can be found in North America.

Tobacco (Nicotiana species)

European immigrants first came into contact with this plant when they moved to North America. After all, smoking tobacco was a popular recreational activity among the local tribes. The practice caught on quickly with the newcomers and went onto become a fad in Europe. Modern science has proved that tobacco contains carcinogens. Handling damp plants may also cause health problems in adults. Children who are exposed to wet tobacco plants might even require hospitalization.  It’s certainly no surprise that eating tobacco can prove fatal. However, people do continue to plant various nicotiana species in their yards to attract pollinators and to serve as a trap crop. It might nonetheless be a good idea to leave such species out of the garden where small children or pets are concerned. 

Chokecherry (Prunus virginana)

These fruit bearing plants can be found in the southern portions of Canada and the northern portions of the United States. Chokecherries were often incorporated in the diet of local Native Americans. The fruits are considered safe to eat and recent studies have even shown that they are fairly high in antioxidants. However, the leaves and branches of this plant shouldn’t be consumed because they contain poisonous compounds. This particular shrub is generally more often fatal to livestock and pets than it is to human beings but it still is not without its dangers.

Larkspur (Delphinium species)

It’s no great surprise that larkspur is often used as a garden ornamental. This native North American plant is well-known for its showy flower spikes. It’s also attractive to bumblebees, butterflies, and other pollinators. The trouble is that larkspur is considered toxic to both cattle and human beings. The seeds and young plantsare the most poisonous. Ingesting them can cause severe intestinal problems and may prove fatal within a few hours. Therefore, victims should be taken to the nearest hospital as soon as possible so that they have a decent chance at survival. 

Azaleas (Azalea species)

While there are some azalea species that are native to North America, many of these shrubby hedges have been imported from Asia in order to serve as ornamental garden plants. Many places around the world are known for their azalea collections. However, members of this species can still cause great harm to human beings because the plants contain deadly toxins. Even the nectar can contaminate honey and cause it to be a health hazard as well.

Rhododendrons (Rhododendron species) 

There are several rhododendron species that are native to North America but many other varieties have been imported from elsewhere to decorate local gardens. Even so, these hardy plants are not without their downsides. Some rhododendrons contain toxins that can be harmful to both human beings and grazing animals. Eating these plants could obviously have deadly consequences. However, historical accounts have also described incidents where people were poisoned simply by eating honey made with rhododendron nectar.  

Stay safe out there!