It may sound like an unnecessary question, but it’s not. When one stops to think about it, a rather long list of things to consider when planning a landscape could be made.
In nature, many plants have defense mechanisms to ensure survival. These mechanisms may include ways to physically deter a predator, like thorns or spines.
Others have developed chemical defenses. To assist in evaluating plant risk in a garden, the following categories of plant defense mechanisms include examples of plants that can cause physical harm, injury or in the extreme, even death.
PHYSICAL DEFENCES
Spikes & thorns:
Many plants are equipped with defensive spikes or thorns to deter threats. These spikes and thorns are often extremely sharp and can easily penetrate or tear flesh.
Examples include cacti, Spanish bayonet, roses, Citrus spp., needle palm, silver thorn, and Phoenix palms to name a few. Some, like Firethorn, have thorns that are coated with chemicals that can cause irritation and inflammation to the wound, resulting in additional tissue damage.
Cutting or sawtooth edges:
Other plants, especially grasses and palms, have sharp edges which can cause injury.
Pampas grass has a saw-like edge on the long leaf blades. Many Florida palms like Saw Palmetto have sharp saw-like edged petioles that can cut and tear the skin.
CHEMICAL DEFENCES
Irritants:
Many species of plants have chemical qualities that may provide a deterrent to being handled or eaten. Some of these, like philodendron, have a sap that causes significant skin irritation.
Others, like poison Ivy, poison oak and poison sumac, while not ornamental, are often present in residential gardens. They contain a chemical irritant in the form of an oily resin called urushiol that bonds with skin cells and causes rashes and blisters.
Blending easily into the green environment of spring, poison ivy is endemic to the region. More of an irritant than anything else, contact can result in countless hours of itching.
Breathing the smoke of burning poison ivy can also cause irritation to the lips, mouth and lungs. For this reason, it is illegal to burn poison ivy in many states.
Other chemical defenses make the plant too unpleasant to ingest. A common example is peppers which are hot to the taste, some hot enough to cause blisters to the mouth.
Having small, colorful ornamental or edible peppers growing where small children can access them is not a good idea. Many a child has had the unfortunate experience of rubbing their eyes after handling pepper fruits.
Then there are plants like the ornamental pencil cactus, a plant in the genus Euphorbia, which has sap that can cause permanent blindness if it gets into your eyes.
Toxins:
Some of the toxic plants are mild enough to cause digestive upset. For example, chewing the leaves of the Ilex vomitoria, which is in the holly family, will cause what the name suggests if ingested.
Native Americans used it to make a purgative tea. Others, like oleander, if ingested, can cause death. The smoke of burning oleander is also toxic.
Foxglove, which contains digitalis, can be lethal.
Hemlock causes death by respiratory paralysis. It was used by the Greeks in the form of a drink as a method of execution.
Tomato and potato plants are members of the deadly nightshade plant family and while the fruit and/or roots are edible, the leaves are toxic.
Eating the seeds of thecoontie (Zamia pumila), a native ornamental, can result in death to humans and dogs.
Other common plants toxic to humans include allamanda (Allamanda cathartica) of which all parts of the plant are poisonous, especially the seeds, and pokeweed (Phytolacca americana) another plant of which all parts are poisonous, especially the seeds and roots.
HALLUCINOGENS
Finally, there are plants that have the ability to alter the user’s perceived reality, the hallucinogenic plants. The sap of angel’s trumpet is hallucinogenic if it is ingested or comes in contact with the skin.
Another example is the hallucinogenic mushroom. While these plants are typically not deadly, persons under their influence using them as recreational drugs may severely injure themselves. Historically, many were used in religious rites.
Newly emerged mushrooms may appear to a small child to be a toy. While most mushrooms just taste bad, there are species which have toxic qualities. If children are present, it is best to remove the dangerous attraction and avoid potential problems.
Therefore, if you are planning a new landscape, or if you already have an established garden, it may be wise to take time to review your plant palette with the purpose identifying plants that may pose a risk to the user population.
This is especially important in gardens where young children may be present. Owners of gardens may reduce liability risk simply by anticipating and avoiding potential injuries or undesirable episodes by taking appropriate preventive steps to avoid unintended harm or injury.
There is a wealth of knowledge available on the internet to help in evaluating plant risk. This is not only for the well-being of family, friends or visitors, but for pets as well. There are sites that also offer information on plant toxicity to differing species of pets.
As mentioned above, there can be a potential for litigation as a result of an event which could have been avoided had proper plant selection choices been made. Most personal injury litigation is brought as the result of “negligence.”
Negligence is often defined as either doing something a reasonable person should not do to cause harm or not doing something a reasonable person should do to prevent harm.
Given that it is common knowledge that many frequently used plants do have potentially severe risks to people (and pets) it is not unreasonable to assume these risks should be considered in the selection of plants for your garden.
If the general public and/or young children have legitimate access and could come into contact with dangerous plants resulting in injury or worse, err on the side of caution.
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