Toxic Plants In Home Gardens

Even toxic plants have their attributes.

Oleander that inhabits freeway medians is poisonous enough to be hazardous. Two tons of Buick cruising at sixty-five miles per hour past such oleander has more potential to be hazardous. The risk associated with toxic plants within freeway medians is as limited as their accessibility. Remarkably durable and resilient oleander is therefore quite practical.

Realistically, established oleander is quite practical for many landscapes. (Oleander leaf scorch limits the practicality of new installation though.) It is not the sort of vegetation that is appealing for consumption. Caustic sap should deter anyone who tries. It is poisonous primarily to curious young children or chewing dogs. It is generally safe in their absence.

Foxglove, angel’s trumpet, castor bean, nightshade and poison hemlock are significantly more hazardous because they are easier to consume. The seeds of castor bean and the fruits of nightshade actually seem to be edible. Poison hemlock sometimes mingles with foraged greens. Many diverse toxic plants exhibit hazardously appealing characteristics.

Some toxic plants are appealing enough to come indoors, where cats who never venture outdoors might take an interest in them. Dumb cane (Dieffenbachia) is a popular but very toxic houseplant. Mistletoe, although a parasitic and undesirable weed, is popular as cut foliage at Christmas. Its berries are very toxic. Poinsettia exudes caustic sap if disturbed.

Some toxic plants are toxic only because they are allergens. They affect only those who are allergic to them. Most people are allergic to poison oak. Fewer are allergic to related plants, such as African sumac. Some people are more or less allergic to a few species of Grevillea or Primula. Reaction to such species can be comparable to that of poison oak.

Too many toxic plants inhabit home gardens to list. Some are familiar fruit and vegetable plants, such as elderberry and potato. Some should be removed for the safety of children or pets. Selection of new plants can simply and conveniently omit any concerningly toxic plants. Generally though, with responsible interaction, most toxic plants are not too risky.

Toxic Plants Are Diversely Enigmatic

Smoketree is related to poison oak.

There is no single reason for toxic plants to be as potentially dangerous as some of them are. They are toxic by various means, and to various degrees. Some actually seem to be incidentally toxic. Many are intentionally and justifiably toxic. A few live in home gardens and landscapes. Of these, a few surprisingly produce safely edible fruits and vegetables! 

Immobility is a major disadvantage for plants. Those that begin to grow where resources are inadequate are unable to relocate to more accommodating situations. Those that live within ecosystems that periodically burn must either regenerate efficiently after fire, or be resilient to fire. Flowers of all plants must rely on other organisms or wind for pollination.

Since plants are immobile, they can not evade other organisms that eat them. Therefore, some do what they can to be unappetizing for the organisms that are most threatening to them. Some use thorns or similar protective devices. Unpalatable tomentum (fuzz) works for others. Many use unappealing flavor. Some are unappetizing because they are toxic.

Toxic plants are generally not toxic to a broad range or organisms. Insects eat plants that are very toxic to mammals. Onions, although commonly consumed by humans, are toxic to canines. Fortunately, most organisms instinctively know what plants are toxic to them, and avoid eating them. Unfortunately, humans and canines are occasionally exceptions.

Because young children put random items into their mouths, and puppies chew anything that they can get their teeth around, they should not have access to toxic plants. Morning glory, foxglove, yew, oleander and castor bean are some of the more poisonous of plants that are common in home gardens. Dieffenbachia is a potentially dangerous houseplant. 

African sumac and smoketree are related to poison oak. Although not so poisonous, they are incidentally toxic allergens to those who are sensitive to them. (Incidental toxins may not be intentionally deterrent to consumptive organisms.) Hellebores are both poisonous and very allergenic. Poinsettias and their relatives are toxic because of their caustic sap.