Dangerous Landscape Plants

My last blog was about the poisonous plants that grow wild all around us. But as I was researching that I became increasingly surprised by the number of plants people willingly and commonly bring into their yards that can actually kill them or their pets. You can probably find at least one of these in gardens in your  neighborhood. Here are some examples that may surprise you as well. 

Oleander (Nerium Oleander) – 

This plant can be found all over here in Tucson. It grows well in our harsh climate and provides quick-growing privacy in many areas. It is also extremely poisonous - a fact that has always been commonly known and commonly ignored. That is until the giraffe died.  Back in 2011, a male giraffe at the Reid Park Zoo here died after being fed oleander clippings. At the time, animals were often fed clippings from the plants around the zoo. Apparently a young apprentice did not know that oleanders were poisonous and included some in their feed. After the death, the oleanders that formed a large wall around the zoo were belatedly torn down and there was a whole lot in the news about the dangers of oleanders to humans as well as animals. Unfortunately, it appears that whatever messaging that was sent out then may have been forgotten by now, as there are still oleanders everywhere. 

Castor Bean (Ricinus communis) –

This attractive plant with showy flowers is a native of Africa and was introduced to North America as an ornamental way back in the early 1800s. Sure, it’s pretty; but it’s also deadly. With the castor bean plant, it’s the seeds that hold the danger. They contain ricin, a toxin that interferes with cell function. The beans need to be ingested to be a threat, but it does not take many. According to this article, three seeds can kill a child and seven can kill an adult. Ricin has been in the news as far back as 1978, when Bulgarian journalist Georgi Markov was killed by a man who attacked him with an umbrella that had been rigged to inject him with ricin. Over the years, ricin has been sent to several US politicians, including Donald Trump in 2020 (no one was hurt in any of these instances). Oh, and Walter White used ricin to kill an associate in Breaking Bad. The relative availability of such a serious poison has led to many cases of ricin poisonings and attempted poisonings. Picking a plant for your yard that has such a lurid backstory is probably not a wise, or socially conscious, thing to do. 

Rhododendrons (Rhododendron spp) – 

My mother loved these plants and always had them in her Northern Virginia home in multiple colors, but I do not recall every being cautioned about them. According to Colorado State University, all parts of this plant are toxic and most poisonings that happen involve animals in winter months. At that time of year when other food sources are scarce, animals are attracted to the rhododendron's evergreen leaves as something to feed on. With people, poisoning has most commonly  been caused  by “Mad Honey”. This potentially fatal treat is created by bees that source their nectar from dense growths of rhododendrons. The Mad Honey term reflects the disorientation that is one symptom of rhododendron poisoning. There are also some people who actually ingest this on purpose in the belief that it has medicinal properties – they soon learn otherwise. 

Lantana (Lantana camara) – 

A native of Central and South America, lantana is now all over the place here in Southern Arizona. It tolerates drought well, so it’s been a xeriscape favorite and butterflies like it, so it’s popular in butterfly gardens. But it’s become invasive. And, yes, it’s also poisonous. All of this plant is toxic, but the greenish-black seeds seem to be the most attractive to children, livestock and pets and therein lies the problem. They may find them appealing enough to nibble on them. The “good” news is that it takes more than a nibble to experience the worst of the poison. This article says that approximately 1% of their body weight needs to be ingested before symptoms kick in. Between its toxicity and its invasive habit, this is a plant that should be shunned. If you have some in your yard that you’d like to remove, be cautious doing so as contact rashes are common. Also, never burn them – the smoke is toxic. Side Note: This plant never bothered my child; she found its little groups of flowers to be the perfect Barbie bouquet (of course, this was well before I knew they were invasive and toxic).

Hydrangeas (Hydrangea spp) –

This is another beauty that is surprisingly toxic. Their abundance of beautiful blooms and long growing season make them a garden favorite. But it contains toxins that break down and produce cyanide, so it’s a beauty with a dangerous little secret. This plant is not generally a problem for humans as the amount needed to induce a poisoning is substantial. There are some misguided humans, however, who smoke hydrangeas (apparently the effects are similar to THC). Not advisable. A lot of the poison in hydrangeas are in their gorgeous flowers and often pets like these flowers as much as their owners do. If your pets are chewers, find a way to keep them away, with their small bodies it won’t take a lot to poison them. According to this article, dried hydrangeas (the kind found in wreaths and other floral arrangements) are just as poisonous as the living ones. So, if you have these lying around and your indoor cat nibbles on things, you may want to reconsider your décor. 

There are many other plants out there that have poisonous tendencies. I encourage you to look beyond a plant's beauty or how easy it is to grow when deciding what to put in your yard (especially if you have children or pets). A little research can go a long way to avoid nasty toxic surprises. While you’re at it, make sure you are not planting anything that is invasive. And if the plant in question is toxic and invasive, it should be a hard “No”, no matter what. Also remember that just because a plant comes from a local nursery or big box store does not mean it should go in the ground in your neighborhood.

Take Care.

Submitted by Pam