Tag Archives: Oleander

Two of my favourite families, entwined

Late on Wednesday night, Karin and I returned, tired but happy, from an eight-day trip to southern Spain, where we celebrated the marriage of our son Oli to his partner Kate. Our base for the trip was the small town of Benahavis, a former Moorish enclave in the mountains above the Costa del Sol.

As well as spending time with Oli and Kate and the other guests, Karin and I took the opportunity to explore some of the many trails that meander through this wonderful landscape. One of these crosses, then follows, the spectacular canyon of the Guadalmina river, the trail shaded by over-arching trees that provided relief from the hot sun.

Many of these small trees, I was delighted to see, were oleanders (Nerium oleander) growing in what is (arguably) their natural habitat. It’s been so widely planted for thousands of years that the true origin of this species is unclear, but it’s almost certainly native to the Mediterranean basin.

Twining through one of these oleanders was a plant with heart-shaped leaves and dangling fruit that I instantly recognised – the Andalusian pipe vine (Aristolochia baetica). As a climber, this plant needs the support of trees and shrubs to enable it to reach the light. The supporting species is not harmed and likely benefits from the nutrients in the dead leaves and flowers that fall beneath it.

The juxtaposition of these two species was so perfectly symbolic of our reason for being in Spain that I had to take the photo that you see above. Why, you may ask? Well the oleander is a member of my all-time favourite plant family, Apocynaceae, that I’ve worked on for more than 30 years. The pipe vine belongs to the Aristolochiaceae, another fascinating family that’s also in my top five favourites.

That’s the thing with families, sometimes they come together and entwine in ways that just feel and look…right. Huge congratulations to Oli and Kate, and our very best wishes for a long and happy future together!

Is it safe to use oleander to treat COVID-19 symptoms?

No, it’s not safe. It’s a really, really dumb idea. Oleander is VERY poisonous and you could die. Do not do it.

OK, that was the short version; here’s the longer version. Oleander (Nerium oleander) is a plant belonging to the plant family that’s been the focus of much of my research for the past 30 years: Apocynaceae. The plant is widely grown in warm temperate and subtropical areas as an ornamental shrub or small tree and there are cultivars with flowers in a diverse palette of colours. In the Mediterranean, where it’s native, it’s a pollination generalist and pollinated by large bees, hawkmoths, and small flies. However, visitation to flowers is infrequent because, as Javier Herrera showed in this study, the flowers produce no nectar. It’s a rare example of a species of Apocynaceae with rewardless flowers in a family with very diverse pollination systems, as we showed in our study last year.

Although it’s very beautiful, oleander is also extremely poisonous. Many members of the family Apocynaceae are toxic: they are crammed full of alkaloids, cardiac glycosides, and other nasty chemicals that defend the plant against all but the most specialised of herbivorous insects, such as monarch butterflies (Danaus plexippus). But even in a family renowned for its toxicity, oleander stands out as being especially lethal.

Recently, a chemical derived from oleander called oleandrin has been touted as a health supplement to treat patients with the COVID-19 coronavirus. However there is no evidence that it is effective as a treatment but a LOT of evidence that it is highly toxic to both animals and humans. The fact that’s being touted as a COVID19 treatment by President Trump and some of his pharmaceutical industry donors should ring alarm bells for anyone with any common sense. And just because it’s a “natural” product does not in any way make it safe. DO NOT EAT OLEANDER!