Deadly roadside beauty, in season

Oleander is a well known but hardly loved garden plant in Australia. You see it out the front of rental properties and blocks of cream-brick units, or more recently in dwarf form on motorway verges and median strips. Key attributes are its gaudy pink flowers, tolerance of the most extreme of growing conditions, and ability to kill pets and small children.

Stuck in my head are stories of a child dying after digesting a single leaf and a group of soldiers (with Alexander the Great, or Napoleon - take your pick) who roasted a pig on a Oleander spit and suffered horrid deaths. The reality seems to be that 5 to 15 leaves can cause a fatal poisoning, but there are varying reports of tolerance and toxicity among the young and old.

All parts of Nerium oleander are toxic, due to something called a cardiac glycoside. These heart-stopping chemicals are most concentrated in the seeds and roots, followed by the fruits and leaves. Red-flowering forms have more cardiac glycosides than white-flowering forms, and there is more of it at flowering time.

First-century Roman naturalist, Pliny the Elder mentions the flowers and the poisonous qualities. His countrymen also knew it as a cure for hangovers - although in the wrong quantity it would seem to be a permanent cure. Used medicinally since at least Roman times, these cardiac glycosides have deleterious side effects and of course in the wrong dose will kill you.

So you have to be careful with this plant. But then there are many toxic plants out there so unless you are growing a known vegetable or other food plant, don't nibble any leaves.

The classic flower colour is pink but they come in all kinds of red and white tones. In full blush, they can look attractive. Out of flower, it's a personal thing I guess. Better perhaps than concrete.

Like any plant (or thing) they can be evocative in the landscape. I have fond memories of whizzing past them in my hire car when touring through southern Spain back in 2008, through countryside like this between Cordoba and Granada.

Apart from its landscape attributes and deadly contents, is there anything else you should know about Oleanders? Well, it is even more common in Spain than Australia, which is why it's in my special series of pre-Spain-tour posts. Not only is it widely planted on roadsides and in gardens, but it seems to be native to the Iberian Peninsula and the Mediterranean region more generally, as well as further south into northern Africa, and west into Asia.

There are plenty of cultivars, accounting for the various flower colours and forms, as well as shrub heights. The flower I've posted at the top is a double-flowered form, probably Nerium oleander 'Splendens'. On mass, as I said, they can impress.

I personally haven't taken much notice of the seedpods but the beautiful photographs by Anne Laurent at Print Magazine reveal another side to them, and their fluffy seeds.

As to the vegetative plant, perhaps the most interesting thing is the way they are joined to the stem, in groups of three with the stalk of each expanding at the base to join with the other two. Other than that, watch out for the milky sap when pruning and remember to wash your hands.

Images: From southern Spain in 2008, except for the close ups of flowers and leaves, which are from the Melbourne Gardens in February 2017.

And do check out the elegant and informative page on the HelloGardening site, all about how to grow and care for your Oleander.