Tim EntwisleA plant with a twist, nearly missed

It’s so easy to miss a quirky flower or fruit in Melbourne’s Royal Botanic Gardens. There is just too much going on. You have to always be on the look out for a fleck of colour here or a odd bauble way up there. Back in early February I discovered this Corkscrew Tree on twitter. It was flowering beside a major path near the Canna Bed, but it wasn’t until I tracked back from a tweet to MelbourneDaily that I realised it was in my own (work) backyard.

Corkscrew Tree Strophanthus flower closeup

Corkscrew Tree Strophanthus flower closeup

Nick V. posts occasional, and always well illustrated, posts on MelbourneDaily. His pictures are always great and he does his research. These are my pictures, with only a little more research! Nick headed his story ‘Pretty Deadly’, which is a sure way to attract attention. Like lots of plants in the Apocynaceae (think Oleander) the Corkscrew Tree is poisonous in anything but extremely small quantities, and then sometimes medicinal. The PlantzAfrica website lists among its common names Poison Rope, Common Poison Rope and Forest Poison Rope.

Corkscrew Tree Strophanthus flower

Corkscrew Tree Strophanthus flower

I get the poison bit and thought perhaps the length of the unruly shoot heading out of this generally pruned plant (to the top right) might be an indication that its flexible branches are used for rope, albeit of a poisonous kind. In its natural habitat, in the forests of south-eastern Africa, I gather it is a scrambling climber.

Corkscrew tree Strophanthus form

Corkscrew tree Strophanthus form

My rope theory is supported by a Flowering Plants of Africa synopsis of the species but the genus name Strophanthus means ‘twisted-rope flower’, because the petals have a jaunty twist, so it may be that the term Rope in the common name references this too. In Australia we call it the Corkscrew Tree, again a reference to the flower. Or sometimes simply Corkscrew Flower.

Corkscrew tree Strophanthus flowers

Corkscrew tree Strophanthus flowers

The genus Strophanthus is widespread in Africa, with a handful of the 38 species in Asia. The various species pop up in herbals and healing websites, usually with strong warnings about the toxicity of the leaves and seeds.

Strophanthin, present in the seed of most species, is a little like digitalis in its action. It can stimulate muscles, like the heart, and it can kill when painted onto arrow tips (a single seed crushed and glued to the end of the arrowhead is enough to increase contractions then seize the prey’s heart). Apparently, antitoxins from some species can be used to treat snake bites in the absence of specific anti-venom. Here in Australia though we have good access to anti-venom and it isn’t a recommended method.

Corkscrew tree Strophanthus flowers and fruit

Corkscrew tree Strophanthus flowers and fruit

I was happy just to photograph and observe our species. The blood or red-paint splotch must surely attract the pollinating butterflies into the sexy middle of the flower. The white threads are appendages on the petals rather than the males parts of the flower (the anthers), which are nestled deep inside the flower with the female bits. (If you do tease a flower open you’ll notice the real anthers are topped by lovely soft hair, looking very un-anther like.)

Once I’d got past the twisted, blushing flowers I noticed these large, pencil-shaped fruits. When they dry out, feathery seeds are released, carried away by the wind. Strophanthus speciosus was once separated out into its own (single species) genus called Christya because the tuft of hairs at the top of the seed is hardly stalked.

Corkscrew tree Strophanthus fruit

Corkscrew tree Strophanthus fruit

So just another plant, and another story. But I almost missed it!

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Tim Entwisle

About Tim Entwisle

Dr Tim Entwisle is a scientist and scientific communicator with a broad interest in plants, science and gardens, and Director & Chief Executive of Royal Botanic Gardens Victoria. Previously he was Director of Conservation, Living Collections & Estates at Royal Botanic Gardens Kew and prior to that, Director of Sydney’s Royal Botanic Gardens for eight years. Read Tim's full blog at Talking Plants

5 thoughts on “A plant with a twist, nearly missed

  1. Bernard Chapman on said:

    Thanks for sharing, Tim! As a horticulturist I am always interested in finding out about a plant I have not come across before. The actual plant doesn’t look that attractive (rangey?), but the flowers are spectacular. Is it available in the nursery industry? Oleanders are such useful plants in tough spots, perhaps this could be an alternative?

  2. Tim on said:

    Hi Bernard,

    Your assessment is about right. Not that attractive as specimen, even when in flower. You have to get up close and look carefully. So good for the botanic garden but not so much home garden. I haven’t seen it in the trade, possibly for that reason.
    Tim

  3. Lovely piece Tim. Will have to go past the canna bed and take a look. I think plants such as this one are one of the great strengths of the MBG. There is ALWAYS something to find out!

  4. tentwisle on said:

    Thanks Anne, agree entirely. I continue to (and will continue to) discover new plants as they flower or fruit, or simply slip into my view one day due the light or my disposition!

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