It was not purposely planted amongst the roses, citrus and gerberas and I've let it wander around which turned out well, as it seemed to protect the ground, and the plants which it climbed over from this heat. It gets lightly watered twice a week with no wilting to date.
Apart from it being a Snake Bean! Pods in pairs and very Snake-bean-like foliage ... now it looks a bit like it might have crossed with a Borlotti Bean - they have that mottled purple look. Not sure if Borlotti has a climbing cousin though, the only ones I have grown were dwarfs.
There's a Purple Snake Bean and a purple-tipped one too. Who knows what mischief either might have got up to.
A lot of beans are self-fertile, some never open their flowers yet produce viable seeds. There's some weird chromosome variations in plants where they can have more than 1 pair of chromosomes and yet are perfectly formed and with viable progeny. Genetic events occur in plants which do not occur in animals.
So I wonder how a spontaneous cross could occur. Ants ... well there's lots of ants just now, more than usual on plants and paths. The Dragon Fruit are populated by large ants which run all over the stems, flowers and fruits.
Perhaps it's not so impossible for cross-pollination to occur with ants being the bearers of 'foreign' pollen.
I had this growing a couple of years back - no doubt the info is in a blog somewhere. Could you have acquired some seed during a visit?
Found them in last summers blog:
22.12.15 Some of the snake bean crop. The red come from Pat Pierce's seed. The speckled comes from lord knows where. A throwback perhaps.
They're the ones, thanks, and thank you Lissa!
The bean pod would have sat on the window sill on the corner of the house for many months. The plant grew less than a metre from where the seed pod was. Order eventually came out of the disorder of my storage method.
No worries :)
Pat might be pleased that her beans are continuing to spread themselves around. She hasn't been on the site for some time.