h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

The small spiny or thorny looking plant in the photo to the right of the brachystelma, is that one a cactus or a euphorbius?

I'd expect probably the latter since its an African plant.

It is though stikingly similar in appearance to a cactus native to central America.

Hello ITIWBS! That's actually neither a cactus nor an Euphorbia, it's a carrion flower (stapeliad). Indeed it's the Huernia quinta mentioned in the text. Stapeliads are fascinating succulents, of which a vast diversity exist in South Africa!

I'll do some homework on the stapeliads.

Yeah, do yourself a favour! Just put 'stapeliads' into Google images!

My mom used to keep the stapelia giganteum.

Though I never noticed a problem with odor from it, it was worthy of the name, 'corpse flower' since it produced a pheromonal fly attractant and appeared to be fly pollinated.

Also, as I found dissecting one of its flowers once, its nectary serves as a nursery for insect larvae, something which seemed not to harm the plant.

I'm still trying to find references on the central American epiphytic cactus I remarked on.

Rhipsalis baccifera is somewhat similar with respect to stem but very different with reference to fruit and flower, probably a rhipsalis pilocarpa, with red flowers with a white midrib in the petals and green and spiny fruits.

Besides doing well as an epiphyte in rainforest conditions, it also does well in the ground in drier climates.

Prodigies of convergent evolution rarely match so closely.

"rhipsalis philocarpa"