Things don't always go as planned in the world of adventure travel. When fog socked in Walvis Bay, we made an unscheduled stop in Arandis, Namibia. We predict that no one reading this blog has ever been there (or, for that matter, heard of it). Arandis is out in the middle of mining country -- including one of the world's largest uranium mines.
You have to make the most of these opportunities, so we all started wandering around the nearby landscape. We added several new birds to our life lists (the Brubru and the surprisingly-named Fiscal Shrike). And we also found the cactus-looking plant in the picture.
As our guide David explained, it's not a cactus. It's a euphorb. In Africa, some species of euphorb have evolved to fill the niche that cactus fill in the new world. An excellent example of convergent evolution in which entirely different species have evolved very similar ways to live.
Another example: In the new world, we have hummingbirds with long curved bills that are perfectly adapted to drink nectar from deep flowers. In Africa, they have sunbirds and sugarbirds with similar bills who play a similar role.