These cactus-looking trees are called Uforia. I'm not sure of the spelling. They are fascinating, to say the least.
This is James, our "guide" for the day. - he was great! It actually seems to me like the word "guard" should be used, though. It's strongly recommended that hikers hire one of these guys for a hike at Ngong Hills (at $14 for the day, with the money going to the Kenya Wildlife Service). "Thugs" (thieves, rapists) are common, as are buffalo! We saw the footprints of a leopard and could smell the remains of a "kill" that a leopard had consumed. James told us incredible stories of 6 "jumbos" (elephants) that had strolled through the hills just two weeks prior. It was an exciting adventure, to say the least! I've now gone there four times and have loved it each and every time.