Paul Rudy makes sounds from amplified cacti. He places contact microphones on them, and then coaxes sound from them by brushing his hands against the spines. The range seems to be anywhere from a rustling to a momentary twang to a hollow pop. And that's it. Rudy describes the results as music, but I can't make the connection myself. The sounds themselves are fascinating, but I find it difficult to hear any musical intelligence behind his arrangement of noises.
It's fair to say that Degrees of Separation "Grandchild of Tree" doesn't really get going until the quiet undulations of Rudy's backing tape becomes audible. It's a shame, as this is a piece with a rich heritage, composed in response to John Cage's 1975 work Child of Tree, also written for amplified cactus. I think Cage was exploring randomness in music by deliberately giving the performer an unfamiliar instrument, whereas Rudy has been specialising in playing the cactus for some time now. However when he tours, he does at least buy a new cactus from a local shop, so there's that.
Perhaps one of you will have more luck with this than I do?
Paul Rudy - Degrees of Separation "Grandchild of Tree"