I tried an extraction on Desmanthus illinoensis a few years back. It was made using the whole roots (not just root bark), obtained through a vendor. Not sure on how or when they were harvested. They were very tough roots, you'd better have a good coffee grinder because I bought a shitty one and busted it within minutes!
What I did manage to grind up, was then triple boiled for three hours in water with a little vinegar, then reduced to a small volume of liquid. It was basified with sodium carbonate, then washed with diethyl ether. This was before STB extractions were common, and so I was just making up the tek as I went along. When the ether was evaporated, a small pile of greyish powder was left.
Vaporization was attempted, it had a generic tryptamine-like smell and produced a very mild alteration of consciousness. Nowhere near a breakthrough. Not sure if there was a failure in the extraction tek, or if the root bark contained less active tryptamines. I have heard that some strains of this plant are high in DMT, while others contain little DMT.