"strange offshoot of traditional folk music that included Wild Man Fischer, Country Joe and the Fish, Captain Beefheart among others"
This doesn't make any sense. I have stuff by all of these people and they certainly don't fit into any "weird offshpot of traditional folk" genre. The good captain was fairly weird, WMF was also pretty weird. Country Joe & The Fish were a left wing psychedelic acid rock band. Joe himself did do a lot of folk stuff - but not weird, or belonging to the same camp as WMF or that of Don Van Vliet. The Holy Modal Rounders remebered mainly for their contribution to Easy Rider soundtrack.