The following new isoquinoline alkaloids have been isolated from T. fendleri: the bisbenzylisoquinoline thalidezine (IIIb), and the aporphines thaliporphine (XI) and preocoteine (XIV). Thaliporphine has been assigned a structure previously given to glaucentrine. The plant genus Thalictrum has a pronounced tendency to produce isoquinoline alkaloids possessing the trioxygenated moiety XIX. © 1967.