this has been my experience as well. have generally assumed if a yucca blooms late (october/november) it was gloriosa or had gloriosa genes. i have what i suspect is a gloriosa hybrid with possible aliofolia (sp?) genes in it. had a great bloom that was finally caught by frost in november. leaves resemble aliofolia somewhat.this clone does bloom in late spring or early summer as well. will remember to leave stems intact next summer bloom to see if any pods develop. hesitated to comment on photo since i do see a lot of similar yuccas in my local area, but was not sure of the parentage.