Tim, I'd take you up on the pollen but I have never successfully pollinated a yucca. Am with you 100% on the origins of recurvifolia and gloriosa. Recurvifolia being aloifolia x flacida and gloriosa being alifolia filimentosa concava. I know that concava is now the variety used to define the species filimentosa but there is a lot of variation on concava as we know. The New Jersey and Delaware ones are not very similar to ours here along the coast in N.C. The latter having very erect boat shaped leaves.