Embryological studies in Sanango racemosum (Loganiaceae s.l.)

An embryological study was undertaken in the Amazonian genus Sanango in an attempt to help clarify the relationship of the genus. Detailed description of microsporangium, microsporogenesis, microspore, ovule, megasporogenesis, embryo sac and development of the endosperm are presented. The results confirm that Sanango is undoubtedly related to the Scrophulariales but it remains to be determined what the most satisfactory assignment of the genus should be. On the basis of early endosperm development, Sanango appears as closely related to the Gesneriaceae as well to the Scrophulariaceae. Further studies of embryonic stages and seed coat development would be helpful in clarifying this relationship. The other embryological features studied here seem not to be of taxonomic importance. A closer relationship with the Loganiaceae (Gentianales) is improbable.