Seed anatomy and development in cycads and Ginkgo, keys for understanding the evolution of seeds

•Cycas and Ginkgo are one of the first extant lineages in which seeds evolved.•Literature review of the morphology and anatomy of seeds in cycas and Ginkgo.•We provide updated photographs of the anatomy and morphology.•Major structural differences between Ginkgo and cycas seeds like the vascular patterns.•Likely, the evolution of cycas seeds is by sterilization and fusion of sporangia.