A FORMAL CLASSIFICATION OF THE CYCADS

The classification of the extant cycads proposed by Dennis Stevenson in 1990 (Memoirs of the New York Botanical Garden 57:8-55) has been formalised by Dennis in a publication dedicated to the memory of Sergio Sabato (Brittonia 44(2), in press). The classification places the 11 genera and 3 families in a hierarchical structure based on cladistic analyses of morphological, anatomical, karyological, physiological and phytochemical data, and is summarised by the following diagram:

Order: Cycadales

    Suborder: Cycadineae

        Family: Cycadaceae

                        Genus: Cycas [Type: C. circinalis L.]

    Suborder: Zamiineae

        Family: Stangeriaceae

            Subfamily: Stangerioideae

                        Genus: Stangeria [Type: S. eriopus (Kunze) Baillon]

            Subfamily: Bowenioideae

                        Genus: Bowenia [Type: B. spectabilis Hook. ex Hook. f.]

        Family: Zamiaceae

            Subfamily: Encephalartoideae

                Tribe: Diooeae

                        Genus: Dioon [Type: D. edule Lindley]

                Tribe: Encephalarteae

                    Subtribe: Encephalartinae

                        Genus: Encephalartos [Lectotype: E. friderici-guilielmi Lehmann]

                    Subtribe: Macrozamiinae

                        Genus: Macrozamia [Lectotype: M. riedlei(Fishcer ex Gaudichaud) C.A. Gardner]
                        Genus: Lepidozamia [Type: L. peroffskyana Regel]

            Subfamily: Zamioideae

                Tribe: Ceratozamieae

                        Genus: Ceratozamia [Type: C. mexicana Brongn.]

                Tribe: Zamieae

                    Subtribe: Microcycadinae

                        Genus: Microcycas [Type: M. calocoma (Miquel) A. DC.]

                    Subtribe: Zamiinae

                        Genus: Zamia [Type: Z. pumila. L.]
                        Genus: Chigua [Type: C. restrepoi E. Stevenson]

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