SYSTEMATIC ANATOMY OF THE LEAF EPIDERMIS IN THE MAGNOLIACEAE AND SOME RELATED FAMILIES

Summary Stomatal and other epidermal features suggest a close relationship among the Magnoliaceae, Eupomatiaceae, Degeneriaceae, and Himantandraceae, a somewhat more distant relationship of the Winteraceae to these families, and only a much more distant relationship of the Illiciaceae and Trochodendraceae to this group. Epidermal characteristics of the various genera and species of the Magnoliaceae are highly compatible with the taxonomic scheme of Dandy, and in some respects give strong support to it. The generic separation of Manglietia from Magnolia is particularly supported by my studies. Within the Winteraceae, epidermal features of several species of Belliolum correlate well with the system of A. C. Smith for this genus. The species Bubbia perrieri is anomalous in Bubbia on epidermal features, though clearly a member of the Winteraceae; its taxonomic position merits reconsideration. Many members of the Magnoliales have thickened lamellae (distinct from the outer stomatal ledge) on the outer walls of the guard cells, similar (except in not being lignified) to such lamellae in the modern Cycadales. The presence of these lamellae is considered to be a primitive feature among the angiosperms. Thick‐walled epidermal cells with pores in the outer wall are found in many of the Magnoliales, and this feature is also considered to be primitive within the angiosperms. It is noteworthy that the Cycadales also have thick‐walled cells, and that in Cycas and some other genera these cells have pores in the outer walls. The vast majority of the Magnoliales have paracytic stomates, and this is considered to be the primitive type within the angiosperms.