ON SOME ASPECTS OF SYSTEMATICS AND EVOLUTION OF THE ENGELHARDIOIDEAE (JUGLANDACEAE) BY WOOD ANATOMY

Abstract. Some aspects of systematics by wood anatomy as well as wood anatomy specialization of the subfamily Engelhardioideae (Juglandaceae) are discussed. The age variation of wood anatomy over the radius of stem has been examined in the Oligocene Engelhardioxylon mameticum from Kamchatka (Russian Far East); the formation of mature wood takes in this species 9-11(15) years. The ontogenetic variability of wood anatomy was examined in the subfamily Engelhardioideae for the first time. A comparative analysis of wood anatomy specialization within the fossil genus Engelhardioxylon has been done. The development of wood anatomy characters in E. mameticum is an example of heterobatmy in the genus. The data on wood anatomy specialization within the Juglandaceae members were summarized. The Engelhardioideae is, probably, the most primitive subfamily, while the Platycaryoideae is the most advanced one. Wood anatomical characters of Engelhardioxylon mameticum correlated with habitat conditions have been implicated for palaeoclimate reconstruction. During the Oligocene this species vegetated in Kamchatka under condition of well-pronounced seasonality with relatively mild warm temperate climate throughout the year, and