THE SYSTEMATIC WOOD ANATOMY OF THE RHAMNACEAE JUSS (RHAMNALES) .1. TRIBE ZIZIPHEAE

The wood anatomy of the tribe Zizipheae sensu Suessenguth (1953a) is described in detail. Similarities and differences between the genera are discussed in relation to the taxonomy of the tribe. Wood anatomically the Zizipheae are rather heterogeneous and not clearly separated from the other tribes of the family. The large genus Ziziphus is divisible into three distinct anatomical groups, which closely correspond with the distribution pattern of the species. Condalia, Condaliopsis and Microrhamnus are characterised by dendritic vessel distribution, a pattern that is present in three out of the five tribes of the Rhamnaceae. Due to the differences between the 'Condalia group' and the other genera with dendritic vessel pattern (tribe Rhmneae and Colletieae) it is suggested that this characteristic syndrome originated at least two times independently in the evolution of the Rhamnaceae.