Cambial Variations of Three Lianoid Genera, Akebia, Stauntonia, and Sabia (Lardizabalaceae and Sabiaceae), in Taiwan

Descriptions of the cambial variants of the lianoids in two families, Lardizabalaceae and Sabiaceae, were lacking in Taiwan. This study aimed to diagnose the stem characteristics of seven lianoid species from these two families to update existing knowledge. Specifically, the transverse sections of fresh stems were diagnosed to generate a key. The results showed that all seven species develop one of ten cambial variant types, viz. axial vascular elements in segments. Of these species, Sabia swinhoei Hemsley, Stauntonia obovata Hemsley, and S. obovatifoliola Hayata formed secondary rays. The thick and successive periderm was apparent in Stauntonia obovata and S. obovatifoliola at older stem. The sclerenchyma ring was continuous or discontinuous in two genera (Akebia and Stauntonia), but was absent in Sabia. Four diagnostic features could be used to distinguish Lardizabalaceae and Sabiaceae; namely, the periderm, cortical sclerenchyma, vessel arrangement, and cortex ducts. The cambial variations documented for these seven lianoid species in Taiwan update existing information, facilitating comparisons between Lardizabalaceae and Sabiaceae.