The main stem or base of a Portulacaria armiana plant is thickly succulent, covered in papery bark that peels in slightly translucent strips. The olive green to pale brown stem is otherwise smooth.
The scars or short stumps where old flowering stems of earlier years had broken off are visible in the photo among the leaves (Williamson, 2010; Frandsen, 2017; iNaturalist; Wikipedia; http://pza.sanbi.org).