These chubby stems of Piaranthus geminatus, green from growing in ample shade after the benefit of rain, have separate segments caused by spaced constrictions. The stems vary in thickness and shape.
Although well-rounded, the stems are not simply cylindrical: stem tubercles, tiny and white-tipped, are spaced along the four or five stem ridges. Slight indents are visible in a few places in the photo, indicating the divides halfway between the stem ridges.
These indentations are more prominent in dry seasons: the ample plant succulence currently enjoyed makes them disappear like wrinkles from a fat face (White and Sloane, 1937; Vlok and Schutte-Vlok, 2010).