Encephalartos arenarius uneven growth rate

Growth and rest periods in the life of an Encephalartos arenarius plant are displayed on the upper stem in picture, like exaggerated brow ridges on sloping Neanderthal foreheads. It is not known whether the growth cycle causing the unevenness corresponds to annual seasons or longer cycles.

Upper stem greenness is present on the triangular, pointed bracts, lost from lower, old stem parts as they darken. The bracts disappear in time, leaving only the swollen, truncated leaf base patches (Hugo, 2014; Coates Palgrave, 2002; Leistner, (Ed.), 2000; iNaturalist).