New Acmadenia heterophylla leaves reach mature length by the time they are about sixth to eighth in succession from the tip. The youngest leaves are yellow-green, darkening soon lower down.
What lies ahead for them is separation, i.e. spreading due to stem elongation and then the eventual dropping off, leaving older stems bare. Leaves are team players, serving the greater good of the plant, although it limits their own longevity.
The lateral blade halves fold in and bulge slightly beside the inconspicuous midrib of the leaf (Bond and Goldblatt, 1984; iNaturalist; http://redlist.sanbi.org).