The flat, pinkish upper surface of the sturdy Arctopus echinatus leaf petiole in picture is smooth without spines along its sharply angled upper surface.
The proper leaf margin next to it hardly has teeth at the bases of the thin, thread-like protuberances spaced along it. They hardly deserve to be called spines.
The two unlike margins are juxtaposed because the leaf rosette positioned flat on the ground has longer, stalked, older leaves below the shorter, young ones. That is the situation when there is not enough space for them to lie next to each other as here (Manning, 2007; iNaturalist).