This Dioscorea elephantipes caudex has angularly bulging surface plates formed from thin, accumulating layers like the pages of a book. The dead-looking surface bark covers a tuber of starchy succulence that is very much alive, as attested by the vine-like leafy stems growing from the top.
The deciduous vines may be replaced fairly regularly on the caudex, up to several times per annum. The dead ones take their time in disappearing from the slow-growing plant that may reach an age of several centuries, if permitted by animals like porcupines and people (Le Roux, et al, 2005; Wikipedia).