Succulent plants are drought-resistant plants that store water in specialized tissues, which can be remobilized during drought. Several co-adaptive traits accompany this water-storage capacity to constitute the succulent syndrome, which has evolved convergently in numerous plant lineages. Collapsible cell walls in succulent tissues are able to fold in a regular fashion as water is lost, thus preventing irreversible damage and permitting reversible volume changes. Despite the alleged importance of cell wall traits for the succulent syndrome, their ecophysiological significance has long been overlooked. On another note, many succulents occur in (semi-)arid habitats with periodically high atmospheric humidity, in the form of fog and dew. The leaf-succulent genus Crassula is a characteristic element of the southern African flora, with many species occurring on the foginfluenced western side. Foliar water uptake through hydathodes has long been suspected in Crassula species as an adaptation to aridity, yet solid empirical proof and visual evidence are still lacking. This PhD thesis aimed to address these two major knowledge gaps. A preliminary literature review on the current knowledge of cell walls in succulent plants revealed that much more research is needed to fully understand their ecophysiological relevance, with ramifications for tissue biomechanics, water relations and photosynthesis. Research efforts should focus on the cell wall dynamics of succulent tissues, which may be the underlying mechanism for cell wall folding. Through biomechanical modelling and glycomic profiling using CoMPP, the results of this work revealed several key differences between succulent and non-succulent plants. Elastic adjustment seems to be uniquely beneficial to succulents for avoiding turgor loss, while glycomic differences, particularly regarding pectic polysaccharides, point to the existence of a ‘succulent glycome’. Furthermore, glycomic profiling using CoMPP also shows differences within a phenotypically diverse group of succulent plants. Using Crassula as a model, this work reinforces the link between glycomics and growth form diversity in succulent plants, which is in turn related to drought tolerance. Therefore, the results presented here reaffirm the relevance of cell walls and glycomics to the succulent syndrome. A deeper insight into the relationship between cell walls and the succulent function would be particularly useful given the potential of succulents as natural capital to mitigate the effects of climate change. In this study, the use of an apoplastic fluorescent tracer confirmed that hydathode-mediated foliar water uptake does indeed occur in Crassula and is probably widespread across the genus. Foliar water uptake could be induced even in Crassula species that do not occur in (semi-)arid habitats influenced by fog, so that the benefits of water absorption may extend to the whole genus, even to those species occurring in more humid environments. Moreover, a link between surface wettability and water uptake ability could not be found, as water absorption was observed even in species with seemingly hydrophobic leaf surfaces. These findings have major implications for our understanding of the evolutionary history of Crassula and the ecophysiological relevance of foliar water uptake to this genus and other sympatrically occurring plants.