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Within the Aizoaceae, the genus <i>Delosperma</i> exhibits a vast diversification colonizing various ecological niches in South-Africa and showing evolutionary adaptations to dry habitats that might include rapid self-sealing. Leaves of <i>Delosperma</i> react to external damage by the bending or contraction of the entire leaf until wound edges are brought into contact. A study of leaf morphology and anatomy, biomechanics of entire leaves and individual tissues and self-sealing kinematics after a ring incision under low and high relative humidity (RH) was carried out comparing the closely related species <i>Delosperma cooperi</i> and <i>Delosperma ecklonis</i>, which are indigenous to semi-arid highlands and regions with an oceanic climate, respectively. For both species, the absolute contractions of the examined leaf segments (“apex”, “incision”, “base”) were more pronounced at low RH levels. Independent of the given RH level, the absolute contractions within the incision region of <i>D. cooperi</i> were significantly higher than in all other segments of this species and of <i>D. ecklonis</i>. The more pronounced contraction of <i>D. cooperi</i> leaves was linked mainly to the elastic properties of the central vascular strand, which is approximately twice as flexible as that of <i>D. ecklonis</i> leaves.