Echeveria Leaf Morpho-Anatomical Analysis and Its Implications for Environmental Stress Conditions

Abstract

Echeveria, classified in the Crassulaceae family, possesses unique adaptive strategies with xeromorphic features to withstand semi-arid environments. The diversity and ecological adaptation of succulent plants offer valuable insights into addressing climate change challenges. In particular, the epidermis, hypodermis, vascular bundles arrangement, and stomata characteristics are commonly used to investigate light, humidity, temperature, and water availability adaptations. While leaf anatomical analysis is a common approach, limited studies have been conducted on Echeveria, especially among cultivars. To understand how succulents cope with environmental stress, leaf morpho-anatomical features were analyzed using the free-hand sectioning method with methanol fixation of fifteen Echeveria cultivars. The finding revealed a robust correlation between epidermis and hypodermis size (r = 0.362–0.729), and a positive association between leaf thickness and the epidermis (r = 0.362–0.536), suggesting implications for water storage. Most cultivars displayed a 3D vascular arrangement, with minor vascular bundles surrounding the main vascular bundle at the center, along with small stomata size, and low stomata frequency in the adaxial surface. Moreover, these cultivars grown under controlled conditions maintain their xeromorphic characteristics with the presence of epicuticular wax and thick and fully expanded small leaves. Likewise, the features of cultivars ultimately suggest that these succulents are tolerant to high temperatures and limited water supply. This study provides a fundamental understanding of Echeveria plants’ leaf anatomy and the correlation of their leaf structures toward environmental stress. Likewise, the methods and results of this study will serve as a benchmark for other research in related species.