Histology of Indian Aquatic Nechamandra alternifolia (Hydrocharitaceae)

Nechamandra alternifolia, the only species in the monotypic genus Nechamandra, has often been overlooked in scientific research, despite its unique evolutionary status and significant ecological potential. This study presents an in-depth histological analysis of N. alternifolia, revealing a range of primitive and specialized anatomical features that distinguish it from other aquatic plants. Unlike more evolved species, N. alternifolia has a highly thalloid structure, lacking a cuticle and stomata, and is devoid of aerenchyma, suggesting a more basal adaptation to its aquatic habitat. The vascular system of N. alternifolia is remarkably primitive, consisting solely of phloem with no xylem, and its vascular bundles are simple and non-lignified. The plant also exhibits primitive spines and unique pink pigmented cells that are thought to enhance the absorption of blue wavelengths, which is vital for photosynthesis in open water conditions. A distinctive feature of N. alternifolia is the arrangement of its oval chloroplasts, which are strategically positioned near the cell wall in a lamina configuration. This arrangement, coupled with active cyclosis, is likely an adaptation to optimize photosynthesis by maximizing light capture and efficiency within its specific cellular architecture. These histological characteristics not only highlight the evolutionary significance of N. alternifolia but also its adaptability to particular ecological niches. Despite its seemingly primitive anatomy, the species shows a high potential for invasive behavior, particularly in non-native environments where its colonization could disrupt local ecosystems. Given its endemicity and the implications of its invasive potential, this study advocates for increased research attention and proactive management strategies. Our findings fill a critical gap in the botanical literature and underscore the importance of recognizing Nechamandra alternifolia as a species of ecological and evolutionary concern.