Investigation on the stipe morpho-anatomical traits in some members of Pteridaceae and its Taxonomic relevance

The vascular arrangement of fern and fern-allies has been a source of great fascination for botanists since the nineteenth century to modern times. The study of stipe anatomy has been accepted to be of great taxonomical value and the patterns of organization and vasculature in ferns is a great point for comparative study. The morpho-anatomical traits of fern stipes provide essential insights into fern systematics and phylogenetics. This study explores the morpho-anatomy of stipes in 24 species of Pteridaceae span under four subfamilies, Pteridoideae, Vittarioideae, Cryptogrammoideae, and Cheilanthoideae, collected from the eastern Himalayan region. The morphological traits such as stipe length, colour, surface texture, and scale characteristics were systematically examined. Concurrently, anatomical investigations revealed variations in stipe outlines, vascular bundle shapes, and xylem strand configurations.

The study highlights significant interspecific variability, with vascular bundle ranging from U to inverted Ω shaped, and xylem strands adopting diverse morphologies such as V, U, and hippocampus-shaped configurations. These anatomical traits show potential taxonomic and phylogenetic value, aiding in species delineation, particularly in cases where morphological features overlap due to convergent evolution.

Additionally, the study confirms the presence of consistent sclerenchymatous epidermal layers across species, reinforcing the adaptive role of these structures in their ecological niches. The findings emphasize the importance of stipe anatomy as a reliable tool for taxonomic delineation, enhancing the understanding of evolutionary relationships within Pteridaceae.