Ultra-sculpturing of nutlet morphology and its taxonomic significance for identifications of Boraginaceae species

Abstract

The taxonomic significance of both micromorphological and macromorphological features of nutlets within 20 species of Boraginaceae was studied through the utilization of a stereomicroscope and scanning electron microscope (SEM) from Pakistan. The study aimed to determine distinct ultra-structural traits of nutlets with diagnostic value, contributing to the exact identification, proper delimitation, and elucidation of their evolutionary position. Boraginaceae has a wide spectrum of remarkable micromorphological traits and extremely variable ultrastructure. SEM analysis was used to investigate nutlet micromorphological features, such as color, shape, cell outline, texture, surface sculpturing, epidermal cell arrangement as well as anticlinal and periclinal walls. The seed shapes have been identified as pyramid, kidney-shaped, spherical, ovoid, ovate, and oblong with a terminal visible hilum in most taxa. The nutlets color were grey to brown, brown, black, brown to black, greenish-brown, light-brown, yellow to brown, dark brown, and mustard brown. Exo-morphological features, such as epidermal cell arrangements including rectangular, polygonal, irregular, and pentagonal to hexagonal. To evaluate comparable and dissimilar species within Boraginaceae taxa with a valid justification, cluster analysis was utilized. The nutlet morphology of taxa was examined by utilizing a stereomicroscope and SEM to evaluate the diagnostic value of the characters. At the species level, this investigation explored nutlets features which could deliver lots of new taxonomic insights. The findings showed that nutlet morphology by using an SEM could potentially be exploited in the identification of plant taxa, specifically at the genus and species level.