Morphological Study on Some Taxa of Myoporaceae and Scrophulariaceae

Abstract

The taxonomic relationship between Myoporaceae and Scrophulariaceae has long been debated, historical systems kept Myoporaceae as a distinct family but combined morphological and” especially molecular evidences” resulted in the treatment of the Myoporaceae as a part of Scrophulariaceae. This study investigates the taxonomic delimitation between these families by examining macromorphological characters of the whole plant and micromorphological features of the stem, lamina, and flower. Six species from both families (three representing Myoporaceae and three representing core Scrophulariaceae) were collected and investigated using light microscopy to assess the diagnostic traits. A sum of 47 macro-and micromorphological traits was compiled into a comprehensive matrix and statistically analyzed using R software to evaluate the degree of similarity and potential phylogenetic closeness between the two families. Results revealed significant differences mainly in (plant habit, fruit type, number of ovules, mesophyll tissue, secretory system, and trichome types), which support the distinct separation of the two families. In contrast, the considerable similarity in floral vasculature patterns suggests a possible merger of the two families. Furthermore, the taxonomic placement of Leucophyllum frutescens is noteworthy, as it exhibits a high degree of similarity to the family Myoporaceae.