The family Scrophulariaceae consists of taxonomically complex genera and species. The delimitation of the taxa within this family is always challenging. In this paper, we studied leaf epidermis anatomical characteristics and its taxonomic significance of four species belonging to four genera of the family Scrophulariaceae collected from northern Pakistan. The species were examined under light and scanning electron microscopes (LM and SEM). Qualitative and quantitative foliar epidermal anatomical features were examined for both adaxial and abaxial surfaces. Qualitative characters like epidermal cell shape, epidermal cell cover, anticlinal wall, trichomes type, stomata type and stomata position were examined. Quantitative characters like the length and width of leaf epidermis, stomata, stomatal pore, subsidiary cell and trichomes for both adaxial and abaxial surfaces were studied and measured. Stomatal index within the species and between the species was found to be different on adaxial and abaxial surfaces. Diacytic stomata and glandular trichomes on epidermis were only found in Anticharis glandulosa while rest of the taxa has anomocytic type stomata and dendroid trichomes on both surfaces. Based on the micromorphological characters, we did principal component analysis (PCA), and cluster analysis for the species delimitation and identification. A taxonomic key has been provided to delimit and identify the studied taxa based on foliar epidermal characters. The aim of the present research was to elucidate the micromorphological characters to distinguish the studied taxa for taxonomic purposes.

中文翻译：

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巴基斯坦玄参科选定分类群的叶表皮解剖学分类学意义

玄参科由分类学上复杂的属和种组成。划定该科内的分类群始终具有挑战性。在本文中，我们研究了从巴基斯坦北部采集的玄参科四个属的四个物种的叶表皮解剖学特征及其分类学意义。在光学和扫描电子显微镜（LM 和 SEM）下检查物种。定性和定量叶表皮解剖特征进行了检查正面和背面。检查了表皮细胞形状、表皮细胞覆盖、背斜壁、毛状体类型、气孔类型和气孔位置等定性特征。叶表皮长宽、气孔、气孔、研究和测量了近轴和远轴表面的副细胞和毛状体。发现物种内和物种之间的气孔指数在近轴和远轴表面上是不同的。表皮上的双细胞气孔和腺毛仅见于Anticharis gunulosa而其余的分类群在两个表面上具有单核细胞型气孔和树状毛状体。基于微形态特征，我们进行了主成分分析（PCA）和聚类分析进行物种定界和鉴定。已提供分类学关键字以根据叶表皮特征来界定和识别所研究的分类群。本研究的目的是阐明微形态特征，以区分所研究的分类群以进行分类。