Comparative petiole histology using microscopic imaging visualization among Amaranthaceous taxa

Abstract

This paper described the microstructural features of the histological vasculature of family Amaranthaceae. The petiole anatomy of 14 Amaranthaceous species categorized into nine genera, including Amaranthus and Chenopodium (3 species each), Alternanthera (2 species), and Aerva, Achyranthes, Atriplex, Bassia, Digera, and Gomphrena (one species each). Amaranthaceous species were collected from different localities of the Thal desert were examined using a microscopic imaging technique. Petiole transverse segments were cut with a Shandon Microtome to prepare slides. The distinguishing features of taxonomic significance include petiole outline, vascular bundle shape, variation in the number of vascular bundles, petiole length and width, trichomes, layers of collenchyma, and the shape of parenchyma. Petiole shapes were observed as cordate, slender, spherical, and ovoid. Quantitative measurements were taken to analyze the data statistically through SPSS software. Amaranthus retroflexus had a petiole of a maximum length of 760 µm and a minimum in Amaranthus viridis 170 µm. The highest number of vascular bundles, 11 were observed in Alternanthera sessilis. The polygonal-shaped parenchyma and the annular type of collenchymatous cells were prominent. A maximum of 18 collenchyma layers were present in Achyranthes aspera and a minimum of 9 layers in Amaranthus graecizans. Trichomes were examined in six species with bulged pointed ends, and broad glandular bases. Epidermis cells also show great variation, with an irregular shape being dominant. Statistic UPGMA dendrogram and PCA clustering of petiole traits show that histological sections can be utilized to botanical identify Amaranthaceous species and play an important role in future taxonomic and phylogenic relationships.