Tendril Anatomy and Palynological Studies of Cucurbitaceous Taxa from District Bhakkar, Punjab, Pakistan

Abstract

This research is confined to presenting taxonomic information on the family Cucurbitaceae from the District Bhakkar Punjab-Pakistan. This study elucidates the micromorphological characterization of Cucurbitaceous species adapted to arid environment were analyzed using light (LM) and scanning electron microscope (SEM). A total of 17 Cucurbitaceous taxa were categorized into 07 genera collected from March 2022 to August 2022 including Cucumis (five species), Cucurbita and Luffa (three species each), Citrullus and Momordica (two species each) while Lagenaria and Praecitrullus (one species each). Tendril transverse sections were cut with a Shandon Microtome to prepare slides. Tendril shapes observed are irregular, slightly oval-shaped, slightly C shaped, angular, and star shaped. Cucurbita pepo had a maximum tendril diameter length of 656.1 µm and a minimum in Momordica balsamina of 123.05 µm. The highest number of vascular bundles (12) were noticed in Luffa acutangula var. amara. Morphological variations in Cucurbitaceous pollen grains may aid in the delimitation of Cucurbitaceous species using visualized scanning sculptured elements patterns. Pollen grains were processed through the acetolysis technique, measured, and photographed. The pollen grains are monads, medium to large in size, shape prolate-spheroidal (nine species), oblate-spheroidal (six species and spheroidal in two species with a circular to triangular amb. Tricolporate types of the apertures analyzed in the genera are to be separated into different varieties. The pollen diameter measured maximum for the polar axis was 93.8 µm and the equatorial distance was 97.4 µm in Cucurbita maxima. Exine thickness was calculated highest at 5.9 µm for Praecitrullus fistulous. Mesocolpium ornamentation shows scabrate-reticulate, reticulate, scabrate-perforate, gemmate verrucate, baculate-echinate, reticulate-gemmate and scabrate-echinate sculptural features. Statistical UPGMA dendrogram and PCA clustering of micromorphological traits can be used to identify species and will play a vital role in future taxonomic and phylogenic linkages. A dichotomous key based on palyno-anatomical characters to the Cucurbitaceous species was also constructed. The taxonomic micromorphology of Cucurbitaceous species provides a better understanding of their systematics and plays a significant role in their accurate identification. The purpose of this study is to provide an overview of the tendril microanatomical and pollen morphological features as a foundation for future research at the molecular systematic level.