Systematics and Phytogeography of Angiospermic Floral Diversity in Baluchistan, Pakistan

Abstract

The systematics of angiospermic flora of Baluchistan, Pakistan was first time investigated in this study. The collection of the angiosperms was carried out via field trips in different areas of Baluchistan including Loralai, Uthal, Bela, Hingol National Park, Hazar Ganji Chiltan National Park, Quetta, Ziarat, Quetta, Kalat, Mastung, Pathankot, Qillasaifullah, Sanjavi, and Zhob. The details of phytogeography with photographs were documented for 108 angiosperms belonging to selected three families including Asteraceae, Boraginaceae, and Poaceae, as leading groups based on the number of species collected. The pollen micromorphological characterization was carried out via light microscopy (LM) and scanning electron microscopy (SEM). The petiole and culm transverse sections were prepared using microtomy, and their anatomical traits were studied via light microscopy. The data of quantitative measurements of the palynological and anatomical traits was collected into a matrix and analyzed statistically via SPSS (2016), Past (2021), Origin (2023), and NCSS (2023). The polar axis was maximum 88.15μm in Chloris barbata and minimum 13.2μm in Paracaryum intermedium var. intermedium. The largest equatorial diameter 90.75μm was observed in Chloris barbata. Gymnarrhena micrantha pollen was noted with minimum 3.3μm equatorial diameter. Among the examined petioles, the minimum length 18.3μm and width 13.75μm of vascular bundles were noted in Leuzea repens. The maximum width 302.1μm and length 250.85μm of vascular bundles were observed in Alkanna tinctoria subsp. Tinctoria and Launaea aspleniifolia respectively. The significantly varied palynological features among Asteraceous taxa were shape (prolate spheroidal, oblate spheroidal, suboblate, subprolate, and prolate), heterogeneity in the number of apertures (tricolpate, tricolporate, tetracolpate, tetracolporate), variations in polar and equatorial views from circular to triangular obtuse convex and elliptic), exine (echinate, lophate, scabrate, perforate or non-perforate), lacuna shape, number of spines per pollen, number of spines between colpi, spine length, and width. Boraginaceae was found eurypalynous family in terms of pollen traits variations, and the significant palynological features such as differences in polarity (isopolar or heteropolar), colpi type (isocolpate or porocolpate), exine (psilate, scabrate, gemmate, and foveolate), aperture membrane (smooth, granulate, operculate), Amb (goniotreme, peritreme, and ptychotreme), and shape (prolate spheroidal, oblate spheroidal, suboblate, subprolate, and prolate) were found taxonomically important in the identification of taxa. While xviii the Poaceous pollen were stenopalynous when characterized, although there were differences in the shape (prolate spheroidal, oblate spheroidal, suboblate, subprolate, and prolate), degree of harmomegathy, annulus appearance, and pore orientation sunken or prominent. The largest polar axis was observed in Chloris barbata 88.15μm. P. intermedium var. intermedium was observed with smallest polar axis of 13.2 μm. The systematically useful petiole anatomical features that differentiated the taxa up to the species level were petiole outline (sulcate, round, flat, oval), vascular bundles number and arrangement (collateral closed, collateral open bicollateral and amphicribral), collenchyma (angular, lamellar, annular, and lacunar), cuticle (smooth or undulated), trichomes (unicellular, uniseriate, and multiseriate), wings, and groove in the surface. The important culm anatomical traits of grasses were culm shape (terete, quadrangular, semi-terete, elliptical, bundle sheath composition, number, and arrangement of major and peripheral vascular bundles, central and marginal cavities, and sclerenchymatous hypodermis. The Principal Component Analysis (PCA), dendrogram, correlation, and normal probability distribution plot successfully separated the taxa of each family. The pollen micromorphological and petiole/culm anatomical traits were used as taxonomic markers to develop the taxonomic keys for the delimitation of studied angiospermic flora. The distinguished palynological and anatomical characters provide the base for the identification of angiospermic flora.