Research Paper

Pollen morphology of the Galium L. (Rubieae-Rubiaceae) from Pakistan and evaluation of its systematic significance

Tariq Ullah, Amjad Khan, Raees Khan, Amir Sultan, Shahab Ali, Mohsin Kazi

Published on: 19 March 2025

Page: 207 - 218

DOI: 10.6165/tai.2025.70.207

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    Abstract

    Galium is a typical member of the tribe Rubieae, characterized by its 3 or 4-lobed corolla, rudimentary corolla tubes, corolla tube length and dry mericarps and has a ubiquitous distribution. In this study pollen morphology of 20 species of Galium from Pakistani highland was investigated and documented in detail using light and scanning electron microscopy. The genus Galium itself is a delimited natural group and its taxa are poorly explored for pollen morphology. Among the investigated species, pollen grains are small to large (P=13.05–21.75 μm, E=17.00–24.20 μm), oblate–spheroidal, suboblate, subprolate and prolate–spheroidal (P/E=0.84–1.16) in shape and 5–10 colpate. Exine sculpturing under SEM showing different ornamentations, including microechinate–scabrate, scabrate–punctate, microreticulate–scabrate, microspine–scabrate, microechinate–punctate, microspine–verrucate, microechinate–verrucate, microspine–perforate, scabrate–verrucate and microechinate–perforate among the investigated taxa. In addition, based on pollen morphometric traits, hierarchical clustering (UPGMA) analysis is performed for correlation between the species. However, pollen traits alone or with the combination of morphological characters are used in the infrageneric relationships and also provide useful information for its evolutionary history.

    Keyword: Galium, Pakistan, Palynotaxonomy, SEM, UPGMA

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