Abstract
The present study highlights the taxonomic values of the pollen features of 20 species of Verbascum L. in Iraq. The pollen grains were acetolysed and observed under Light and Electron microscopes. Our results showed that the pollen grains of these species are usually radially symmetrical, isopolar, tricolporate and display reticulate sculpturing. The variations were found in shape, size, and exine thickness. Most of the species are subprolate, prolate spheroidal, and prolate, whereas oblate spheroidal pollens were found only in V. thapsus. The pollen size among the species studied ranges from 16.2-32.5 µm. The majority of species are medium sized except V. agrimoniifolium and V. oreophilum that are small sized, and four species i.e. V. palmyrense, V. sinuatum, V. songaricum, and V. thapsus having both small and medium sized pollen grains. Moreover, the result showed that the exine thickness ranges from 0.87-4.75 µm, but this value can overlap between some species. Therefore, only the shape of pollen grains could be used to classify these species into groups.DOI: http://dx.doi.org/10.3329/bjpt.v21i2.21355Bangladesh J. Plant Taxon. 21(2): 159-165, 2014 (December)
Highlights
The genus Verbascum L. (Scrophulariaceae) is mostly herbaceous with few shrubs and climbers, comprises about 350 species, and it is distributed all over the world (Zohary, 1974)
Despite pollen morphology of Verbascum species was studied by several authors (Erdtman, 1952; Filippini et al, 1990; Perveen, 1993; Lobin and Pormbski, 1994; Bukhari and Alfarhan, 2006; Kheiri et al, 2006; Pehlivan et al, 2008), the pollens of Verbascum found in Iraq has never been investigated
For Light microscope (LM) analysis, the acetolysed pollens were placed in a small vial, and 5-7 drops of silicone oil were added, and the samples were mounted on a glass slide sealed with paraffin and observed under light microscope
Summary
The genus Verbascum L. (Scrophulariaceae) is mostly herbaceous with few shrubs and climbers, comprises about 350 species, and it is distributed all over the world (Zohary, 1974). In Iraq, Verbascum is represented by 26 species (AL-Rawi, 1964; AL-Bermani, 1981). The taxonomy of Verbascum species in Iraq is still uncertain, especially that as related to the geographical distribution of the species, the morphological variation and the condition of herbarium samples (AL-Bermani, 1981). Pollen morphology is proved to be a useful character for improving the accuracy in the identification and classification of several plant groups (Erdtman, 1952; Rajbhandary et al, 2012; Özler et al, 2013; Sawar and Takahashi, 2013). This study was designed to investigate constant and diagnostic pollen morphological characteristics to be used as a tool for improving the accuracy in the identification and classification of Verbascum, and further authentication of the taxa
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