PJB-2006-3
POLLEN MORPHOLOGY AS AN AID TO THE IDENTIFICATION OF CHRYSANTHEMUM SPECIES (COMPOSITAE-ANTHEMIDEAE) FROM PAKISTAN
AKBAR ALI MEO AND MIR AJAB KHAN*
Abstract
Pollen morphology of 7 species of Chrysanthemum has been examined from Pakistan by light and scanning electron microscopy. The pollen grains in all the species are trizonocolporate. Pollen shape in polar view is circular, inter-semi-angular and semi-circular to angular. Pollen is spheroidal, sub-spheroidal, oblate-spheroidal and prolate-spheroidal in equatorial view. Taxa of Chrysanthemum species can be distinguished by pollen size, exine thickness, spine length and number of spine rows between colpi. Chrysanthemum indicum has characteristic spines having a broad flattened base with grooves. C.stoliczkai has the small spine length (3.3 m) while C. indicum can be characterized by long spine length (5.9 m) and C. tibeticum can be distinguished due to lowest number of spine rows between colpi (3-4). Chrysanthemum stoliczkai and C. parthenium are determined by long exine thickness (7.9 m) and (9.5 m) within the genus. This study demonstrates the potential of pollen studies in distinguishing some taxonomic groups in Anthemideae. There is great range of variation in exine thickness which has proved useful at specific level. On the basis of exine thickness, 4 groups viz., Group I: C. tibeticum, Group II: C. indicum, C. segatum, Group III: C. leucanthemum, C. murifolium and Group IV: C. stoliczkai, C. parthenium are recognized.
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