PJB-2006-57
PALYNOLOGICAL OBSERVATIONS ON THE GENUS CALENDULA (CALENDULEAE-COMPOSITAE) FROM PAKISTAN
AKBAR ALI MEO AND MIR AJAB KHAN*
Abstract
The pollen morphology of Calendula species was investigated by light and scanning electron microscopy. Pollen grains are prolate-spheroidal in equatorial view and semi-angular in polar view, tri. to tetrazoncolporate, caveate and echinate. Size of polar axis and equatorial diameter, exine thickness, spine length are presented. Variation exists at species level i.e. exine thickness is higher in C.arvensis L. (6.3 µm) as compared to C.officinalis L. (3.3 µm). Existence of simple and closely placed pair of spines are highly diagnostic in Calendula. In C. officinalis spines are mostly paired and in C. arvensis mostly simple but closely placed pairs of spines also exist.
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