PJB-2004-76
POLLEN MORPHOLOGY AS AN AID TO THE IDENTIFICATION OF SCORZONERA (CICHORIEAE-COMPOSITAE) FROM PAKISTAN
AKBAR ALI MEO AND MIR AJAB KHAN
Abstract
Pollen morphological characters of 5 species of Scorzonera have been investigated from Pakistan by light microscopy. Pollen grains are usually radially symmetrical, isopolar, prolate-spheroidal in equatorial view, semi-angular to inter-semi-angular in polar view, trizonocolporate, non-lacunate and echinate. Pollen characters such as size, shape, colpi and exine thickness, and aperture type are found considerably important. Scorzonera hondae can be distinguished due to its sub-prolate shape whereas S. picridioides has oblate-spheroidal subprolate P/E ratio (0.95). The pollen spine character is a diagnostic character in this genus. S. hondae has the highest spine length (4.8 µm) and S. laciniata can be distinguished due to lowest spine length 2.5 µm. There is a great range of variation in exine thickness which has proved useful at specific level. On the basis of exine thickness 3 groups viz. Group 1: S. virgata, S. laciniata, Group II: S. picridioides, Group III: S. ammophila, S. hondae are recognized.
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