INVESTIGATIING THE ASSOCIATION OF MORPHOMETRIC POLLEN TRAITS OF VARIOUS ECHIUM SPECIES WITH POLLEN-VISITOR INSECT, APIS MELLIFERA IN JORDAN

Three Echium (purple bugloss) species were investigated palynologically by (LM) and (SEM). The three Echium species have 3- or 4-zonocolporate pollen class. Polar measurements ranged between 36-45 μm. E. angustifolium Miller had the smallest polar measurements (36–42 μm), While E. glomeratum Poiret and E. judaeum Lacaita had polar measurements in the range of 40–45 μm and 41–44 μm, respectively. Equatorial measurements ranged between 28-35 μm for E. angustifolium, 29-35 μm for E. glomeratum and 29-34 μm for E. judaeum. P/E ratio ranged between 1.5–1.42 for E. angustifolium, 1.42–1.30 for E. glomeratum and 1.43–1.25 for E. judaeum. The results regarding pollen outline indicated that the equatorial view for all Echium species was rectangular-elliptic; whereas, the polar view was triangular. P/E ratio was erect for all species examined. The morphology of ectoaperture structures (colpi, fastigium and margins) had reflected no variation. The three species exhibited short colpi with distinct to indistinct margins. The morphology of endoaperture structures (colpi, costae and margins) had reflected distinguished variation. Echium species had short colpi in general. Costae and margins showed some kind of variations. Honey bees (Apis mellifera) was the most observed and abundant especially on the flowers of Echium species in April due to presence of certain pollen-insect associations. Pollen grains of Echium species are considered to have a specialized relationship with some pollen visitors although having pollen and nectar as rewards for all pollen visitors. This kind of interaction between Echium species with specific pollen visitors (A. mellifera) found associated with morphometric characteristics of pollens, pollen-nectar as rewards to pollen visitors. Seasonality is considered as the ultimate factor reflecting different observed patterns of visitor distribution among plant flowers for the collection of pollen-nectar since Echium is producing a large amount of nectar and pollinferous material.