INSECT AND WIND POLLINATION IN SAUX REPENS L. AND SAUX CAPREA L.

ABSTRACT

It is widely accepted that the Salices of western and central Europe are predominantly entomophilous, but there are indications suggesting a distinct role of air currents in pollination as well. In the present study, this point was experimentally approached by encasing female catkins of Salix repens L. and S. caprea L. in net covers, thus rendering them unapproachable to the habitual insect visitors without hampering the access of airborne pollen. Afterwards, their seed set was compared with that of uncaged control catkins. Seed set attributable to wind pollination in S. repens amounted to 70% in one location and to 20% in another location, while that in S. caprea it came to 50%. An investigation into the pollen aggregation tendency proved that the pollen stickiness of S. repens is slightly lower than that of S. caprea. Taking into account the combined evidence, S. repens appears to be somewhat better adapted to wind pollination than S. caprea, while the contrary applies to insect pollination. Since both air currents and insect visitors substantially contribute to pollen transfer, the pollination system of both Salix species should be designated as ambophilous.