ANEMOPHILOUS PLANTS SELECT POLLEN FROM THEIR OWN SPECIES FROM THE AIR

In wind-tunnel experiments, Niklas (1985) has demonstrated the ability of anemophilous plants to select pollen from their own species from t he airstream. However, there have been no field experiments to establi sh whether this operates in nature. We surveyed the pollens on the sti gmas of four different, coextensive, dioecious anemophilous species su rrounded by a Pinus radiata plantation. The alien pine pollen was over represented relative to background levels on only one of the four spec ies. For all three indigenous species with both male and female plants in the area, the highest proportion - in all cases more than 40% - of the pollen found on their stigmas came from their own species. One in digenous species lacked male plants in the area; consequently, the res ults from this species are difficult to interpret. However, for all fo ur species, there was at least 15% pine pollen, and some pollen of oth er indigenous species. These results suggest that there is some pollen selection, but that the mechanisms are maybe not as effective as Nikl as has suggested.