Do pollinators influence seed‐set in Banksia paludosa Sm. and Banksia spinulosa R. Br.?

Abstract

AbstractThe consequences of observed variations in pollinator activity for plant reproduction depend on the breeding system of the plant and also on whether pollination is a resource in short supply. These factors are frequently assumed rather than tested. In bagging experiments with Banksia paludosa in heath and B. spinulosa var. spinulosa in woodland, the present study demonstrated that seed‐set does not occur by autogamy and that pollinators are indeed necessary. Experimental addition of outcrossed pollen to inflorescences failed to produce any increase in the mean number of seeds per inflorescence, measured for non‐barren inflorescences, for either species. However, in B. paludosa, the addition of pollen increased the numbers of inflorescences that set seed from 20% (controls) to 45% (pollen‐added treatment). This suggests either unusual patterns of pollen movement among and within plants or control of the pattern of seed‐set within a plant. Pollen additions failed to alter seed‐set in B. spinulosa. It is possible that a greater abundance of pollinators in the woodland ensures adequate pollination for these plants