Diverse sexual strategies in fossil gymnosperms: pollination in the Bennettitales revisited
Dawn Frame & Gerhard Gottsberger
with 3 figures and 1 table
Key words: Bennettitales, Williamsonia, Williamsoniella, Cycadeoidea, sexual system, pollination, protandry, beetles.
Frame D. & Gottsberger G. 2023. Diverse sexual strategies in fossil gymnosperms: pollination in the Bennettitales revisited. – Phyton (Horn, Austria) 62–63: 127–137, with 3 figures and 1 table.
Literature, images and anatomical slides of bennetittalean fossils were studied to gain insights into pollination biology. Our review grounded in modern concepts of floral biology and plant-animal interactions leads to new interpretations of existing data. Focusing on bisexual bennettitaleans, especially Cycadeoidea, we propose a novel explanation of how pollination occurred. Pollination was similar to an angiosperm cantharophilous syndrome, complete with pollination chamber, except that bisexual bennetittalean flowers were protandrous rather than protogynous. Small-bodied beetle pollinators arrived at the protandrous flowers just prior to or at the time of pollen release. Beetles in the pollination chamber mated and females oviposited in the androecium and larvae developed there, maturing on the ground after androecium shedding; adults later emerged from the ground litter. At the time of androecium shedding and shortly after, adult beetles carrying pollen fly to other flowers, if attracted to female-stage flowers, briefly visit and pollinate.