Stomatal development in the cycad family Zamiaceae

Abstract Background and Aims The gymnosperm order Cycadales is pivotal to our understanding of seed-plant phylogeny because its phylogenetic placement close the root node extant spermatophytes combination both derived plesiomorphic character states. Although widely considered a ‘living fossil’ group, cycads display high degree morphological anatomical variation. We investigate stomatal development in Zamiaceae evaluate variation within homologies between other seed plants. Methods Leaflets seven species across five genera representing all major clades were examined at various stages using light microscopy confocal microscopy. Key Results All have lateral subsidiary cells perigenous origin that differ from pavement mature leaflets could role physiology. Early epidermal patterning ‘quartet’ arrangement occurs Ceratozamia, Zamia Stangeria. Distal encircling cells, which are sclerified maturity, present except Bowenia, shows relatively rapid elongation differentiation during leaflet development. Conclusions Stomatal structure highlights some traits plants, including presence reveals clear difference developmental trajectories Bennettitales. Our study also an unexpected among subclades family, potentially linked differences suggesting convergent evolution cycads.