European Palaeobotany and Palynology Conference 2026

The diversification of epiphytic and climbing plants during the late Paleozoic has commonly been linked to the development of densely vegetated swamp forests dominated by marattialean tree ferns that formed relatively closed canopies. Within the early Permian Wuda Tuff Flora, the zygopterid fern Nemejcopteris haiwangii was previously interpreted as a ground-cover plant characterized by a rhizomatous stem and upright phyllophores bearing primary pinnae arranged perpendicular to the frond plane. Although hook-like prickles on its axes had been suggested to aid climbing, unequivocal fossil evidence supporting such a growth habit has remained unavailable. Here we report several exceptionally preserved specimens that document direct physical associations between the fronds of N. haiwangii and trunks of Psaronius, demonstrating that this fern used tree hosts for climbing support. The prickles distributed along the axes indicate a hook-assisted climbing mechanism; however, their limited size and rigidity suggest that the species possessed only weak climbing capabilities and was probably unable to ascend into the upper canopy. Considering the sedimentological and ecological setting of the peat-forming swamp environment, we infer that the evolution of climbing in N. haiwangii may have represented an adaptation to periodic submergence rather than a strategy primarily driven by light competition. This interpretation provides an alternative explanation for the remarkable abundance and diversity of climbing plants in late Paleozoic coal-swamp ecosystems.