Ontogeny and ecology of the filicalean fern Oligocarpia gothanii (Gleicheniaceae) from the Middle Permian of China

Reinvestigation of Oligocarpia gothanii Halle (Gleicheniaceae) from the Permian Period of China has uncovered a rare demonstration of ontogenetic succession in numerous intact plants and has led to emendation of the diagnosis and typification of the species. Reconstruction of the fern's vegetative life cycle shows a small rosette‐shaped juvenile plant with immature fronds of pinnae undifferentiated into pinnules. The second stage is a series of leafy shoots increasing in size and complexity and bearing fronds essentially comparable with those of the adult plants. Mature plants have sphenopteroid‐type fronds differentiated into vegetative and fertile fronds. Close association of plants on the same bedding plane and the presence of a connecting root network between shoots, show that juvenile plants spread by vegetative propagation using underground stolons. Sedimentological information and co‐occurrence with the bryophyte Thallites hallei Lundblad suggests that O. gothanii occupied a wetland habitat and was preserved in an obrution event consistent with flooding of marginal areas in a fluvio‐deltaic setting. Although recent studies on Oligocarpia have focused exclusively on reproductive features, new ontogenetic information suggests that plants growing in rapidly changing environments may have been reliant on vegetative propagation and would not have needed to reach sexual maturity for successful reproduction.