Permotheca with in situ pollen grains from the Lower Permian of the Urals

Abstract

Sporangial heads or the pollen organ Permotheca from the Lower Permian or Tschekarda, the Urals, are described as semisynangiate, with sporangia proximally connate for about one-third to half their length. The sporangial walls are three-layered and vascularized. The pollen grains, studied with LM, SEM and TEM, are transitional protomonosaccale-bilobed to protobisaccate, sulcate, with alveolar infrastructure lamellate nexine and a tryphine-like surface layer. Chilrid zoosporangia occur in the pollen grains. The similarity to Idanothekion in the sporangial and pollen morphology may indicate phylogenetic relationships.