Article: Palaeosmunda, a new genus of siphonostelic osmundaceous trunks from the Upper Permian of Queensland

Petrified osmundaceous trunks from the Upper Permian coal measures of the Bowen Basin, Queensland, are assigned to a new genus, Palaeosmunda, which possesses an ectophloic, sometimes almost simple but usually dictyoxylic, siphonostele with parenchymatous pith; the stems bear stipulate petiole bases which contain sclerotic rings that are rhomboidal in transverse section, upwards becoming laterally extended into flanges. These are the first Permian Osmundaceae definitely known to exhibit a distinct pith and leaf gaps. A table of morphological comparisons of all known Permian osmundaceous axes is presented. Discovery of Palaeosmunda indicates that the family had a greater structural diversity and a wider geographic distribution in the Upper Permian than was previously realized; and hence the Osmundaceae probably developed before the Permian. Two species, P. williamsii (type species) and P. playfordii, are described in detail; the inner cortex, and sometimes the stipules of the petiole bases of P. williamsii contain strands of sclerenchyma, while stipules and inner cortex of the petiole bases of P. playfordii consist only of parenchyma. Evidence from association indicates that the trunks probably bore fronds of the types referred to Sphenopteris lobifolia Morris 1845, S. polymorpha Feistmantel 1876, and Cladophlebis roylei Arber 1901.