In the context of modern phylogenetic models , the groups often referred to as pteridosperms appear to be liberally spread across a range of clades , and many palaeobotanists today would regard pteridosperms as little more than a paraphyletic ` grade-group ' with no common lineage .
They are spread across a range of clades and many palaeobotanists today would regard pteridosperms as little more than a paraphyletic ` grade-group ' .