Callistophytales

The Callistophytales was an order of mainly scrambling and lianescent plants found in the wetland "coal swamps" of Euramerica and Cathaysia. They were characterised by having bilaterally-symmetrical, non-cupulate ovules attached to the underside of pinnules that were morphologically similar to the "normal" vegetative pinnules; and small compound pollen-organs, also borne on the underside of unmodified pinnules, that produced saccate pollen. They were reproductively more sophisticated than most other Palaeozoic pteridosperms, some of which they seem to have out-competed and replaced in the "coal swamp" vegetation during Late Pennsylvanian and Permian times.