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.[2] 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.

Callistophytales Temporal range:
Reconstruction of the plant Callospermarion pusillum (permineralized ovules), Idanothekion callistophytoides (pollen organ), Dicksonites pluckenetii (leaves), Callistophyton poroxyloides (stem), and Vesicaspora shaubergeri (pollen) from the Pennsylvanian Calhoun Formation of Berryville, Illinois.[1]
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Division:	†Pteridospermatophyta
Class:	†Lyginopteridopsida (?)
Order:	†Callistophytales G.W.Rothwell 1981, emend. 1982
Families
Callistophytaceae Emplectopteridaceae

The inclusion of the Callistophytales within the Lyginopteridopsida is controversial because of the apparent sophistication of the ovules and pollen.[3] There are nevertheless many other characters that suggest that the Callistophytales is derived from a more primitive lyginopterdalean-like ancestor, including the presence of a lagenostome at the apex of the nucellus, the general structure of the pollen organs, and the overall morphology of the vegetative structures.

Two families have been recognised: the Callistophytaceae, known mainly from the Carboniferous floras of Euramerica; and the Emplectopteridaceae, known mainly from the Permian floras of China and adjacent areas.