Résumé
We review progress made during the last 25 years in our understanding of the Protopityales, Early Carboniferous plants belonging to the extinct group of the progymnosperms. Recent studies support previous observations that the only genus of this order, Protopitys, included large arborescent plant with trunks up to 1 m in diameter. All branch orders had an oval eustele, secondary xylem with small rays and tracheid pitting ranging from circular bordered to scalariform bordered, and vascular traces to lateral appendages emitted in an alternate to subopposite distichous arrangement. Leaf morphology remains unknown. New material also confirms that fertile organs of Protopitys consist of branching systems bearing elongated sporangia terminally. Spores have a perispore and range in two size groups, which has been interpreted as a primitive stage of heterospory. The dense wood and fertile parts of Protopitys are comparable to those of the aneurophytalean progymnosperms of the Devonian, but Protopitys is distinct by its eustelic primary vascular system, and its affinities are still uncertain. The genus is now documented from at least nine localities in Europe, North America and Australia. Recent discoveries also indicate that it was present through the whole Mississippian, from the middle Tournaisian to the Serpukhovian.