W. J. Jongmans, a botanist, was drawn into the study of Carboniferous compression floras for stratigraphic purposes. He was the founder and director of the Geological Bureau in Heerlen, Netherlands Limburg, where he organized four highly successful international congresses on Carboniferous stratigraphy and geology. Although starting out with a clear commitment to the monographic description of the Carboniferous flora of The Netherlands, he became increasingly drawn into a worldwide documentation of Carboniferous compression floras. These were also used for floral biogeography. His encyclopedic knowledge of the paleobotanical literature was due in part to his prodigious efforts to compile the Fossilium Catalogus—Plantae, an indispensable work of reference for the paleobotanical taxonomist. He also furthered palynological and coal petrographic studies.