Taxonomy
Two species of Rhynia were initially described by Kidston and Lang from the Rhynie chert bed: R. gwynne-vaughnii in 1917, and R. major in 1920. A study of the vascular tissue of the two by D.S. Edwards in 1986 lead to the conclusion that the cell structure of R. major lacked secondary thickening bars seen in the xylem of R. gwynne-vaughnii, and was more like the water-conducting system (hydrome) of moss sporophytes. His conclusion was that R. gwynne-vaughnii belongs in the vascular plants, while R. major belongs among the bryophytes. Accordingly he transferred it to a new genus as Aglaophyton, leaving R. gwynne-vaughnii as the only species of Rhynia. Rhynia is the type genus for the rhyniophytes, established as the subdivision Rhyniophytina by Banks, but since treated at various ranks.
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