This study presents a critical comparison of the vegetative anatomy and morphology of “compression species” and “petrifaction species” of Sphenophyllum. There are many similarities between both groups, but also some marked differences, which cannot be accounted for by the different modes of preservation. Whereas the “compression species”, or a majority of them, are to be reconstructed as scramblers, the “petrification species” probably had prostrate, rooting main axes from which aerial branch systems arose. Sphenophyllum appears to show that the assumption that compressions and petrifactions would be different manifestations of the same plant species is not always justified.