The rooting system of Leptophloeum Dawson: New material from the Upper Devonian, Famennian Witpoort Formation of South Africa

•We document the rooting system of Leptophloeum rhombicum.•The rooting system of Leptophloeum is not of the Stigmaria-type.•We discuss the generic validity of Leptophloeum.•We interpret the basal portion of the plant as a transitional zone.

The rhizomorphs of Early (Devonian and Early Carboniferous) arborescent lycopsids are known from only a handful of taxa. That of Leptophloeum is previously described from a single fragmentary specimen from China that, in our opinion, has been incorrectly interpreted. Here we describe several relatively well-preserved examples of Leptophloeum rhizomorphs from the Famennian aged Waterloo Farm Lägerstatte of South Africa. We demonstrate an unlobed cormose morphology separated from the microphyll bearing axis by a smooth transition zone. This provides one of the few known examples of a cormose lycopsid rhizomorph dating back to the Devonian. We assign this material and all previously published South African Leptophloeum material to Leptophloeum rhombicum.