noted in E. hyemale. Subgeneric placement This species possess characters from both present day subgenus. It shares with the Equisetum genus the rounded strobilar apex and the dimorphic habit. It shares with the Hippochaete subgenus its dimorphic habit, the absence of branches, and the presence of pagoda structures. This species also shares characters with both subgenus at the same time, such as the position of stomata and the absence and presence of leaf tips. As Equisetum thermale, another Jurassic fossil Equisetum from Argentina, E. dimorphum shows a combination of characters from both living subgenera, Equsietum and Hippochaete. There are two other Equisetum'' species, very similar to E. dimorphum, that also possess this mosaic of characters, and perhaps the three species belong to a previously unidentified fossil subgenus. References dimorphum Jurassic plants Prehistoric plants of South America Jurassic Argentina Flora of Argentina Fossils of Argentina Fossil taxa described in 2015 Plants described in 2015