Abstract: A kind of petrified cordaitean root-species,Amyelon taiyuanense Wang et Tian,sp.nov.is described,in coal balls from Coal Seam No.7 of Taiyuan Formation,Xishan Coal Field,Taiyuan,Shanxi Province.They have such characteristics different to the other described species of Amyelon as follows:a.plate collenchyma developed in the inner cortex;b.the existence of exodermis with suberized strip on the radial wall of the cell;c.cortex can exist for a long time.Aerenchyma similar to that of Amyelon taiyuanense sp.nov.are also found in the cortex of many modern mangroves,sruch as Rhizophora,Avicennia and Conocarpus etc.,which all live in salt and brackish swamp.So the living environment of cordaites represented by Amyelon taiyuanense sp.nov.probably is also salt or brackish swamp.This is proved by the results of sedimentary environmental analysis.