The new plants documented here, including a representative of the trimerophytes Psilophyton primitivum sp. nov., a questionable rhyniophyte or trimerophyte Hedeia sinica sp. nov., a prelycopod Baragwanathia sp. and two species of zosterophyllophytes, Zosterophyllum australianum Lang and Cookson 1930 and Z . sp.1, from the Posongchong Formation of southeastern Yunnan, China, add to the known floral diversity of the Early Devonian of this region. Two sections of the Posongchong Formation, Changputang section of Wenshan district and Gegu section of Mengzi district also are introduced. After comparing the plants with those of the coeval flora of Australia and considering the data of recent paleocontinental reconstructions, the authors suggest that there is a northeastern Gondwana phytogeographic unit during the early Devonian comprising Australia, South China Block and perhaps Shan Thai Block. The similarity of the floral component between Australia and South China is discussed. Because both Australia and South China also have dominant or endemic taxa, each might be recognized as a subunit, separately characterized by Hedeia for Australia and Eophyllophyton for South China.
