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Zosterophyllum longa sp.nov.is reported from the Lower Devonian Pingyipu Formation, Jiangyou District,northern Sichuan of China.This new plant has vertically elongate sporangia differing from all known species of Zosterophyllum,demonstrating morphological variations in Zosterophyllophytina.New materials of Zosterophyllum yunnanicum from the Lower Devonian Xujiachong Formation,Qujing District,eastern Yunnan of China show that fertile axes of this species are anisotomous or pseudomonopodial or K-shaped in branching.Sometimes fertile lateral axes are very short and bear an axUlary axis at the dividing point.Distinct thickening occurs along the whole margin of a sporangium,with sporangial lobes undeveloped.The evolution of Zosterophyllum is tentatively discussed.A biostratigraphic method of Gerrienne and Streel is introduced and applied to dating of the Lower Devonian Xujiachong Formation,which is considered as of the late Pragian-early Emsian.
Zosterophyllum longa sp. Nov.is reported from the Lower Devonian Pingyipu Formation, Jiangyou District, northern Sichuan of China. This new plant has vertically elongate sporangia differing from all known species of Zosterophyllum, demonstrating morphological variations in Zosterophyllophytina. New materials of Zosterophyllum yunnanicum from the Lower Devonian Xujiachong Formation, Qujing District, eastern Yunnan of China show that fertile axes of this species are anisotomous or pseudomonopodial or K-shaped in branching. Sometimes fertile lateral axes are very short and bear an axUlary axis at the dividing point. Distinct thickening occurs along the whole margin of a sporangium, with sporangial lobes undeveloped. The evolution of Zosterophyllum is tentatively discussed. A biostratigraphic method of Gerrienne and Streel is introduced and applied to dating of the Lower Devonian Xujiachong Formation, which is considered as of the late Pragian -early Emsian.