The Xichong flora of Yunnan, China: diversity in late Mid Devonian plant assemblages

Over the past 10 years, significant progress has been made in our understanding of late Mid Devonian floras of Yunnan Province, China. Based on new collections and a restudy of existing specimens, most of the old taxa have been emended, and some new taxa described. The late Mid Devonian Xichong flora of Yunnan is dominated by lycopsids, including prelycopsids, homosporous and herbaceous protolepidodendrids. The ‘fern’-like and cladoxylopsid plants are important and are mainly endemic. A few small plants have also been reported. The Xichong flora is divided into two ecological levels: small tree and ground cover levels. The palaeoclimate of late Mid Devonian Yunnan belonged to the tropical zone. There are noticeable differences between the fossil plants of Yunnan and those of the late Mid Devonian in Laurussia and Venezuela. The Xichong flora is a special, endemic flora in a palaeogeographically isolated tropical area, controlled by local palaeoclimate. The sequence of floras developed in pre-Carboniferous time in South China includes the Posongchong (Pragian), the Xichong (late Givetian) and the Wutung (late Famennian) floras. These floras are treated as pre-Cathaysian floras. Further work is required to establish how much influence these pre-Cathaysian floras had in the Carboniferous-Permian development of the Cathaysian Flora