Archaic nature of seed plants from the Shennongjia World Natural Heritage Site, China

To study the floristic and origin characteristics of seed plants from the Shennongjia World Natural Heritage Site (SNJWNH), a time tree was established based on Phylomatic. Furthermore, the temporal characteristics of the origin of the genera in this area were discussed based on multidisciplinary evidence. Results showed rich gymnosperm diversity in SNJWNH, accounting for 67% and 74% of the total genera and species from the diverse mountainous regions in Central China. The proportion of basal families of angiosperms in SNJWNH was also high, reaching 85% of the total basal families in China. Monotypic families (containing only one genus and one species) in SNJWNH accounted for 42% of the total monotypic families in China. Furthermore, SNJWNH also possessed 56 genera endemic to China, accounting for 23% of the total endemic genera in China. The genera belonging to the East Asian and North American disjunctive distribution pattern in SNJWNH accounted for more than 50% of the total number of that floristic type in China. These results show that the seed plants of SNJWNH exhibit characteristics of ancient origin, and have continuous lineages lasting for a long evolutionary history. In conclusion, the seed plants of SNJWNH are critical to its value, and are of considerable importance to plant systematic and phylogenetic studies.