The mitochondrial DNA nad1 sequence variation of Picea crassifolia(Pinaceae) in the Qinghai-Tibetan Plateau platform and adjacent populations Phylogeography of Juniperus przewalskii (Cupressaceae) inferred from the chloroplast DNA trnT-trnF sequence variation Phylogeography of Angelica nitida (Apiaceae), an endemic to the QinghaiTibet Plateau Demographic Genetic Structure of Cryptomeria japonica var. sinensis in Tianmushan Nature Reserve, China