Homoploid Hybridization between Native Salix cavaleriei and Exotic Salix matsudana (Salicaceae) Molecular evidence for natural hybridization between Rhododendron spiciferum and R. spinuliferum (Ericaceae) Molecular Evidence for Bidirectional Hybrid Origin and Hippophae rhamnoides ssp. sinensis as the Mainly Maternal Plant of the Diploid Hybrid H.goniocarpa(Elaeagnaceae) Phylogenetic and cytogenetic studies reveal hybrid speciation in Saxifraga subsect. Triplinervium (Saxifragaceae)