MATERNAL DIVERGENCE AND PHYLOGEOGRAPHICAL RELATIONSHIPS BETWEEN HIPPOPHAE GYANTSENSIS AND H. RHAMNOIDES SUBSP. YUNNANENSIS Characteristic of Molecular Evolution of Sibiraea angustata Based on nrDNA ITS and cpDNA trnL-F Sequence Analysis Molecular phylogeny of Caragana (Fabaceae) in China Molecular Evidence for Bidirectional Hybrid Origin and Hippophae rhamnoides ssp. sinensis as the Mainly Maternal Plant of the Diploid Hybrid H.goniocarpa(Elaeagnaceae)