白刺科由4个变异较大的属组成，在被子植物系统中具有多变和复杂的系统位置，并具有洲际间断分布格局。基于我们对白刺属的系统发育和生物地理研究，本项目拟对白刺科齐全的种类进行7个序列ITS、rbcL、psbB-psbH、trnL-trnF、rpS16、psbA-trnH 和 rpS16-trnK 测序，建立白刺科多基因的系统发育树，深入研究系统和分类问题；重建白刺科的时空进化历史，主要是作时间维的分子钟测年和空间维的祖先分布区分析，确定白刺科的起源和分化年代，确定祖先分布区，确定主要类群分支节点的分化；结合地质历史事件，特别是大陆板块位移，青藏高原隆升，古地中海退却和中亚干旱化等，对白刺科的演化历史和洲际间断成因作出尽可能合理和可信的解释。这些研究，对被子植物系统，对洲际间断分布格局，对干旱区植物多样性，都有重要的研究意义。

The family Nitrariaceae, including four variable genera, has complicated systematic positions in the angiosperm system historically, and has an international disjuction distribution pattern. Based on our previous phylogenetic and biogeographical research of the genus Nitraria, we want to investigate the phylogeny and biogeography of Nitrariaceae by using a valid reconstructing phylogenetic tree basing on seven sequences ITS, rbcL, psbB-psbH, trnL-trnF, rpS16, psbA-trnH, and rpS16-trnK. Spatiotemporal evolutionary history will be conducted by means of molecular clock and ancestral area reconstruction, so that explore the time and place of origin and divergence of the family. Combining with the geological historical events, especially plate tectonics, Qinghai-Tibetan Pleteau (QTP) uplift, Tethys retreat, and Central Asian aridification, we attemp to explain the reasonable dynamics of evolutionary history and international disjuction of the family. These studies have of significance for the angiosperm systematics, international disjuction distribution pattern, and biodiversity conservation of the arid regions.