Sagittaria is a genus of ca. 40 species in the aquatic plant family Alismataceae with a nearly global distribution, and a center of diversity in the New World. Two thirds of the known species are native to the Americas, while only a few species are distributed in Africa, Asia and Europe. A previous biogeographic analysis of the genus suggested an African origin for the genus with subsequent dispersal to North America and then to East Asia. Here we expanded the taxon sampling with a focus on the New World taxa and applied species delimitation and biogeographic analyses to revise the knowledge of the phylogeny and evolution of the genus. We obtained largely similar topologies from the chloroplast DNA and nuclear DNA (ITS) data sets. The 74 accessions sampled for our analyses were delimited into 29 species and several cryptic taxa were revealed in widely distributed species. Biogeographic analysis supported basal diversification in South America and subsequent colonization to North America and Asia.

射手座是ca的一个属。水生茜草科的水生植物科中有40种，分布在全球各地，是新世界的多样性中心。三分之二的已知物种是美洲原住民，而只有少数物种分布在非洲，亚洲和欧洲。对该属的先前生物地理分析表明，该属的起源于非洲，随后扩散到北美，然后扩散到东亚。在这里，我们重点关注新大陆分类群扩展了分类群采样，并应用了物种定界和生物地理分析，以修改对属的系统发育和进化的知识。我们从叶绿体DNA和核DNA（ITS）数据集获得了大致相似的拓扑。用于我们分析的74个种质被划分为29种，在广泛分布的种中发现了一些隐性分类群。生物地理学分析支持了南美的基础多样化以及随后向北美和亚洲的殖民化。