蔷薇科水榆属（Micromeles）植物约33种（不含变种），分布在东亚、东南亚部分地区，中国约有28种。虽长期放置在广义花楸属下，由于形态上还与梨属、石楠属相似，共发表产生相关物种名称达130个。但不同植物分类学家认为Micromeles所代表的分类等级、物种范围有所不同。基于少数样品的分子系统学研究结果仍未彻底解决水榆属的单系性和系统位置。同时水榆属所包括的物种范围需要重新界定，属内部分物种需重新划分。与之相应的整个属的分类等级、名称变化亟需处理。本申请项目将从原始描述、分类处理文献出发，通过野外调查、采集与测量重要馆藏标本，获得关键形态学数据。同时利用前期已有的工作基础，在全面取样的基础上，重建基于苹果族（Maleae）背景下的水榆属核基因与叶绿体基组的分子系统发生关系。力求解决水榆属在系统发生位置、物种划分和分类修订上的问题。为蔷薇科的系统发生、分类及物种多样性提供新的证据。

There are about 33 species (excluding varieties) of Micromeles (Rosaceae) in the world, distributed in East Asia and parts of Southeast Asia, of which 28 species are found in China. The morphological characteristics of Micromeles plants are similar to genera Pyrus and Photinia. Although it has been placed under the general genus Sorbus s.l. for a long time, a total of 130 related species have been published. Opinions related to the classification of Micromeles taxa and species ranges largely differ among plant taxonomists with there are remaining a lack of consensus. Based on the molecular phylogenies, the monophyletic and systematic position of Micromeles has not completely solved with a few samples. At the same time, the range of species included in the genus needs to be redefined, and some species within the genus need to be re-established. The classification and name change of the entire genus corresponding to it need be dealt with. This project will commence with an in-depth taxonomic reappraisal of Micromeles focused on the species names published under this genus. Key morphological data will be obtained through field surveys, collections, and measurements of collections worldwide. Based on previous work, the molecular phylogenetic relationship of Micromeles with nuclear gene and chloroplast genomes under the Maleae background will reconstruct. We will resolve the phylogenetic position of Micromeles taxa and settle the chaotic and conflicting in species delimitation and taxonomic revision. This program will provide additional evidence for the phylogeny, classification and species diversity of Rosaceae.