勿忘草属隶属于紫草科（Boraginaceae）勿忘草族（Myosotideae），全世界约有80~100种，在广义分布范围内，有2个分布中心：一是西欧的地中海地区，大约60个物种；二是新西兰地区，大约35个物种。中国及泛喜马拉雅地区勿忘草属的研究亦很薄弱，在名实考证、物种划分方面仍存有问题。同时勿忘草属与近缘属的系统发育关系一直存有争议，因此，有必要对勿忘草属开展系统的研究，解决分类学问题，以期完成《泛喜马拉雅植物志》的编写，并为广义勿忘草属的研究提供部分资料。

本次研究在查阅和考证相关文献和各国植物志书的基础上，对国内外20个标本馆近2000份实体和数字化的标本进行仔细的观察研究，并对有疑问的类群进行野外考察与标本采集，分别在新疆、内蒙古、吉林和云南四个地方共采集到4种2变种，17个居群，158份标本。对中国及泛喜马拉雅地区内勿忘草属植物的形态学性状进行了比较研究和分析，以寻找重要的分类学性状，结合叶表皮毛、花萼和小坚果形态等比较形态学证据对勿忘草属进行分类研究和修订；同时，基于核基因ITS片段开展分子系统学研究，探讨勿忘草属和近缘属的系统关系及中国勿忘草属所处的系统位置。主要的研究结论如下：

1. 通过对本属5种1变种植物叶表皮毛形态研究，认为勿忘草属植物表皮毛有三种类型：具有基盘的等长的开展的短糙毛；无基盘的长柔毛；开展的短糙毛和短柔毛混生。观察发现，毛被类型这一性状在同一物种的不同居群中很稳定。前人研究所利用的叶表皮毛类型这一性状可于作物种划分，而前人所指出的毛被的方向则不具有分类价值。

2. 通过对本属6种2变种的26个居群的花萼形态学研究，认为前人研究所指出的花萼开裂的程度（花萼5深裂、5中裂，5浅裂）这一性状对物种划分具有重要意义。同时，观察到花萼长度和花梗长度的关系这一性状亦有重要的分类价值，可分为两类：一类是花萼长度 ≥花梗长度，有4种；另一类是花萼长度 <花梗长度，包括2物种2变种。除此之外，认为前人所指出的花萼的毛被形态这一性状在本研究区域内分类价值较小，可作为物种划分的辅助性状。

3. 勿忘草属果实为两面体形或双凸透镜形，分背腹两面，腹面有龙骨状突起，周围有边，腹面基部有雌蕊基，有或无附属物。本属小坚果的长度范围是1.1~2.4 mm,宽度是0.6~1.7 mm，依据小坚果的大小可区分部分属下物种。对本属6种1亚种2变种小坚果形态拍摄观察，认为前人所指出的小坚果的形态这一性状对于物种划分具有重要的意义，但对小坚果周围边的宽度进行观察统计，发现物种之间区分不大，认为不具备分类学意义。

4. 基于核基因用最大似然法，最大简约法和贝叶斯法构建了中国勿忘草属的系统发育树，增加了中国及泛喜马拉雅地区的样本数量，并未使其单系性改变，与前人所研究的勿忘草属为单系类群结果一致,且与假滨紫草属亲缘关系最近；同时，确定了中国勿忘草属的系统学位置，属于广义勿忘草属属下的sect. Myosotis。

5. 完成了对中国及泛喜马拉雅地区勿忘草属的分类修订，确认该地区共有勿忘草属12种2亚种2变种，其中中国8种2变种，泛喜马拉雅地区8种2亚种1变种。确定中国及泛喜马拉雅地区假滨紫草属7种。核实细根勿忘草（M. krylovii Serg.）存在于中国且为广布种，除新疆以外，该种还分布在吉林、四川、云南等地，该种不仅分布范围广而且形态特征很稳定,是一个“好种”。首次发现并证实M. laxa Lehm.复合体在中国存在，并对复合体进行了性状分析，确定花序基部花梗的长度这一性状可对复合体进行种下分类等级划分，支持前人的观点，将湿地勿忘草（M. caespitosa Schultz）和M. baltica Sam.处理为M. laxa Lehm.的变种。同时，认为承德勿忘草果期花梗的长度可达2.2 cm、小坚果似正三角形等特征描述符合M. laxa Lehm.，故认为应将承德勿忘草（M. bothriospermoides Kitag.）进行归并，处理为M. laxa Lehm.的异名。

Myosotis L. belongs to Boraginaceae (Myosotideae) which consists about 80–100 species in the world. There are two distribution centers: one in the Mediterranean region of Western Europe, about 60 species, the other is New Zealand, about 35 species. Studies of Myosotis L. in China and the Pan-Himalayan region are even weaker. There are still many problems in the nomenclature and species identificaton. At the same time, the phylogenetic relationship between Myosotis L. and Related genera have been controversial. Therefore, it is necessary to carry out a systematic study of Myosotis L. to complete the compilation of Flora of Pan-Himalayan and provide some data for the study of Myosotis L.s.l.

Based on the literature and botanical books of various countries, this study carefully observed and studied nearly 2,000 physical and digital specimens from 20 domestic and foreign herbariums. The taxa were field-examined and collected. Four species, two varieties, 17 populations, and 158 specimens were collected in four places in Xinjiang, Inner Mongolia, Jilin, and Yunnan. The preliminary analysis of the traits of the genus in the scope of the study, looking for favorable traits, combined with comparative morphological evidence such as leaf epidermal hairs, calyx and nutlet morphology to classify and modify the genus; at the same time, using the molecular systematics nuclear gene ITS to clarify Phylogenetic relationship between Myosotis L. and its relatives and the phylogenetic position of the genus in China. In summary, the main conclusions are as follows:

1. Based on the study of leaf epidermal hair morphology of 5 species and 1 variety of this genus, it is believed that there are three types of epidermal hairs of Myosotis L.: equal length developing short bristle with basal plate; long bristle without basal plate; mixed type of developing short bristle and short bristle. It was found that the trait of epidermal hair type is stable in different populations of the same species. The trait of the leaf epidermal hair type used by previous research institutes can be used for species classification, while the direction of the hair coat pointed out by the predecessors has no classification value.

2. Through the analysis of 26 taxa of this genus (6 species and 2 varieties) morphological study of the calyx, it is considered that the degree of calyx dehiscence (calyx 5 deep dehiscence, calyx 5 middle dehiscence, calyx 5 shallow dehiscence) indicated by previous studies is of great significance for species division. At the same time, it has been observed that the relationship between calyx length and pedicel length, which has not been pointed out by predecessors and can be divided into two categories: one is that calyx length ≥ pedicel length, there are four species; the other is that calyx length < pedicel length, including two species and two varieties. In addition, it is considered that the coat morphology of calyx, which has been pointed out by predecessors, is of little taxonomic value in this study area and can be used as an auxiliary character of species division.            

3. The fruits of Myosotis L. are dihedral or lenticular, divided into two sides of the dorsal and ventral sides, with keel-like protrusions on the ventral surface, with edges around, and a pistil base at the base of the ventral surface, with or without appendages. The length range of the nutlet is 1.1–2.4 mm and the width are 0.6–1.7 mm. Some species can be distinguished according to the size of the small nuts. The morphology of the small nuts of 6 species, 1 subspecies and 2 varieties of this genus was photographed and observed. The morphology of the small nutlets morphology pointed out by the predecessors is of great significance for the classification of species, but the width of the surrounding edges of the small nutlets is observed and statistically found. There is not much difference between them and it is considered to have no taxonomic significance.

4. Molecular systematics research: Based on nuclear genes, ML, MP, and Bayesian methods were used to construct China's phylogenetic tree of Myosotis, which increased the number of samples in China and the Pan-Himalayan region and did not change its monophylicity, which is consistent with the results of previous studies. It is also closely related to the genus Decalepidanthus. Meanwhile, the systematic position of the genus Myosotis in China is determined, which belongs to sect. Myosotis.

5. The classification of Myosotis in China and the Pan-Himalayan region has been revised, and it has been confirmed that there are 12 species, 42 subspecies and 2 varieties of Myosotis in this region, including 8 species and 2 varieties in China and 8 species, 2 subspecies and 1 varieties in Pan-Himalayan region. Identification of 7 species of Decalepidanthus in China and the Pan-Himalayas. It was verified that the species M. krylovii Serg. exists in China and is widely distributed. Besides Xinjiang, this species is also distributed in Jilin, Sichuan, Yunnan and other places. This species is not only widely distributed but also has stable morphological characteristics, so it is a "good species". It is the first time to find and confirm the existence of M. laxa complex in China, and to analyze the characteristics of the complex. To determine the length of the longest peduncle of inflorescence can be used to classify the species under the complex, which supports the previous view. M. caesarpitosa Schultz. and M. baltica Sam. are used as the variant treatment of M. laxa Lehm. At the same time, it was considered that the length of the pedicel in the fruit stage of M. bothriospermoides Kitag. could reach 2.2 cm, and the nutlet like triangle was consistent with M. laxa Lehm., thus, it is believed that M. bothriospermoides Kitag. should be merged into a synonym of M. laxa Lehm.