广义鱼黄草属（Merremia Dennst. ex Endl. s. l.）隶属于旋花科（Convolvulaceae），旋花亚科（Convolvuloideae），鱼黄草族（Merremieae D. F. Austin），全世界约129种，主要分布于非洲、亚洲、澳大利亚、北美和南美的热带地区。Staples（2017）根据Simoes（2015）基于trnL-trnF、rps16、matK、ITS序列构建的系统发育树，并结合Austin（1980）的研究结果，将广义鱼黄草属划分为5个属：狭义鱼黄草属（Merremia Dennst. ex Endl. s. s.）、茉栾藤属（Camonea Raf.）、金钟藤属（Decalobanthus Ooststr.）、萼龙藤属（Distimake Raf.）和地旋花属（Xenostegia D. F. Austin & Staples）。目前，北美及东亚国家关于本类群的植物志都已编写完成，一些涉及广义鱼黄草属的实验分类学和分子系统学的研究也逐步开展，但由于部分中国特有种的馆藏标本数量少，野外居群调查不足，在名实问题、物种划分和属下分类系统上仍有诸多问题有待解决，对于能否根据花粉形态等重要形态特征建立狭义的鱼黄草属，仍存在一些争议。因此，对中国区域内广义鱼黄草属植物进行全面系统的研究，一方面为世界狭义鱼黄草属和近缘属的修订提供资料，另一方面可明确本类群在中国的物种数量和分布格局。

本研究在文献考证的基础上，研究了国内外24个标本馆2000余份标本，采集了狭义鱼黄草属植物11种6变种、茉栾藤属植物1种1亚种、金钟藤属植物2种1变种、萼龙藤属植物4种和地旋花属植物1种，共收集标本材料550余份，观察了116个居群。通过对标本和野外居群的观察研究，对研究范围内狭义鱼黄草属和近缘属植物形态性状的变异幅度及变异规律进行了归纳总结；利用核基因ITS和叶绿体基因trnL-F数据，探讨了中国广义鱼黄草属的系统发育关系；同时结合花、果、叶、花粉等性状对中国狭义鱼黄草属和近缘属进行了全面的分类学研究。本研究的主要结论如下：

1）形态性状分析结果表明：叶形、叶表皮毛、花萼的形状、花冠形态、蒴果类型和种子形态等特征在广义鱼黄草属中具有重要的分类价值，习性、根的类型、茎的分枝情况、叶的大小和毛被、苞片的有无、花序类型等特征在狭义鱼黄草属及近缘属的属下分类中意义不大。

2）增补和修正了3种广义鱼黄草植物的花冠形态性状描述；认为花冠颜色、花冠类型、花丝基部形态以及花冠基部腺体的毛被、花冠是否具明显瓣中带可作为物种识别的重要依据；广义鱼黄草属的花药弯曲开裂方式有3种类型：沿纵向裂开、螺旋扭曲开裂、纵向开裂并先端稍弯曲，是区分狭义鱼黄草属与近缘属的重要形态特征。结合花形态数量特征的主成分分析结果，编制了15种狭义鱼黄草属的花形态分种检索表。

3）广义鱼黄草属种子基本形态为三棱状卵圆形，种子厚度、种子近轴面及远轴面长度、两端是否尖锐、种子表面微形态对种子形状的识别和近缘属的划分具有重要意义。种子的表面微形态可以识别出4种类型：表面多皱，被毛覆盖；表面具明显的褶皱，被颗粒状突起；表面褶皱明显，具蜂窝状状网纹，内有附属物；表面具不明显褶皱，被粗网状纹饰，内无附属物；表面纹饰是否具明显的褶皱可用于区分近缘种。种子大小及表面纹饰特征与物种的地理分布有一定相关性：100~500 m的低海拔热带地区的种子多为小种子具明显褶皱，1500 m以下的高海拔亚热带地区的种子多为大种子具不明显褶皱。

4）广义鱼黄草属的花粉形态分为以下4类：近扁球形、圆球形、近长球形和长球形。花粉的表面纹饰在本类群中较为一致：外壁具分布均匀的颗粒状纹饰，且厚度明显厚于内层。聚类分析和主成分分析结果表明：花粉的萌发孔特征可用于区分狭义鱼黄草属与近缘属，主要有以下5类：3沟、5~6沟、9~12沟、散孔、散沟。研究发现，中国特有种蓝花土瓜的花粉为散孔型，其萌发沟数量是20~25；地旋花属的花粉也为散孔型，但其萌发孔数量≥30，支持地旋花属的独立地位。

5）分子系统学研究结果表明：广义鱼黄草属是并系类群，应划分为鱼黄草属（狭义）、茉栾藤属、金钟藤属、萼龙藤属和地旋花属。支持地旋花属的独立地位，并支持将M. pinnata Hall. f. 并入地旋花属中。确认美花鱼黄草 [M. caloxantha (Diels) Staples & R. C. Fang] 与篱栏网 [M. hederacea (Burm. f.) Hall. f.] 和金花鱼黄草 [M. gemella (Burhaiba. f.) Hall. f.] 的亲缘关系较远，非两种的过渡种。

6）支持将广义鱼黄草属划分为狭义鱼黄草属、茉栾藤属、金钟藤属、萼龙藤属、地旋花属等5个属。确认中国共有鱼黄草属（狭义）植物13种6变种，其中，6种5变种是我国特有种；1种1变种存疑。茉栾藤属植物共1种1亚种；金钟藤属植物共3种1变种；萼龙藤属植物共4种；地旋花属植物共1种。发现1个中国新分布：埃及萼龙藤 [Distimake aegyptius (L.) Simoes & Staples] 分布于广东省深圳市福田区，为外来种。认为铜钟藤 [Decalobanthus bimbim (Gagnep.) Simoes & Staples] 仅分布在云南省东南部，黄毛金钟藤 [D. boisianus var. fulvopilosus (Gagnep.) Simoes & Staples] 仅分布广西西南部的低山区，修正了中国植物志的错误记载。提出2个新异名：将线叶山土瓜 [M. hungaiensis var. linifolia (C. C. Huang) R. C. Fang]处理为山土瓜 [M. hungaiensis (Lingelsh. & Borza) R. C. Fang] 的异名；认为海南山猪菜正确名称为M. dichotoma Ooststr.，M. hainanensis Kiu是M. dichotoma Ooststr. 的同物异名。支持前人对丘陵鱼黄草 [M. thorelii (Gagnep.) Staples] 和长梗山土瓜 [M. poranoides (C. B. Clarke) Hall. f.] 处理。

7）综合宏观形态学、微形态学以及分子系统学的研究结果，支持地旋花属的独立地位，并对本属的形态特征进行补充：茎细长具细棱；近无叶柄，叶基部戟形，有明显的抱茎现象；萼片卵状披针形，顶端渐尖成细长尖头；花冠喉部紫红色；具散孔型花粉（萌发孔≥30）；种子两端稍尖锐。

Merremia Dennst. ex Endl. s. l. (Convolvulaceae: subtrib. Merremieae D. F. Austin) contains ca. 129 species worldwide, mainly distributed in tropical regions of Africa, Asia, Australia, North America and South America. In 2017, Staples according to the phylogenetic tree constructed by Simoes in 2015 based on trnL-trnF、rps16、matK、ITS and its sequences, and the research results of Austin in 1980, the genus of Merremia s. l. is divided into five genera: Merremia Dennst. ex Endl s. s.、Camonea Raf.、Decalobanthus Ooststr.、Distimake Raf. and Xenostegia D. F. Austin & Staples. Although the Flora of many countries and regions have been completed, and some experimental taxonomic and molecular systematics related to Merremia s. l. have been gradually carried out. However, due to the small number of specimens in the collection of some endemic species in China and insufficient field population investigation, there were still many problems in the classification of Merremia s. l. It is still controversial whether Xenostegia D. F. Austin & Staples can be separated from Merremia s. l. mainly according to pollen morphology. Therefore, a comprehensive and systematic study on Merremia s. l. in the study area can not only provide data for the revision of Merremia s. s. and related genera in the world, but also clarify the species number and distribution pattern of this group in China.

Based on examination literature, the author has checked more than 2000 specimens from 24 domestic and abroad herbarium; collected 11 species and 6 varieties of Merremia s. s., 1 species and 1 subspecies of Camonea, 2 species and 1 variety of Decalobanthus, 4 species of Distimake and 1 species of Xenostegia. More than 550 specimens were collected and 116 populations were observed. Through the observation and study of specimens and field populations, the variation range and variation law of morphological characters of Merremia s. s. and related genera were summarized, and the five genera were classified; Based on the data of nuclear gene ITS and chloroplast gene trnL-F, the phylogenetic relationship of Merremia s. l. in China was discussed; At the same time, combined with the taxonomic evidence of external morphology, leaf coat micro morphology, flower morphology, seed morphology and micro morphology, pollen micro morphology and so on, a comprehensive taxonomic study was carried out on the Merremia s. s. and related genera. The main conclusions are as follows:

1. The results of morphological character analysis showed that the characteristics of leaf shape, leaf coat, calyx shape, corolla shape, capsule type and seed shape had important taxonomic value in Merremia s. l., and the characteristics of habit, root type, stem branching, leaf size and indumentum, bracts and inflorescence type had little significance in the Merremia s. s. and its related genera.

2. Supplement and correct morphology characters of flowers of 3 Merremia s.l. species. Corolla color, corolla type, filament base morphology, hair coat of corolla base gland and whether corolla has obvious middle petal band are significant to species identification. It is found that the degree of anther dehiscence and bending is an important feature to distinguish Merremia s.s. from the related genus. There are three types: longitudinal dehiscence, spiral twist dehiscence, longitudinal dehiscence and slightly curved apex. Combined with the results of principal component analysis, a key table of flower morphology of 15 species of Merremia s. s., was put forward.

3. The shape of seeds of Merremia s. l. is usually triangular oval. The thickness of seeds, the length of adaxial and abaxial surfaces of seeds, whether the two ends are sharp or not, and the micro morphology of seed surface are of great significance for the identification of seed shape and the division of related genera. There are four types of seed surface micromorphology: wrinkled and covered with hair; obvious folds and granular protrusions; obviously wrinkled, with honeycomb reticulation and appendages inside; no obvious folds and is decorated with coarse reticular patterns without accessories. Whether the surface decoration has obvious folds can be used to distinguish related species. The seed size and surface decoration characteristics have a certain correlation with the geographical distribution of species: The seeds in low altitude tropical areas areas of 100-500 m are mostly small seeds with obvious folds, while the seeds in high altitude subtropical areas below 1500 m are mostly large seeds with no obvious folds.

4. Pollen shape varies from suboblate, oblate-spheroidal, prolate-spheroidal and subprolate. in Merremia s. l. The surface decoration of pollen is consistent in this group: the outer wall has evenly distributed granular decoration, and the thickness is significantly thicker than the inner layer. The results of cluster analysis and principal component analysis showed that the characteristics of pollen germination pores were the most important characteristics to distinguish the morphology of different kinds of pollen in this genus, mainly including the following five categories: 3 colporate, 5~6 colporate, 9~12 colporate, pantoporae and rugate. It was found that the pollen of M. yunnanensis (Courch. et Gagn.) R. C. Fang was of loose pore type, and the number of germination grooves was 20~25; The pollen of Xenostegia D. F. Austin & Staples. is also of loose pore type, but the number of germination pores is greater than or equal to 30, which still supports the independent status of Xenostegia.

5. Molecular phylogenetic study shows that Merremia s. l. was a syngeneic group, which should be divided into Merremia s.s.、Camonea、Decalobanthus 、Distimake、Xenostegia. It supports the independent status of the genus Xenostegia and the incorporation of M. pinnata Hall. F. into the genus Xenostegia. Confirm M. caloxantha (Diels) staples & R. C. Fang and M. hederacea (Burm. f.) hall f. Hall and M. gemella (Burm. f.) Hall. f. is not a transitional species.

6. It supports that the genus of Merremia s. l. is divided into five genera: Merremia Dennst. ex Endl. s. s.、Camonea Raf.、Decalobanthus Ooststr.、Distimake Raf. and Xenostegia D. F. Austin & Staples. There are 13 species and 6 varieties of Merremia s.s. in China, and one species and one variety is doubtful; Among them, 6 species and 5 varieties are endemic to China. There are 1 species and 1 subspecies of Camonea; There are 3 species and 1 variety of Decalobanthus; There are 4 species of Distimake; There are 1 species of Xenostegia. A new distribution: Distimake aegyptius (L.) Simoes & Staples is distributed in Futian, Shenzhen. Confirm Decalobanthus bimbim (Gagnep.) Simoes & Staples) is only distributed in the southeast of Yunnan Province, and D. boisianus var. fulvopilosus (Gagnep.) Simoes & Staples is only distributed in the low mountainous areas in the southwest of Guangxi, and the records of Flora of China are wrong. At the same time, two new synonyms were proposed: M. hungaiensis var. linifolia (C.C. Huang) R.C. Fang is treated as a synonym of M. hungaiensis (Lingelsh. & borza) R.C. Fang; M. hainanensis Kiu is as the synonym of M. dichotoma Ooststr. It supports the previous treatment and its correct name is M. thorelii (Gagnep.) Staples; It is considered that M. longipedunculata (C. Y. Wu) R. C. Fang is reduced as the synonym of M. poranoides (C.B. Clarke) Hall. f.

7. Based on the research results of macro morphology, micro morphology and molecular systematics, supporting the independent status of the genus Xenostegia D. F. Austin & Staples, and the morphological characteristics of the genus are modified and supplemented in the Flora: The stem is slender and ribbed; It is nearly without petiole, and the leaf base is halberd shaped, with obvious stem holding phenomenon; Sepals ovate lanceolate, apex acuminate into a slender tip; Corolla throat purplish red; Pollen with scattered pore type (germination pore ≥ 30); Seeds slightly sharp at both ends.