Pollen morphology in the genus Coffea (Rubiaceae) and its taxonomic significance

The pollen morphology of 38 representative species and varieties within the genus Coffea L. is described. Eight pollen types, placed in two major groups, have been identified on the basis of the number of colpi, colpus characteristics, exine morphology and pollen size. Differences in pollen structures of the species studied do not correspond to present taxonomic groupings, but support a current proposal to place some of the species in the genus Paracoffea Leroy. Among the four sections in the genus, the section Eucoffea contains a high degree of pollen polymorphism.     

Pollen Morphology of the Genus Malus and Its Taxonomic and Evolutionary Significance

The pollen morphology of 26 species and 5 hybrids of the genus Malus was investigated with aid of SEM. It is found that the pollen morphology of Malus is rather similar in shape, size, position and number of aperture and exine sculpture. The characters of polle morphology of sections and series are as follows: Sect. Malus Ser. Baccatae: Striae regular, parallel to colpi, and conjunct at pole; Ser. Pumilae: the same as in Ser. Baccatae, but more or less curved near pole. Sect. Docyniopes: Striae regular and parallel to colpi, but bent near pole. Sect. Chloromeles: Striae irregular, dense and interlock. Sect. Sorbormalus: Striae irregular, sparse and not interlock. Ser. Sieboldiance: pollen grains prolate, with perforation among striae, colpi narrow; Ser. Kansuenses: Pollen grains spheroidal, colpi wide in the middle but narrow at both ends, striae relatively dense and regular, mostly dichotomous, perforation present; Ser. Yunnanenses; Pollen grain spheroidae, colpi wide in the middle but narrow at both ends, striae obviously irregular, less dichotomous, perforation absent. The major evolutionary trend of exine sculpture of pollen may be from densely thin-striate to sparsely striate with perforation. Characters of the exine sculpture of hybrids can be used to recognize the rela-tionship between the parental species.     

Pollen Morphology and Its Taxonomic Significance of Caragana Fabr. (Fabaceae) from China

Pollen grains of thirty one species and two varieties of the genus Caragana Fabr. were observed under LM and SEM.The results revealed that the pollen exine ornamentation of the species examined could be divided into two types: perforate and reticulate.The later type consists of two subtypes according to lumina size and muri width. In the first subtype the lumina is round with d iameter equal to muri width,and the exine is perforate in two polar areas,while in the second subtype lumina is irregular or polygonal,with diameter sm aller than muri width.The pollen volume was divided into four types.The genus Caragana is a natural group which was indicated by the general resemblance of pollen morphology. In this genus the pollen morphological classification was not in concordance with the arrangement of the sections and series except Ser.Pygmeae and some species. The pollen variation at infraspecific level was obvious,especially the species distributed in Qinghai Xizang Plateau, such as C.jubata, C.bicolor and C. erinacea . The evolutionary trend of pollen morphology is from perforate to reticulate, which is congruous with the evolution from the pinnate leaf group to the almate leaf group in the genus.     

国产省藤属植物的花粉形态学

对国产棕榈科省藤属(Calamius L.)15种植物的花粉进行了光学和扫描电镜观察,其中12种为首次报道。省藤属的花粉均为两沟型花粉,外壁覆盖层多为网状纹饰(大喙省藤C．macrorrhynchus)或具穿孔(华南省藤C.rhabdocladus)。首次发现省藤属花粉的外壁纹饰存在穿孔和外壁疣状突起的类型(阔叶鸡藤C.pulchellus)以及皱波状突起的类型(长鞭省藤C.flagellum)。花粉的大小、形状、外壁纹饰、外壁是否有突起,外壁厚度和网状纹饰网眼的大小,对于省藤属的种级分类有较大的意义。     

锦鸡儿属花粉形态及其分类意义

在光学显微镜和扫锚电镜下对锦鸡儿属31种2变种植物花粉形态进行了观察。根据外壁表面纹饰,可分：类型I,表面具小穿孔;类型II, 具网状纹饰。 在类型II中据网眼大小和网脊宽度特征又分为两个亚类型。 根据花粉体积大小,可分4个类型。本属植物花粉形态较为一致,表明是一个自然类群。组、 系的花粉形态特征与一般形态变异不一定相对应,即形态上有明显区别的种类,在花粉形态上未必有很大区别,仅一些种类及矮锦鸡儿系 Ser. Pygmaeae的花粉形态相近。 本属花粉形态在种下等级的变异, 特别是青藏高原分布的种类的变异较为明显,例如 C.bicolor,C. jubata,C. erinacea 与各自的近缘种类。花粉形态为分类处理提供了参考。本属植物花粉形态是从表面具小穿孔向具网状纹饰演化,对应于羽状叶类群向掌状叶类群演化。     

中国特有属牛筋条属的花粉形态与其系统位置

从发育的角度研究了中国特有单种属DichotomanthesKurz及与其系统学研究有关的外类群Prinsepiautilis的花粉形态 ,扫描电镜观察显示Dichotomanthes花粉粒自脱离四分体胼胝质膜开始至成熟二核花粉粒不同发育时期 ,花粉形态和外壁纹饰未见变化 ,仅花粉体积随成熟度增加而有所增大。而Prinsepiautilis ,其花粉粒刚脱离四分体时形状和成熟花粉明显不同 ,成熟花粉极面观为三裂圆形 ,赤道面观为圆形 ,外壁具清晰的平行条纹 ,但幼嫩花粉粒的形状很特别 ,极面观为深三裂圆形 ,赤道面观亦见花粉在两条沟之间下陷而沟部外突 ,明显为角萌发孔花粉 ,且花粉体积较成熟者小 ,而外壁纹饰同成熟者相比无根本性差异。前述两种植物花粉在不同成熟期体积有明显差异 ,而外壁纹饰在不同成熟期不存在质的变化并相对稳定 ,说明花粉外壁纹饰这一性状在蔷薇科中具有较为重要的分类学意义。DichotomanthesKurz具典型Rosaceae花粉的三孔沟结构 ,外壁具条纹 -穴状纹饰。将其孢粉学特征同Rosaceae 4个亚科有关类群的同类资料相比较 ,并结合其它形态解剖与细胞学等研究结果 ,支持将Dichotoman thes置入Maloideae下而不赞同将其另立亚科或置于Prunoideae之下。此外 ,由于Prinsepiautilis的花粉在其发育初期具角萌发孔花粉 ,与Cunoniacea     

Taxonomy of the Genus Oreocharis (Gesneriaceae)

The genus Oreocharis as circumscribed here consists of 27 species including 5 varieties, of which 5 species and 4 varieties are described as new in the present paper. In the work analysed were the external morphology and geographic distribution and examined under SEM were pollen exine of 22 species and seed coat of 16 species. As a result, three types of the corolla, two types of the anther, three types of the pollen exine and three types of the seed coat are distinguished here in the paper. It is discovered that the corolla in the genus is relatively stable, though diverse, and highly correlated with the characters of pollen grains and seeds. The corolla clearly bilabiate but constricted at the throat, occurring in O. auricula, O. cordatula, O. aurantiaca, etc., for an example, is correlated with smooth, reticulate pollen exine and partial tectum and the reticulate and smooth seed coat. For this reason the subdivision of the genus in the paper is mainly based on the characters of the corolla, but combined with those of the anther, pollen and seed coat. The genus is divided into four sections in the present classification. Dasydesmus Craib, based on a single species. O. bodinieri, is reduced here, and the reasons are given. The genus is distributed mainly in the subtropics, and less frequently in the tropics, of China south of 32.5°N and east of 98.5°E, with only two species beyond the border, O. hirsuta in Thailand (only a single locality in Chiengmai) and O. aurea also found in north Vietnam (see Fig. 1, Table 3). Sect. 1. Stomactin (Clarke) Fritsch. Corolla urceolate-tubular, constricted at the throat, with limb distinctly bilabiate; anthers broad-oblong; seed coat reticulate, smooth, rarely minutely tuberculate; pollen exine fine-reticulate, tectum partial and smooth, luminae slightly unequal in size. Sect. 2. Orthanthera K. Y. Pan Corolla campanulate or campanulate-tubular; anthers broad-oblong; seed coat reticulate, muri smooth, rarely spiny-processed; pollen exine fine-reticulate, with partial and smooth tectum and luminae slightly unequal in size, rarely exine insular and fine-tuberculate, tectum perforate. Setc. 3. Oreocharis Corolla thin-tubular; anthers broad-oblong; seed coat densely spinyprocessed, rarely fine-tuberculate; pollen exine insular, densely spiny-processed, rarely finereticulate and smooth, luminae unequal in size. Sect. 4. Platyanthera K. Y. Pan Corolla campanulate; anthers hippocrepiform; seed coat densely spiny-processed; pollen exine fine-reticulate, tectum perforate, luminae small, nearly equal in size. In the section Stomactin, although the constriction of corolla at its throat is a specialized character, the characters of seed coat, pollen grains and anthers are apparently primitive. Therefore it may be said at least that more primitive characters are preserved in the section. In the section Oreocharis, on the contrary, the characters of corolla, seed coat and pollen exine are all advanced. And in the section Platyanthera, the seed coat, pollen (with perforate tectum) and anthers have developed rather specialized characters.     

Pollen morphology of the tribe Cynoglosseae of Boraginoideae (Boraginaceae) in China

Pollen morphology of 16 Chinese species representing 7 genera in the tribe Cynoglosseae of Boraginoideae(Boraginaceae) was examined under LM and SEM, and 5 species under TEM. Pollen grains are cocoon-shaped, rarely subprolate, prolate or ovoid, very small, 7～ 15.7μm× 3.5 ~ 13.9 μm in size, P/E = 1.6～2.02; 3-colporate apertures alternate with 3-pseudocolpi, with equatorial endocingulus except those in Bothriospermum; exine surface is usually smooth, with or without perforations in two poles, rarely with tuberculate ornamentation; exine is rather thin and includes ectexine and endexine, while ectexine consists of imperforate tectum, columellae and foot-layer. The tribe Cynoglosseae has many common characters of pollen grains, but there are some differences among genera. A key to the genera is given based on pollen morphology. Bothriospermum, without endocingulus, may be a primitive genus in this tribe, and its pollen morphology is more similar to that of Eritrichieae than to Cynoglosseae, thus it seems more reasonable to put it into Eritrichieae. Solenanthus may be the most advanced genus in the tribe Cynoglosseae for its pollen grains of sub-isopolar and ovoid shape.     

New insights into the pollen morphology of the genus Mutisia (Asteraceae, Mutisieae)

The pollen morphology from 67 collections representing 52 species of Mutisia was analyzed by means of light, scanning electron and transmission electron microscopy. Pollen of Mutisia is comparable to that of the more widespread type found in Mutisiinae. The pollen grains of the genus are characterized by the spheroidal-subprolate to prolate shape, large size, tricolporate aperture, with mesoaperture, exine Mutisia type, with sculpturing microechinate to rugulate or microechinate-rugulate. This basic pollen type is very variable in size, endoaperture shape, and exine thickness of the pollen grains. A new type of arrangement of columellae was observed in pollen of Mutisia section Mutisia (e.g., M. stuebelli, M. microphylla, and M. sodiroi). It is suggested that it might have harmomegathic significance. The pollen morphology and polymorphism are discussed with regard to functional mechanisms and possible evolutionary significance.     

Die pollenmorphologie der afrikanischen buxus- und notobuxus-arten (buxaceae) und ihre systematische bedeutung

Pollen grains of 8 African species of Buxus and Notobuxus were examined by light and scanning electron microscopy. Three pollen types are recognized based on the exine sculpture and the evolutionary trends of the pollen characters are discussed. Pollen morphology shows the existence of three major systematic groups. These results support the previous classification of an African section Probuxus with two subsections and speak in favor of the generic rank of the Notobuxus species. Together with anatomical and taxonomical data pollen morphology and its evolutionary trends lend support to the suggestions that the centre of origin of the genus Buxus might have been in Africa, while secondary centres of evolution have developed in the neotropical and Eastasian region.     

槭树科花粉形态及其系统学意义

报道了槭树科(Aceraceae)槭属21组33种和金钱槭属2种植物的花粉形态。本科花粉近球形至长球形,极面观为三裂圆形。从花粉萌发孔类型看,金钱槭属Dipteronia具三孔沟,槭属（Acer)除4组具三孔沟外,其余均为三沟。从花粉外壁纹饰看,金钱槭属2个种和槭属的大多数种为条纹状,罕为细条纹－拟网状和皱波状。通过花粉形态分析,并结合其它方向的证据,我们认为：（1）Sect.Palmata,Sect.Spicata和Sect.Microcarpa可能是槭属中与金钱槭属关系最密切的类群;（2）A.distalum和A.nipponicum代表了近缘的两个单种组;（3）A.pseudoplatanus不同于Sect.Acer的其它4个种而与A.saccharum可能存在更为密切的关系;（4）Sect.Carpinifolia(细条纹－拟网状外壁纹饰）和Sect.Negundo(皱波状外壁纹饰）则可能代表了槭属中最特化的类群;（5）按槭树科花粉三孔沟到三沟的演化规律,Dipteronia较Acer原始。     

Pollen morphology of the tribe Rhinantheae (Orobanchaceae) and its systematic significances

Pollen morphology of 36 species representing 14 genera within the tribe Rhinantheae in the family Orobanchaceae was studied and illustrated with light microscopy (LM) and scanning electron microscopy (SEM). Five major pollen types were recognized on the basis of exine ornamentation. Within these major types, minor types (subtypes) were distinguished based on exine surface pattern, size, shape, amb form, colpi and colpus membrane. These types and subtypes are as follows: type I. retipilate: subtype Ia. regular retipilate: (1) pollen size < 27 μm, (2) pollen size > 27 μm, subtype Ib. irregular retipilate; type II. verrucate: subtype IIa. macro-verrucate, subtype IIb. verrucate, subtype IIc. sparse verrucate; type III. retirugulate; type IV. granulate; type V. micro-reticulate. A key to pollen morphology of genera studied within the Rhinantheae was made based on pollen morphology from our study and earlier work. Combining with other sources of information on the Rhinantheae, the systematic relationships of this tribe are discussed. Rhinantheae pollen displays considerable variation between genera and species, with taxonomically significant characters at genus and species level. Palynological characteristics provide evidence for interpreting the conflicting views concerning the “Pterygiella Complex”. The evolutionary trend in exine sculpture of Rhinantheae could be proposed, namely that retipilate sculpturing which is the most widespread type is more primitive than the other types (such as foveolate, granulate, regulate, reticulate, retirugulate and verrucate). The pollen data in present study and the view of Hong (1986), as well as the molecular data from Bennett and Mathews (2006) indicated that Asia and related regions were likely to the origin centre of the tribe Rhinantheae.     

青藏高原东缘28种风毛菊属植物花粉形态研究

通过扫描电镜对青藏高原高寒草甸风毛菊属28种多年生草本植物的花粉进行了形态观察和比较,结果显示,该属植物花粉形态较为一致。花粉近球形或长球形,极面观三裂圆形,三孔沟,外壁表面具刺状突起。刺间纹饰可分为4种类型:穴状、颗粒状、网状—颗粒状和网状。花粉形态没有大的差异,但刺间表面纹饰、萌发沟的宽窄、刺的大小、分布密度和花粉大小在种间存在差异,可作为种的分类依据。花粉特征聚类分析结果表明,此28种风毛菊属植物花粉大致划分为明显的5个类群,所包含的种分别隶属于风毛菊属的四亚属:雪兔子亚属、雪莲亚属、附片亚属和风毛菊亚属。     

Pollen Morphology of the Genus Nomocharis and Its Delimitation with Lilium

In this work examined were pollen grains of 6 species of Nomocharis and 4 species of Lilium, all under LM and SEM, but Nomocharis saluenensis Balf. f. under TEM. The pollen grains are monocolpate (distal) in Nomocharis, monocolpate or 2-3-porate in the species of Lilium examined. Two types of pollen grains in Nomocharis are recognized based upon the exine stratification and sculpture. The pollen characters and gross morphology, and their evolutionary trends in both Nomocharis and Lilium are discussed. Our conclusions are as follows: 1. Lilium henrici Franch. 、L. souliei (Franch.) Sealy 、L. lophophorum (Bur. et Franch.) Franch. and L. nanum Klotz. et Garcke differ from Nomocharis in the aperture and sculpturing elements. Their pollen morphology supports their being placed in Lilium. 2. The pollen grains of both Lilium lophophorum (Bur. et Franch.) Franch. and L. nanum aggregate are monocolpate or 2-3-porate, which shows an evolutionary trend of aperture from monocolpate to porate, as suggested by Walker and others [Walker et al., (1975), and Chanda (1979)]. 3. In Balfour’s (1918) classification system of Nomocharis, N. pardanthina Franch. and N. meleagrina Franch. belong to Sect. Nomocharis, while N. forrestii and N. biluoensis are placed in Sect. Ecristata, but their pollen grains are all reticulate. They refer to type I (see Table 2). Thus, it does not seem reasonable placing in a single section, Sect. Ecristata, N. forrestii and N. biluoensis with the reticulate exine and N. saluenensis and N. aperta with the two-row-ritipilate exine. 4. Nomocharis saluenensis Balf. f. differs from Lilium in the exine sculpture, which seems to support placing it in Nomocharis. 5. Muri of N. forrestii Balf f. and N. biluoensis s.y. Liang show a tendency of connecting each other by heads of pili, and these two species are intergraded with the other species of the type I with respect to gross morphorlogical characters. It is thus considered that the reticulate pollen grains in Nomocharis is derived from ritipilate ones. This opinion is also held by Nair (1965). 6. Nomocharis differs from Lilium in the exine ornamentation, but some species of Nomocharis are very similar to Lilium in the gross morphology. It shows the close affinity between Nomocharis and Lilium.     

Pollen morphology and infra-generic evolutionary relationships in some Chinese species of Pedicularis (Scrophulariaceae)

 The pollen grains of 32 Chinese species of Pedicularis representing 13 groups within the genus were investigated using light microscopy and scanning electron microscopy. The genus is eurypalynous, the apertures may be tricolpate, trisyncolpate, or bisyncolpate and five types of surface ornamentation (microscabrate, microrugulate, retipilate, microreticulate and microfoveolate) were observed. Comparison of the different aperture types using light microscopy allows three pollen types to be distinguished. Examination of exine ornamentation with scanning electron microscopy enabled each pollen type to be divided into two or three sub-types (giving a total of seven sub-types). Pollen morphology within the genus is discussed in relation to infrageneric relationships, evolutionary and pollination biology. There is little correlation with the existing infrageneric taxonomy (some taxonomic groups have more than one pollen type, while the same pollen type may be found in several different species-groups), but greater correlation with the corolla morphology. Received January 10, 2002; accepted March 5, 2002 Published online: March 10, 2003     

The Restoration of the Genus Cyclocodon ( Campanulaceae) and Its Evidence from Pollen and Seed-coat

The genus Cyclocodon Griff. was reduced by C. B. Clarke in 1881 into a section of the genus Campanumoea. Our LM and SEM observations on pollen morphology show that the pollen of all the three species in the former is 3-colporate with the exine sparsely high-spinulose, whereas that of the two species in the latter is 5～8-colpate with the exine relatively densely short-spinulose. SEM observations on seed-coat indicate that the primary ornamentation of the seed-coat of the two species in Campanumoea (s. str. ) is characterized by regular and polygonal areoles which are much larger than the radial walls in diameter and by the bead-like secondary ornamentation on the radial walls, while that of the three species in Cyclocodon is characterized by irregular-shaped areoles which are nearly equal to the radial walls in diameter and by the rope-like secondary ornamentation on the radial walls. Thus, the pollen morphology is closely correlated with the seed-coat morphology. Taking the characteristics of pollen, seed-coat and gross morphology into consideration, the genus Cyclocodon is restored, separate from Campanumoea (s. str. ). One new combination, Cyclocodon celebicus (B1.)Hong, is made in the present paper. The genus Cyclocodon is con-sidered closely related to Platycodon rather than to Campanumoa.     

Pollen morphology of Chinese Curcuma L. and Boesenbergia Kuntz (Zingiberaceae): Taxonomic implications

In order to find new non-molecular evidence to support the phylogenetic and taxonomic position, pollen grains of 20 populations of 16 species of Chinese Curcuma L. and Boesenbergia Kuntz (Zingiberaceae) were investigated under SEM and TEM. The pollen grains are spherical and ovoid, nonaperturate. The pollen wall is composed of a very thin exine and a thick intine. The exine is psilate or echinate. The intine consists of two layers, i.e., a thick, channeled layer (exintine) and an inner homogenous layer (endintine). The results reveal morphological congruence between the pollen grains of species of Curcuma, which according to DNA sequence data appears to be a polyphyletic genus. However the uniform pollen morphology in Curcuma provides no evidence to divide this genus into separate taxonomic entities. Our results on pollen morphology also do not provide any additional evidence to either unite or segregate Boesenbergia albomaculata and Curcumorpha longiflora in the same genus and demonstrate that more taxonomic data on the genus Boesenbergia and its relatives are needed before a final decision can be made.     

Pollen morphology of some species of Vernonia s. l. (Vernonieae,Asteraceae) from Argentina and Paraguay

Pollen morphology is widely used in taxonomic treatments of tribe Vernonieae, and differences in exine structure and aperture form have been described for many species within the genera comprising the tribe. However, in recent years a number of new species have been described and, in the present paper, we describe in detail the pollen of 24 species of the tribe which are either endemic or uncommon to certain regions of Argentina or of Paraguay. The pollen of these species are radially symmetrical and more or less spheroidal, 3‐colporate or, in one species, 3‐porate; the exine may be tectate or semitectate and microperforate, with echinate lophae or, in the 3‐porate example, psilate lophae. Using a range of characteristics related to size, shape, wall thickness, apertures and tectum surface morphology, five of the six pollen types previously described for tribe Vernonieae, and a subtype, are recognized. Our results support the usefulness of pollen morphology in helping to determine the taxonomic position of species within tribe Vernonieae.     

A palynological study of the genus Mentha L. (Lamiaceae)

The pollen morphology and exine structure of 10 Mentha L . species were investigated using light microscopy and scanning electron microscopy. The pollen grains of all 11 species were hexazonocolpate with granular membranes and a circular amb, varying in shape from prolate-spheroidal to suboblate. Different colpus shapes were recognized in M . ×  dumetorum . The exine was bireticulate in section Pulegium , and reticulate in section Menthae . A correlation was found between pollen size and chromosome number. The results indicate that the pollen characters of the genus Mentha are valuable for taxonomic applications and may be useful for classification.  © 2008 Uludag University. Journal compilation © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 157 , 141–154.     

Pollen morphology in the genus Veronica L. (Plantaginaceae) and its systematic significance

Pollen grains of 30, mainly annual, species from 134 populations of the genus Veronica (Plantaginaceae, formerly Scrophulariaceae) from the Mediterranean Region, have been studied with light and scanning electron microscopy. Three pollen types are defined based on pollen size and exine surface sculpture. In some cases within the study group pollen size can be useful in species determination. Hypothetical relationships of pollen grain size and aperture number with ploidy level, style length and corolla diameter are discussed. The ornamentation of the exine in Veronica, although generally a conservative character within the genus, gives some additional support to the most recent infrageneric classification of Veronica.