Pollen morphology of selected Central European species from subgenera Vignea and Carex (Carex,Cyperaceae) and its relation to taxonomy

This study analysed the taxonomic utility of selected features of pollen grains of 45 Central European species of subgenera Vignea and Carex of the genus Carex. Seven quantitative features were analysed: [length of polar axis (P), length of equatorial axis (E), exine thickness on the pole (Exp), exine thickness on the equator plane (Exe), P/E ratio and the relative thickness of exine (Exp/P and Exe/E ratio)] and outline, shape and exine sculpture. Among the biometrical features, the most important for Carex taxonomy (particularly at the level of subgenus) is the thickness of exine (Exp). Marked differences in the morphological structure of inflorescences at the subgenus level are reflected in the differences of pollen features. Results of our studies clearly show an explicit (and not previously described in the palynological literature) taxonomic division of the genus Carex on the basis of pollen biometrical features into two units corresponding exactly to the subgenera (Vignea and Carex). However, the features of pollen grains analysed did not contribute any essential taxonomic criteria at levels lower than subgenus (e.g. sections). An exception was for C. disticha, where it was observed that the poroid areas occurred in pairs, a new feature for sedges. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 164 , 422–439.     

29个蔷薇属植物的孢粉学研究

采用扫描电镜技术对蔷薇属25个种及4个月季品种的花粉形态进行观察分析,探讨单叶亚属及蔷薇亚属中的芹叶组、合柱组、桂味组、月季组及月季品种之间的亲缘关系。研究表明:(1)所有被测样品的花粉都为具三孔沟的N3P4C5型单粒花粉,形状包括近球形、长球形及超长球形,其中大部分都为极轴较长的超长球形,以小檗叶蔷薇(P/E=2.29)最长。(2)在疏花蔷薇、托木尔蔷薇以及重瓣黄刺玫中发现有花粉二型现象。(3)被测样品外壁纹饰主要包括条纹、孔穴-条纹及近孔网纹3类,条纹类型主要出现在芹叶组中,而孔穴-条纹类型则为蔷薇属植物较普遍的纹饰。(4)聚类分析表明,小檗叶蔷薇与其它种亲缘较远,被测月季品种与月季组关系较近,芹叶组与合柱组关系较近,桂味组中的弯刺蔷薇与其他蔷薇的纹饰有明显区别,被单独分开。     

Morphological studies of pollen grains of the Polish endemic species of the genus <Emphasis Type="Italic">Rubus</Emphasis> (Rosaceae)

The pollen of six taxa of the genus Rubus endemic to Poland (R. capitulatus, R. chaerophylloides, R. ostroviensis, R. posnaniensis, R. seebergensis and R. spribillei)was studied using light and scanning electron microscopy. The study objective was to extend the knowledge of the species pollen morphology and to investigate whether pollen morphology may help to taxonomically distinguish a very rare bramble species. Study material was derived from six natural localities where the species occur in the Wielkopolska region (Poland). Ten quantitative pollen grain features were analysed as well as the following qualitative ones: outline, shape, type of bridge and exine sculpture. Only mature, correctly formed pollen grains (30 per specimen) were measured and 180 pollen grains were examined in total. It was found that R. capitulatus and R. seebergensis had the highest mean values of P, E and Le features. In addition, pollen grains of R. capitulatus were most flattened (mean P/E ratio equals 1.14), while those of R. seebergensis were most elongated (mean P/E ratio equals 1.27). R. spribillei was the only species with striae of similar width as muri, whereas striae in the remaining species were wider. R. chaerophylloides and R. posnaniensis were characterised by specific, similar exine sculpture. Nevertheless, it should be stated that differences between pollen features of the species studied are so small and the variability of these features are so large that it is difficult to clearly identify the species studied. Therefore, pollen grain morphology can serve only as an auxiliary feature for the determination of these species.     

The palynology of the genus Rondeletia L. (Rubiaceae-Cinchonoideae-Rondeletieae)

Pollen of 20 species of Rondeletia, covering three subgenera and seven sections or “species groups” of the genus, was studied using light and scanning microscopy. Rondeletia, characterized by binucleate mature pollen grains like numerous other Rubiaceae, was found to be eurypalynous. The pollen is isopolar and small-sized (average equatorial diameters 11.4–22.8 μm) and 3-colporate (rarely 4-colporate). In equatorial view, the pollen grains are mostly ± spheroidal (rarely suboblate); in polar view (ambitus), they are mainly circular or semiangular (intersemiangular in one species only). Three different exine types are distinguishable: exine with 1) tectum minutely perforate, perforations usually isodiametric, 2) tectum with comparatively large, not isodiametric perforations or 3) coarsely reticulate; supratectal sculpturing elements are lacking; the width of the perforations and lumina is either equal or different at the apo- and mesocolpia; in a few species rod-like luminal processes are present. Palynological features of most of the investigated taxa tend to overlap so that palynology is not very helpful in supporting the subgeneric division of Rondeletia. It was, however, noted that pollen morphology, to some extent, supports the sections of subgen. Arachnothrix. Palynologically, the subgen. Rogiera was found to be heterogeneous in that each of the three investigated species is characterized by a different exine type; one of these, R. strigosa, differs from all other Rondeletia species investigated in having a coarsely reticulate exine. R. odorata (subgen. Rondeletia) differs from all other investigated species in its intersemiangular pollen shape.     

Palynological survey of the subtribe Elephantopinae (Asteraceae, Vernonieae)

Despite the taxonomic value of pollen morphology within the tribe Vernonieae, a detailed study of the pollen of the subtribe Elephantopinae is still lacking. The pollen morphology of ten species, representing three of the four genera of the subtribe, Elephantopus, Pseudoelephantopus and Orthopappus, was studied with LM, SEM, and TEM. The pollen of all the species studied was found to be echinolophate, although the differences in aperture features and both sculpture and exine structure allowed recognizing two pollen types. The species of Elephantopus (except for E. elongatus) and Pseudoelephantopus share the regular or more or less regular ridges pattern, the colporate condition but with the ectoapertures little developed, and the acaveate exine structure. From the sculpture and the apertures, the pollen of Caatinganthus harleyi was found to be similar to that of Elephantopus and Pseudoelephantopus. The pollen morphology of the monotypic Orthopappus, which is shared with that of E. elongatus, was further investigated for the first time. We found that it differs from that of the other species in having an irregular pattern of ridges, colporate condition but with a well-developed ectoapertures, and caveate exine. Additional studies of the exine structure and apertures features, coupled with molecular phylogeny, are needed to understand the evolution of pollen characters and re-evaluate the intergeneric relationships within the tribe.     

杜鹃花属植物花粉形态及其分类学意义

利用扫描电子显微镜对5个亚属20种杜鹃花属植物的花粉形态进行了观察和比较研究,其中大部分(16种)为首次报道。杜鹃花属花粉均为四合花粉,呈正四面体排列。四合体为圆角三角形,连接紧密。单粒花粉为球形或近球形,具三沟孔。在扫描电镜下,除了杜鹃亚属的百合杜鹃、羊踯躅亚属的羊踯躅以及马银花亚属的马银花组具有明显的纹饰特征之外,其它类群的形态特征相互重叠,不足以作为现有亚属的分类依据。花粉粒具不同的外壁纹饰,可为分类研究提供孢粉学方面的证据,但应慎重应用花粉形态对杜鹃花属植物特定种进行分类鉴定。     

Lilium spp. pollen in China (Liliaceae): Taxonomic and Phylogenetic Implications and Pollen Evolution Related to Environmental Conditions

Recent molecular and karyologic studies have significantly modified delimitation of Lilium. However, despite the importance of pollen evolution in the genus comprehensive studies with electron microscopy and evaluation of pollen evolution are lacking. Therefore, we studied pollen morphology in a sample of 65 individuals from 37 taxa covering all the sections distributed in the world, using scanning electron microscopy. Our collection of 49 individuals from 21 taxa covering all five sections in China was also included in the database. We found pollen tetrads in L. bakerianum. Based on present and previous studies, our results suggest that pollen from L. formosanum should be classified as a new type, Formosanum. Combined with morphological and molecular evidence, pollen sculpture patterns appear to reflect phylogenetic relationships and are useful for species or subsection delimitation. Based on a comprehensive survey and correlation with potential functional implications, we propose the following hypothesis: evolution of an exine sculpture shows pollen type trends from Martagon → Callose → Concolor → Formosanum. The evolutionary trend regarding pollen sculpture and size could be related to selective pressure to adapt to environmental conditions. Pollen size and shape showed a significantly positive correlation with annual precipitation, and smaller pollen grains appear to adapt better in habitats with extreme conditions. Evolution trends in exine sculpture do not appear to be definitively correlated with pollen size and shape.     

Pollen morphology,ultrastructure and taphonomy of the Neuradaceae with special reference to Neurada procumbens L. and Grielum humifusum E.Mey. ex Harv. et Sond.

Pollen morphology and sporoderm ultrastructure of modern Neurada procumbens L. and Grielum humifusum E.Mey. ex Harv. et Sond. were studied using light (LM) and electron (SEM and TEM) microscopy. Additionally late Holocene pollen of the Grielum-type was studied using LM. Systematic and ecological aspects have been discussed for the family Neuradaceae. The pollen grains of the studied species are characterized by similarities in size, shape, aperture type and differences in exine sculpture (reticulate semitectate exine in Neurada and finely reticulate to foveolate in Grielum) and sporoderm ultrastructure. The cavea in the exine is situated between the ectexine and endexine which are connected near the aperture region only. A combination of the palynological characters of the Neuradaceae (semitectate exine, rather loose columellae, interrupted foot layer, the cavea in the exine) increases the pollen plasticity, allowing considerable changes of the pollen grain volume but still remains insufficient to survive sharp fluctuations in hydration level.     

Pollen morphology of Campanula (Campanulaceae) and allied genera in Iran with special focus on its systematic implication

Pollen grains of 47 taxa of Campanulaceae including 35 taxa of Campanula that represent its five subgenera and nine sections are investigated. Moreover, five species and three subspecies representing three sections in Asyneuma and one species of each genera Legousia, Michauxia, Zeugandra and Theodorovia were studied by light and scanning electron microscopy. The basic shape of the pollen grains was spheroidal. The apertures vary from tri- to hexa-porate. The sculpturing pattern of exine was rugulate-echinate, rugulate-microechinate or in few species rugulate-microreticulate and microechinate. The most valuable characters for subgeneric classification were the length and density of echini. The length of echini were significantly long (> 2 μm) in C. sclerotricha, Legousia falcata and Michauxia laevigata. Pollen grains show low variation in different species of subgen. Rapunculus, but were variable among different species of some groups, such as sect. Rupestres, probably indicating their non-monophyly despite homogeneity with respect to other morphological characters. Pollen morphology does not support recognition of Asyneuma, Legousia, Michauxia, Symphyandra, Theodorovia, and Zeugandra as separated from Campanula, since none of them exhibit any unique feature.     

Comparative pollen morphology of the Iberian species of Pulicaria (Asteraceae, Inuleae, Inulinae) and its taxonomic significance

To better understand the taxonomy of Pulicaria, the pollen wall architecture of the six Iberian species were investigated using light (LM) and scanning electron microscopy (SEM). The exine structure of Pulicaria odora was also investigated using transmission electron microscopy (TEM). Statistical analysis was performed to distinguish taxonomically significant morphometric information from all the measured parameters of pollen grains. It was found that the exine sculpture characters, with special importance paid to the spines, were the most useful of all characters to define Pulicaria pollen types and separate the species. Three pollen types distinguishable through the spines morphology and the inter-spinular sculpture are described: P. microcephala pollen type (incl. P. microcephala), P. vulgaris pollen type (incl. P. vulgaris), and P. dysenterica pollen type (incl. P. dysenterica, P. odora, P. paludosa and P. sicula). A dichotomous key to these Pulicaria pollen types is proposed. The distribution of P. dysenterica, P. odora, P. paludosa and P. sicula in more than one leaf node in the classification tree reveals that the pollen grains of these species are difficult to segregate. Therefore, the construction of a satisfactory dichotomous key to the P. dysenterica pollen type species is not feasible. Yet, the different spines apex morphology between P. microcephala and P. paludosa and the existence of significant differences in five of the eight studied quantitative pollen characters of these two taxa, supports the opinion that the Berlengas Islands endemic P. microcephala should be accepted as a separate species. In addition, the differences among the spines morphology of P. vulgaris, P. microcephala, and the other four Iberian (and European) species, strengthen the conclusion that the section Pulicaria is non-monophyletic.     

中国紫金牛属圆齿组花粉形态研究及其分类学意义

利用扫描电子显微镜对紫金牛属圆齿组20种1变种植物的花粉形态进行了研究,并比较分析了腋序组2种及锯齿组1种的花粉。经观察花粉为近球形或近扁球形,具3孔沟,除锯齿组的月月红外,其余种均形成合沟。外壁纹饰可分为四类:穴网状、细网状、皱波状及细颗粒状(带刺突)。结果显示,花粉形态特征可作为属下分组及组下分类处理的依据。     

山茶属的花粉形态及其分类学意义

本文对山茶属(Camellia L.)18个组27个代表种的花粉进行了光学显微镜、扫描电镜和大部分进行了透射电镜的观察,并对花粉大小、形状、外壁纹饰和超微结构等作了综合的比较。结果表明,其形状和大小差异不很明显。花粉壁的层次、厚度和不同层次的比例,如复盖层与柱状层以及外壁外层与外壁内层的比例等也没有显著的差异。但花粉壁的纹饰特征在扫描电镜下显示出较大的差异,具有较重要的分类学价值。根据其纹饰特征,可以把山茶属花粉大致区分为六个类型:皱疣状纹饰;粗瘤状纹饰;颗粒状至皱-颗粒状纹饰;穴-网状纹饰;皱沟状纹饰及皱波-念珠状纹饰。孢粉学上区分的类型不完全与各个学者从植物形态上划分的组相一致。其中管蕊茶 Camellia lanceolata的纹饰非常特殊(粗瘤状),其外壁表面很象牛心果(Annona reticulata)的外形特征,为其重新分类提供孢粉学依据。     

Comparative structure of the pollen in species of Passiflora: insights from the pollen wall and cytoplasm contents

Pollen grains of three Brazilian species of Passiflora (P. elegans, P. suberosa and P. haematostigma) belonging to different subgenera were studied with respect to the wall and cytoplasm. New data were obtained on pollen wall histochemistry, cytoplasm contents and organelle inheritance. The structure of the pollen wall layers differed in all the species; P. elegans shares characters with those found in other species from the same subgenus. The exine foot layer is structured and evident only in P. haematostigma and is not structured in P. elegans. The pollen grains have pollenkitt with lipid components. The cytoplasm of the vegetative cell contains dissolved and non-dissolved polysaccharides. The generative cell contains plastids and mitochondria in all the species analyzed, and consequently has the potential for paternal or biparental extranuclear inheritance. Aspects of the evolution of the characters of the species are discussed in the light of a recent phylogeny of the group, with a focus on the three subgenera.     

Pollen morphology and phylogenetic relationships in neotropical Phyllanthus (Euphorbiaceae)

In order to provide new insights into phylogenetic relationships among the neotropical taxa of Phyllanthus , 28 illustrations are provided of the pollen grains of 22 selected species studied from 11 sections of the subgenera represented in the neotropics. Special attention has been given to subgenus Conami because of its variability in pollen morphology: of eight species illustrated, the apertures are diploporate colpi in three species and pores in five species; exine ornamentation is vermiculate in two species and pilate in the other six species. The six species in the neotropical sections Pityrocladus and Microglochidion (subgenus Emblica ) are characterized by prolate grains with an increased number of colpi (4–8). Of particular interest are species in which the pollen exine is clypeate (with exine shields); clypeate pollen grains are illustrated in two species of subgenus Xylophylla and in one species of section Cyclanthera that has unique exine shields with single central pila. The pollen of the one Brazilian phylloclade-bearing species illustrated (in section Choretropsis ) has 3-colporate grains with reticulate exine, typical for subgenus Phyllanthus , and very different from the clypeate grains of the West Indian phylloclade-bearing species in section Xylophylla . This pollen evidence clearly demonstrates homoplasy in the origin of phylloclades in Phyllanthus . Pollen morphological data suggest that the neotropical taxa of Phyllanthus have arisen following colonization from Africa (subgenus Kirganelia ) and Asia (subgenus Emblica ). © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 138 , 325–338.     

POLLEN MORPHOLOGY IN THE GENUS ERYTHRONIUM (LILIACEAE) AND ITS SYSTEMATIC IMPLICATIONS

Pollen morphology was examined in 40 samples from 19 species in the genus Erythronium (Liliaceae) using scanning (SEM) and transmission electron microscopy (TEM). Pollen grains are monosulcate monads, except for a plant of E. oregonum which has dyad grains. North American and European species are characterized by reticulate exine sculpture composed of various degrees of wavy muri and variably-sized lumina. The most distinctive feature of exine sculpture in the genus is exhibited by the Asian species E. japonicum, which has a unique reticulate pattern composed of striate muri and a distinctive exine structure without columellae. The distinctness of E. japonicum pollen suggests that it has specialized in isolation from species in North America and Europe.     

Taxonomic implications of pollen exine morphology in infrageneric classification of Scutellaria (Lamiaceae)

Scutellaria L. in Lamiaceae subfamily Scutellarioideae is a subcosmopolitan genus with about 360 species. According to the latest subgeneric classification, two subgenera are recognized: S. subgen. Scutellaria and S. subgen. Apeltanthus. We studied pollen grains from 29 species of Scutellaria belonging to both subgenera and from both the Old and the New World to evaluate their taxonomic importance for the infrageneric classification of the genus. Pollen grains were acetolysed and studied by scanning electron microscope (SEM) and light microscope (LM). All examined pollen grains are isopolar, tricolpate, suboblate, oblate spheroidal, prolate spheroidal to subprolate. The exine is mainly bireticulate perforate, but with variations in lumina shape and size as well as perforation size and uniformity. Based on the exine sculpturing, two subtypes are recognized within the bireticulate pollen type. In subtype I the primary reticulum of the exine consists of angular muri; the lumen has an irregular polygonal shape and the perforations of the secondary reticulum are more or less uniform and of the same size. This pollen subtype was observed in species of subgenus Scutellaria, sectt. Scutellaria p.p., Anaspis, Perilomia and Salazaria. In subtype II the primary reticulum of the exine consists of a more or less curved murus; the lumen is rounded or obtusely angular and the secondary reticulum consists of one or more large central perforations surrounded by some smaller ones. This pollen subtype was observed in species of subgenus Scutellaria sectt. Scutellaria p.p., Salviifoliae and in all members of subgenus Apeltanthus. The results of this study reveal that the exine ornamentation is a diagnostic character useful for the infrageneric classification of Scutellaria.     

Pollen Morphology of Parnassia L. （Parnassiaceae） and Its Systematic Implications

The pollen morphology of 28 species of Parnassia L. was investigated with light microscopy and scanning electron microscopy (SEM). The shape of pollen grains in this genus varies from subspheroidal to prolate in equatorial view and is three-lobed circular in the polar view. Pollen grains are usually radially symmetrical, isopolar, tricolporate or syntricolporate, with reticulate sculpture. The pollen characteristics among species are fairly similar to each other. Morphological information regarding the pollen grains shows that Parnassia is a natural genus. Based on exine ornamentation observed under SEM, three types of pollen grains were recognized: (i) type I, with foveolate-reticulate sculpture; (ii) type II, with a finely reticulate sculpture; and (iii) type III, with a coarsely reticulate sculpture. Most sections of this genus have one type of sculpture of pollen morphology, but Sect. Nectarotrilobos has three types of sculpture and Sect.Saxifragastrum has two types of sculpture. All three types of sculpture can be found in Southwest China,with species with the longest (Parnassia delavayi Franch.) and shortest (Parnassiafaberi Oliv.) colpi,implying that Southwest China is the center of diversification of the genus.     

Morphology,reserves and pollen viability of some Solanum Sect. Cyphomandropsis species

The morphology, energy reserves and viability of three species from Solanum Sect. Cyphomandropsis (Solanum adelphum Morton, S. glaucophyllum Desf. and S. stuckertii Bitter), which grow in Argentina were studied. The pollen grains are tricolporate and their characters are homogeneous. The only differences found among the species were the pollen grain size and the sculpture distribution. The surface features of exine were not readily visible under light microscope, but with SEM the sculpture appeared granulate. Analyses of the cytoplasm of pollen grains show the presence of oils. The average viability was high in two of the studied species (S. adelphum and S. glaucophyllum). An interesting difference was observed between the first and second day flowers of S. stuckertii. The second day flowers had high fertility but those from the first day had a very low fertility. In the latter case, an inner placentoid tissue of the anther hinders pollen release until the entire development is completed. The P/O ratio is linked to the breeding system.     

Pollen Morphology of Parnassia L. (Parnassiaceae) and Its Systematic Implications

The pollen morphology of 28 species of Parnassia L. was investigated with light microscopy and scanning electron microscopy (SEM). The shape of pollen grains in this genus varies from subspheroidal to prolate in equatorial view and is three-lobed circular in the polar view. Pollen grains are usually radially symmetrical, isopolar, tricolporate or syntricolporate, with reticulate sculpture. The pollen characteristics among species are fairly similar to each other. Morphological information regarding the pollen grains shows that Parnassia is a natural genus. Based on exine ornamentation observed under SEM, three types of pollen grains were recognized: (i) type Ⅰ, with foveolate-reticulate sculpture; (ii) type Ⅱ, with a finely reticulate sculpture; and (iii) type Ⅲ, with a coarsely reticulate sculpture. Most sections of this genus have one type of sculpture of pollen morphology, but Sect. Nectarotrilobos has three types of sculpture and Sect.Saxifragastrum has two types of sculpture. All three types of sculpture can be found in Southwest China,with species with the longest (Parnassia delavayi Franch.) and shortest (Parnassia faberi Oliv.) colpi,implying that Southwest China is the center of diversification of the genus.