绣球属(Hydrangea L.)及近缘属花粉形态的研究

为深入研究绣球属植物花粉形态的分类学价值和系统学意义,厘清绣球属与近缘属之间的系统发育关系,该文利用扫描电子显微镜(SEM,scanning electron microscope)对国产绣球属及其近缘属41种绣球花科(Hydrangeaceae)植物的花粉形态以及表面纹饰进行了观察。结果表明:绣球属及其近缘属的花粉为三孔沟;形状多数为长圆体形或近球体形;赤道面观为椭圆形或圆形;极面观多为圆形,少数为三角形或圆三角形。花粉外壁纹饰可分为网状和孔穴状。网眼内的三级纹饰可分为光滑和具颗粒状突起。根据花粉形状和外壁纹饰类型将上述物种划分为4个组,即花粉的形状为长圆体形,表面纹饰为孔穴纹饰;花粉的形状为长圆体形,表面纹饰为网状纹饰;花粉的形状为近球体形,表面纹饰为孔穴纹饰;花粉的形状为近球体形,表面纹饰为网状纹饰。以上可进一步细分为8个类型。上述表明花粉形态证据可为绣球属及其近缘属的属下分类和种间界定提供重要佐证;但结合前人的系统发育重建分析该属植物花粉形态的系统学意义相对有限,如花粉形态证据对于该属及其近缘种属系统发育树上大支的界定难以提供有力的证据。     

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 the genus Salvia L. (Lamiaceae) in Turkey

Pollen grains of 30 taxa of the genus Salvia, belonging to sections Salvia, Horminum, Drymosphace, Plethiosphace and Hemisphace from Turkey were examined by light (LM) and scanning electron microscopy (SEM). Detailed pollen morphological characteristics are provided for these taxa. Among the studied taxa, S. verticillata subsp. verticillata from sect. Hemisphace has the smallest pollen grains, and S. pachystachys from sect. Salvia possesses the largest ones. The basic shape of the pollen grains in most taxa is suboblate, oblate-spheroidal or prolate-spheroidal. However subprolate pollen grains are recorded for S. macrochlamys from sect. Salvia. The grains are hexacolpate in all taxa, but in S. recognita from sect. Salvia also octacolpate pollen was found. Three distinct exine sculpturing types exist, reticulate-perforate (the common type), reticulate-granulate and bireticulate. The reticulate-perforate and bireticulate sculpturing patterns can be divided into subtypes based on the number of perforations and the number of secondary lumina in each primary lumen. Pollen morphological characteristics of the taxa studied are compared and discussed on the basis of taxonomical concepts. In some cases, these characters are useful in distinguishing the sections. For instance, the presence of 1-2 large central secondary lumina per primary lumen is a significant character of sect. Horminum separating it from the other sections. As well, the presence of holes on colpus membrane ornamentation can be used as a diagnostic taxonomic character for sectional division between sect. Hemisphace and others. S. ballsiana from sect. Salvia is clearly distinct from the other taxa examined by its unique pollen morphology. Further, for several macromorphologically similar taxa pollen structures provide additional evidence to delimite them from each other.     

ONTOGENETIC AND EVOLUTIONARY IMPLICATIONS OF A NEOTENOUS EXINE IN TAPEINOCHILOS (ZINGIBERALES: COSTACEAE) POLLEN

Tapeinochilos pollen, like that of most angiosperms, is spared by the standard acetolysis treatment because the sporoderm is impregnated with sporopollenin. This genus and its allies in the Costaceae are the only taxa in the eight families of Zingiberales that have acetolysis-resistant pollen. The sporoderm in most of the order is characterized by exine reduced to a wispy coating or layer with delicately anchored spinules and a highly elaborated intine. Ultrastructural studies on the pollen of Tapeinochilos reveal a pattern of wall development that is significantly different from the generalized angiosperm type; namely, there are no columellae, nor is there any significant accretion of sporopollenin following the dissolution of callose and release of microspores. The primexine is composed of rodlets which build up solidly between apertures and become packed into layers to form a thick, stratified exinous covering. No secondary exine develops during the free spore period and the juvenile primexine persists as the protective coat on the mature pollen grain. This pattern of pollen development is viewed as an example of neoteny in which a juvenile or immature character is retained in adulthood.     

Pollen morphology in relation to floral types and pollination syndromes in Pedicularis (Orobanchaceae)

Floral diversification in the genus Pedicularis (Orobanchaceae) is remarkable among flowering plants. In this genus, floral morphology and pollinator behavior are closely co-adaptive. In the current paper, pollen grains of 23 representative species of Pedicularis mainly from North America, with two species from Japan and two species from China, whose pollination ecology was previously studied, were examined using light microscopy and scanning electron microscopy. Two pollen aperture types and three kinds of exine ornamentation were recognized among these species. In addition, pollen data from previous and the current studies of Pedicularis were integrated and analyzed, together with some pollination characters. There was a significant association between pollen aperture types and corolla types, as well as between pollination syndromes and corolla types. However, there was no association of exine ornamentations with corolla types. The relationships and evolution of this genus were discussed with regards to pollen morphology, corolla types and pollination syndromes.     

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 diversity in the genus Ptilostemon (Asteraceae,Cardueae) from Italy and its taxonomic and palynoecological implications

The results of a study on pollen morphology of the species of the genus Ptilostemon growing in Italy: Ptilostemon niveus, P. greuteri, P. gnaphaloides, P. casabonae, P. strictus, P. stellatus by light and scanning electron microscopy were presented and discussed including in relation to their taxonomic position. The exine shows two different ornamentation patterns: echinae and scabrae. This last ornamentation pattern together with other features was previously described in the genus Ptilostemon. Of 6 species analysed, P. stellatus is the only one that shows a scabrate ornamentation of exine. Two pollen types were recognized through the exine ornamentation, length of ectocolpus and polar outline: P. stellatus type and P. niveus type. A multivariate analysis (principal component analysis and linear discriminant analysis) was carried out with the aim of examining potential morphological characters which could be used to identify taxa. The data suggest that several characteristics can be used to delimit the species in particular the exine ornamentation. The results of our studies support the actually subgeneric classification, and several features of the pollen grains analysed seem to have a palynoecological role and an important taxonomic significance. A dichotomous key based on palynological data is also given.     

Variation of pollen morphology, and its implications in the phylogeny of Clematis (Ranunculaceae)

Clematis s.l. (including Archiclematis and Naravelia) is a genus of approximately 300 species with cosmopolitan distribution. The diversity of its pollen was surveyed in 162 taxa belonging to all infrageneric groups of Clematis s.l. Pollen morphology was investigated by use of scanning electron microscopy to identify useful characters, test taxonomic and systematic hypotheses, and elucidate pollen character evolution on the basis of the molecular phylogeny. Clematis pollen is small to medium (14.8–32.1?μm?×?14.2–28.7?μm), oblate to prolate (P/E?=?0.9–1.4) in shape. The apertures may be tricolpate and pantoporate sometimes with 4-zonocolpate and pantocolpate pollen grains as transitional forms. The tricolpate pollen grains are predominant and occur in all the sections of the genus, whereas pantoporate pollen grains can be found in sect. Tubulosae, sect. Viorna, sect. Viticella, and Naravelia only. Phylogenetic mapping of aperture types reveals that the pantoporate pollen type may be the apomorphy in the genus and evolved several times. The surface ornamentation in all taxa studied is similar and characterized by microechinae evenly distributed on the microperforate tectum. The size and density of spinules on the tectum vary greatly but successive in the whole genus. According to the character syndromes of the ornamentation, separating sect. Brachiata from sect. Meclatis is supported. Though pollen morphology may contribute to investigation of problematic taxa, the taxonomic value of pollen morphology is limited at the species level.     

The fine structure of the pollen wall inStrelitzia reginae (Musaceae)

The pollen wall ofStrelitzia reginae (Musaceae) consists of a nearly unsculptured, very thin, highly reduced, but coherent exine, and a thick intine (with an outer, channeled layer and an inner, largely homogeneous layer). After short, incomplete acetolysis the exine covers the remaining, severely shrinked protoplast as a folded, but unaltered “skin”, while the intine has totally disappeared. After extended acetolysis only the coherent, skin-like exine remains. Thus, the term “exine-less pollen” sometimes used for similar sporoderm structures in other genera ofZingiberales is misleading and should be substituted by the term “skin-like exine”. Surprisingly, the peculiar pollen wall ultrastructure ofStrelitzia and some otherZingiberales is very similar to that of some genera of theLaurales, an example for convergent evolution within the angiosperms.     

Two novel reports of semidry stigmatic surface in Asteraceae

Research documents related to the morphology and function of style branches and stigmatic surface of Asteraceae are still rather few, and the literature reports are thus controversial. We report in the present study that the stigmatic surfaces of two non-related species of Asteraceae (Lessingianthus grandiflorus and Lucilia lycopodioides) have features of semidry stigmas. Sporodermis of both species was also analyzed so that we could understand how the stigmatic surface works during pollen deposition and rehydration. Stylar branches and pollen grains (sporodermis) were studied using scanning and transmission electron microscopy (SEM and TEM) and histochemistry techniques. The inner and marginal bands of stylar branches in these species display intermediary features between the dry and wet types of stigma: the cuticle characterizes the dry stigma and cells with secretory activity characterize the wet stigma; these showed differences from what has been described to the Asteraceae family, where stigmatic surface of species from several tribes is considered dry. Pollen grains are medium-size to large with exine ornamentation (echinate and echinolophate) and abundant secretion which latter characterizes pollenkitt. We can assume that two processes might help pollen grain hydration on stigmatic surface in Lessingianthus grandiflorus and Lucilia lycopodioides: (1) the presence of pollenkitt, as observed in the secretory content inside exine cavities and around pollen grains; and (2) the secretory activity of stigmatic surface cells, whose secretion accumulates among intercellular and subcuticular spaces and leads to cuticle disruption during the floral receptive phase. Our results suggest that ultrastructural and histochemical studies should be considered when describing stigmatic surface and that the “semidry” feature within Asteraceae should be investigated still more in detail, so that the taxonomic or adaptation value of this trait in the family can be verified.     

Pollen morphology and its systematic and ecological significance in Rheum (Polygonaceae) from China

Pollen morphology of 40 species of Rheum , belonging to eight sections, was investigated under LM and SEM. Four new exine patterns were found in the species: a) microechinate-foveolate, b) rugulate, c) verrucate-perforate, and d) verrucate-rugulate ornamentation. In addition, two patterns, the Rheum-type pollens with microechinate-perforate and fine-reticulate, as previously described, were also confirmed in the present study. Based on above study the evolution trends of pollen morphology in the taxa involved were discussed phylogenetically as below. As microechinate-perforate exine pattern existed commonly, the pattern is, therefore, regarded as the most primitive among all the six types. The fine-reticulate type was thought as a derivative type, deriving from the basic microechinate-foveolate-perforate pattern, and followed by the rugulate and verrucate-perforate ornamentation. The verrucate-rugulate ornamentation should be the most advanced. More than one pollen type often exist in most of the sections in Rheum. The pollen morphology of Rheum was strongly correlated with its geographical and ecological distribution. Three medicinally important species R. officinale, R. palmatum and R. tanguticum can be palynologically distinguished by their ornamentations.     

新疆石竹属8种植物的花粉形态

利用扫描电镜对8种石竹属（Dianthus）植物的花粉形态进行了观察。结果表明:本属植物花粉为单粒花粉,圆球形,大小为30.5~44.0 μm,具多个萌发孔,孔数为12~16个,分散,孔圆形,孔径4.1~7.0 μm,具孔膜,孔膜上着生有若干棵小刺,花粉外壁具刺状和穴状纹饰,表面有或无穿孔。研究表明：花粉大小、表面纹饰、特别是萌发孔的形态特征存在较明显差异。可为石竹属植物的分类及野生资源利用等相关研究提供了可靠的孢粉学参考。     

大吴风草属、假橐吾属花粉表面纹饰及其分类学意义

观察了千里光族款冬亚族中大吴风草属,假橐吾属及其相关类群5属共8种植物在扫描电镜下的花粉性状,所有种类的花粉外壁均为刺状纹饰,但在刺的长短,刺部是否膨大、刺基膨大上的纹饰以及刺基之间的纹饰等方面存在差别,大吴风草的花粉外壁性状不同于橐吾属,从而不支持它与后者有较近亲缘关系的观点它与花粉超薄结构同为“向日葵型”的多榔菊属的花粉外壁性状也不相同,假橐吾属不同于橐吾属和垂头菊属的花粉外壁性状,研究结果支持本单种属的成立。     

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 EVOLUTION OF POLLEN TETRADS IN ONAGRACEAE

In Onagraceae, pollen is shed in mature tetrads in most Epilobieae, many species of Ludwigia (Jussiaeeae), and two closely related species of the large genus Camissonia (Onagreae). Mature tetrads of Camissonia cardiophylla and representative species of Epilobium and Ludwigia were examined with light, scanning, and transmission electron microscopes. Morphological diagnoses of monad units indicated that individual taxa could be readily distinguished. Statistical analyses of tetrads which remained after acetolysis treatment revealed significant differences in the strength of the binding mechanisms. Mechanisms of tetrad cohesion were found to consist of two principal types. Common to all taxa is cohesion of pollen wall surfaces at the aperture margins; this mechanism is well known in many angiosperm groups. With the exception of Camissonia, the remaining taxa also display binding by means of short exine fragments between adjacent pollen units. These fragments, termed bridges and reported here for the first time, are located in the area extending from the aperture margins to near the center of the proximal exine faces. Thin sections reveal that layers of the bridges are identical with those of the exine. Comparisons were made between bridges and viscin threads, both of which occur on the proximal faces of the grains. Viscin threads are present on all pollen grains in Onagraceae and exhibit distinctive morphologies, and bridges were viewed morphogenetically as related to viscin threads but including an endexine layer and occupying a position near the apertures where cohesion of wall surfaces also occurs. In an evolutionary sense, the formation of mature tetrads almost certainly occurred independently in Camissonia and may have done so in Ludwigia and the Epilobieae.     

Pollen Morphology of Plants from the Hengduan Mountains and Their Ecological Significance

Pollen morphology of selected taxa from the Hengduan Mountains, Southwest China are investigated in the present study. Forty eight taxa (flowering in the summer, 46 species and 2 varieties) of 43 genera belonging to 27 families were observed by light and scanning electron microscopy. Pollen morphology is described in detail. Two pollen shapes are mainly found in these species: subprolate to prolate (271%) and prolate (25%). Spheroidal, subspheroidal to subprolate, suboblate and tetrad shapes can also be found in some species. Aperture type is mostly tricolporate, with a percentage of 438, and also contains tricolpate, pantoporate, stephanocolpate, 3 colporoid, 6 colpate, monocolpate. The most common ornamentation is finely reticulate, with a percentage of 50. Other exine ornamentations, such as coarsely reticulate, finely granulate, smooth, spinulose are also observed. The palynological documentation of these species will provide the modern palynological basis for paleopalynological studies of the Quaternary Strata. On the basis of pollen morphology characters, identification features of some species in the same families were discussed according to the results of cluster analysis used by SPSS. The ecological significance was also discussed based on the ecological properties of these taxa.     

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

The pollen morphology of forty taxa of the genus Nepeta L. was studied and documented in detail using light microscopy (LM) and scanning electron (SEM) microscopy in this study. Nepeta L. pollen grains are small to large (P = 18.64–63.46 μm, E = 15.62–46.33 μm), suboblate to perprolate (P/E = 0.86–2.09) in shape and hexacolpate (very rarely tetracolpate) with granular membranes. Alternate position of colpi occurs in six Nepeta taxa, N. nuda ssp. glandulifera, N. concolor, N. crinita, N. congesta var. cryptantha, N. stricta var. stricta and N. sibthorpii ssp. tumeniana. In examinations of exine ornamentation with SEM, two types of pollen grains were recognized: (1) type I, with microreticulate sculpture; and (2) type II with bireticulate sculpture, type I and II to be divided into two and five subtypes, respectively. In the two taxa with microreticulate pattern, N. pilinux and N. sulfuriflora, a tendency towards a bireticulum could be recognized due to traces of secondary tectal connections. The bireticulate exine ornamentation is characterized with varying characteristics of the primary muri and secondary reticulum. Pollen morphology within the genus is compared with infrageneric relationships.     

Pollen morphology of the genera Polygonum s. str. and Polygonella (Polygoneae: Polygonaceae)

The pollen of 30 taxa (27 species, one subspecies and two varieties) in two genera, viz Polygonum s. str. and Polygonella was investigated with LM and SEM, and some selected taxa with TEM. In all genera investigated the pollen is prolate to spheroidal, and the aperture is mostly tricolporate, rarely panto-hexacolporate (especially Polygonum section Polygonum). The exine sculpturing pattern is the most variable feature. Three types of exine can be recognized. Type 1 (Avicularia-Type, sensu Hedberg) - All species of section Polygonum and section Tephis share the smooth tectate exine with spinules, sometimes the surface is more or less rough (Polygonum afromontanum in section Tephis). Type 2 (Pseudomollia-Type, sensu Hong) - Pollen of Polygonum molliaeforme (section Pseudomollia) has the exine, which is verrucose on both poles and nearby the mesocolpium, and mostly psilate around the ectoaperture. Type 3 (Duravia-Type, sensu Hedberg) - Pollen grains of Polygonum section Duravia and Polygonella have the exine which is semitectate-reticulate at the mesocolpium and the poles, and rugulate/reticulate or sometimes foveolate with microspinules around the ectoapertures. The pollen grains in four taxa (viz Polygonum section Pseudomollia, P. section Duravia and genus Polygonella) have a well-marked dimorphism of the ektexine, which is considered to be a synapomorphic condition. The differences of pollen grain between the genus Polygonella and Polygonum section Duravia are almost non existent and clearly interrelated. It is therefore postulated that the similarity in pollen of both taxa is not the result of convergency, but is interpreted as a homology. It is noteworthy that the pollen of Polygonum molliaeforme (section Pseudomollia) appears as intermediate between the Avicularia-type and the Duravia-type, and is well supported the value of separated section for its own. Additionally, in TEM, some exine ultrastructures (e.g. columellae, foot layer, endexine) appear to be valuable characters for comparison between/among taxa. The systematic potentialities of the pollen data of the studied taxa at various systematic levels are also discussed.     

Pollen Morphology of the Family Zingiberaceae in China—Pollen Types and Their Significance in the Taxonomy

Pollen morphology of 89 species and 3 varieties belonging to 18 genera (out of 150 spcies in 20 genera) of Zingiberaceae in China was studied under both light microscope and scanning electron microscope. Pollen grains of Zingiberaceae are spherical, subspherical, ovoid and prolate, 36-225 μm in size, nonaperturate or aperturate (spiraperturate, porate). Pollen grains are almost not resistant to acetolysis. The wall is composed of a very thin exine and a thick intine. The exine is psilate, spinate, cerebelloid-areolate, striate, verrucate and foveolate. According to the presence or the absence of aperture and differential ornamentations, two types and six subtypes are recognized: I. The type Nonaperturate: (85 species and 3 varieties in 18 genera). Four subtypes can be recognized within the type based on the characteristics of the exine sculpture. These are: (1) The subtype Psilate, in which, the exine is nearly smooth (including: Hedychium, Curcuma, Kaempferia, Caulokaempferia coenobilis, Boesenbergia rotunda, Stahlianthus, Amomum compactum, Etingera, Hornstedtis, Rhynchanthus). (2) The subtype Spinate, which comprises two groups: (A) The group Short-spinate, pollen grains with smaller spines (Globba), (B) The group Long-spinate, pollen grains with longer spines (Alpinia, Amomum, Plagiostachys, Roscoea, Cautleya, Boesenbergia fallax, Caulokaempferia yunnanensis). (3) The subtype Cereblloid-areolate, pollen grains of which are spherical or subspherical, with cerebelloid sculpture (Zingiber Sect. Zingiber). (4) The subtype Striate, pollen grains of which are prolate or oliveshaped, and striate (Zingiber Setc. Cryptanthium). II. The type Aperturate, in which pollen grains are acetilysis-resistant and possess distinct apertures (mixed colpate-porate or forate), including two subtypes: (1)The subtype Mixed colpate and Porate. Pollen grains are both 3-colpate and 1-3-porate, and usually with one long spiral, two short (straight or slightly curved) colpi and 1-3-poris. The exine is verrucate or not, nearly sinuolate (Costus speciosus, C. tonkinensis, C. lacerus). (2) The subtype porate, whose grains are 6-8-porate and exine is foveolate (Costus megalobractea). The taxonomic significance of the pollen types in the family Zingiberaceae is also discussed.     

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.