Exine Sculpture Research Articles

Morphological variation of Nymphaea (Nymphaeaceae) in European Russia

The morphological variability of the genus Nymphaea is described on the basis of detailed studies of fresh material from 49 populations in European Russia and southern Siberia.Macromorphological characters in the field (including analysis of leaf shape using geometrical morphometry), pollen size and exine sculpture have been analyzed. One polymorphic widespread species, N. candida, grows in most of European Russia. Nymphaea tetragona seems to be absent in the investigated waters and possibly in the whole central part of European Russia, whereas N. alba was found only in the Astrakhan Region (the delta of the River Volga). These three species are separated relatively well by several morphological characters in fresh plants. Nymphaea tetragona differs from N. alba and N. candida by the sculpture of the exine of the proximal part of the pollen grains, but the latter species do not seem to be differentiated by pollen characters. Size characters of Nymphaea leaves and flowers do not depend on organic content in water.

Caracterização palinológica de espécies de Amaryllidaceae sensu stricto ocorrentes no nordeste brasileiro

Este trabalho teve com objetivo realizar as descrições polínicas de espécies nordestinas de Amaryllidaceae s.s. e Alliaceae e relacioná-las visando a sua delimitação taxonômica. Foram analisadas as espécies: Griffinia espiritensis Ravenna var. bahiana Preuss & Meerow, Griffinia gardneriana (Herb.) Ravenna, Habranthus itaobinus Ravenna, Habranthus robustus Herb, ex Sweet, Habranthus sylvaticus Herb., Hippeastrum puniceum (Lam.) Kuntze, Hippeastrum stylosum Herb., Hymenocallis littoralis Salisbury Zephyranthes cândida (Lindl.) Herb, e Nothoscordum pernambucanum Ravenna. As descrições foram feitas a partir da análise de grãos de pólen acetolisados (ou não) observados em microscopia óptica e eletrônica de varredura, os quais foram obtidos de espécimes recém-coletados. Todas as espécies apresentaram grãos de pólen em mônades, heteropolar-bilaterais, monossulcados e âmbito elíptico/elipsoidal. Foram detectadas características diagnosticas com relação ao padrão de ornamentação, destacando Hippeastrum stylosum Herb, e Hymenocallis littoralis Salisbury por possuírem grãos de pólen com calotas equatoriais. As características polínicas analisadas foram suficientemente relevantes para a delimitação específica dentre os táxons analisados.

Morphological diversity of the exine sculpture of some Frasnian spores from the northern Timan: Applications for taxonomy and significance for spore dispersal

Microspores and megaspores from micro-and megasporangia of a Late Frasnian plant from the northern Timan are identified as the genus Cristatisporites and Ancyrospora, respectively. The exine sculpture is studied in in situ spores, as well as in dispersed miospores of Cristatisporites, Ancyrospora, and Hystricosporites, found in the rock enclosing the plant. The use of exine appendages as a generic level character is proposed. The shape of appendage extremities and the presence of irregular holes in the exine that are considered to be probable insect feeding damage, allowing us to consider wingless insects as main dispersal agents of the spores.

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, 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.

Pollen Morphology of Acinos Miller Species Growing in Turkey

Abstract The pollen morphology of six taxa of the genus Acinos Miller has been examined under scanning electron microscopy (SEM) and a description of each taxon has been given. Acinos pollen is stephanocolpate (hexacolpate). Two main exine sculpturing types, foveolate‐reticulate (only in subspecies of A. troodi) and reticulate, have been defined. The dimension for the polar length ranges between 25.8–47.4 μm, equatorial width 24.5–34.4 μm, colpus length 20.0–40.5 μm and colpus width 1.2–2.5 μm. The shape is mostly subprolate to prolate, seldomly prolate‐spheroidal. The results reveal rather uniform morphological features, however fine details are characteristic to differentiate the pollen taxa. Acinos pollen also share some common morphological features with the other Lamiaceae pollen.

Pollen Morphology of the Woody Fabaceae in Korea

The pollen morphology of 31 taxa, representing all woody species from 12 genera of Fabaceae in Korea, was examined by light microscope and scanning electron microscope. The pollen grains were monad and prolate spheroidal or rarely subprolate in equatorial view. The pollen grain aperture was trizonocolporate or rarely trizonooperculate, which does not occur in the other families of Fabales in Korea. The exine showed a great variety of sculpture pattern, i.e. psilate, microperforate, densely microperforate, perforate, polygonal perforate, macroperforate, macroperforate with granules in holes, polygonal macroperforate, verrucate with pitted perforate striae, verrucate-perforate, granulate, rugulate, reticulate or refined reticulate. The pollen morphological data supported the idea that the genera Echinosophora and Sophora were congeneric. Caragana (Galegeae) was quite close to the Sophora group (Maackia, Sophora and Echinosophora) of the Sophoreae in each measured pollen parameter and exine sculpture pattern. Eleven genera of Fabaceae were recognized based on differences in aperture type, pollen grain shape and exine pattern, and a generic pollen key of the woody Fabaceae in Korea was developed. A key to pollen types of Lespedeza was also suggested. The examined taxa of Coronilla and Wisteria were recognized by their exine patterns.

凤仙花属（Impatiens L.）10种植物花粉形态的扫描电镜观察

利用扫描电镜观察了10种凤仙花属（Impatiens L.）植物的花粉形态。结果表明：本属花粉为单粒花粉,呈长圆形至长矩圆形,大小为20.3-46.7μm,具角萌发孔,网状纹饰,网眼明显;根据花粉网状纹饰中网眼内是否具颗粒状突起可将其分为2类：（1）网眼内无或近无颗粒状突起,黄金凤（I.siculifer）和婺源凤仙花（I.wuyuanensis）的花粉纹饰属于这一类型;（2）网眼内有明显颗粒状突起,其余8个种的花粉纹饰均属于该类型。研究表明,花粉特征,特别是花粉粒网状纹饰中网眼内有无颗粒状突起及颗粒状突起的形态等特征,在凤仙花属内常具种水平上的可见变异,因而可作为种类划分的依据,它们在分类学上的价值应予以关注。

Pollen polymorphism inThymus capitatus(Lamiaceae)

Polymorphism with respect to size and structural characteristics occurs in pollen grains of several species. Pollen grains of Thymus capitatus (L.) Hoffmans & Link. from three different areas of Greece were collected, and their palynological characteristics were measured. Using light and scanning electron microscopy, a quantification of pollen polymorphism of T. capitatus was achieved by measuring the size and the characteristics of exine sculpture. The measurements were repeated during 3 successive years, and statistical analyses with one-way ANOVA and Duncan’s multiple range test were applied. Results revealed differences in the exine pattern between the locations; also, three palynological characteristics (surface, perimeter, and equatorial diameter) differed statistically. The results clearly indicate that pollen grains of T. capitatus are polymorphic between the sampling areas. The polymorphism has been related to environmental parameters and mainly with water availability. Average rainfall seems to be the main factor contributing to the morphological variation of pollen grains by affecting their size and exine sculpture.

Pollen morphology of Enkianthus (Ericaceae) and its taxonomic significance

Pollen morphology of ten Enkianthus species was examined using light (LM) and scanning electron microscopy (SEM) and previous infrageneric classification of Enkianthus was discussed in the light of the palynological characters obtained in this study. The pollen grains are monads, oblate spheroidal to prolate in shape and 3‐ to 5‐colpor(oid)ate. Exine sculpture varies from granulate to coarsely rugulate‐psilate with faint to distinct minute granules in SEM. Infraspecific geographical differences in palynological characters were found in E. deflexus. The species of Enkianthus are clearly differentiated into two pollen morphological groups that correspond to the sections Enkiantella + Meisteria and Andromedina + Enkianthus, respectively. The members of the sections Enkiantella and Meisteria have pollen grains typically with three apertures, prolate spheroidal to prolate, ratio of colpus length to polar axis (L/P) 0.69–0.84, relatively thinner exine and exine sculpturing tendency to granulate, character states that are probably plesiomorphic in this genus. The members of the sections Andromedina and Enkianthus have more derived pollen grains with four to five apertures, commonly oblate spheroidal, L/P 0.56–0.63, relatively thicker exine and exine sculpturing tendency to coarsely rugulate‐psilate. It seems to be difficult to differentiate between sections of the same group on the basis of palynological characters only. Adding the palynological characters to the infrageneric framework of Anderberg indicates an evolutionary trend in exine sculpture within Enkianthus from finely verrucate‐rugulate through coarsely rugulate to coarsely rugulate‐psilate. A dichotomous key for Enkianthus was prepared based on the palynological characters.

Exine Micromorphology of Orchidinae (Orchidoideae, Orchidaceae): Phylogenetic Constraints or Ecological Influences?

Pollen characters have been widely used in defining evolutionary trends in orchids. In recent years, information on pollination biology and phylogenetic patterns within Orchidinae has become available. Hence, the aim of the presented work is to re-evaluate exine micromorphology of Orchidinae in light of recent phylogenetic studies and to test whether pollen micromorphology strictly depends on phylogenetic relationships among species or whether it is influenced by the marked differences in pollination ecology also reported among closely related species. Pollen sculpturing of 45 species of Orchidinae and related taxa was investigated using scanning electron microscopy. To cover potential intraspecific variation, several accessions of the same species were examined. Orchidinae show remarkable variation in exine sculpturing, with a different level of variation within species groups. In some genera, such as Serapias (rugulate) and Ophrys (psilate to verrucate), intrageneric uniformity corresponds well to a common pollination strategy and close relationships among species. However, little exine variability (psilate-scabrate and scabrate-rugulate) was also found in the genus Anacamptis in spite of striking differences in floral architecture and pollination strategies. A larger variety of exine conditions was found in genera Dactylorhiza (psilate, psilate-scabrate and reticulate) and Orchis s.s. (psilate, reticulate, perforate-rugulate and baculate) where no unequivocal correspondence can be found to either phylogenetic patterns or pollination strategies. Changes in pollen characteristics do not consistently reflect shifts in pollination strategy. A unique trend of exine evolution within Orchidinae is difficult to trace. However, the clades comprising Anacamptis, Neotinea, Ophrys and Serapias show psilate to rugulate or scabrate pollen, while that of the clade comprising Chamorchis, Dactylorhiza, Gymnadenia, Orchis s.s., Platanthera, Pseudorchis and Traunsteinera ranges from psilate to reticulate. Comparison of the data with exine micromorphology from members of the tribe Orchidieae and related tribes suggests a possible general trend from reticulate to psilate.

Pollen Morphology of Eight Genera of the Subtribe Mutisiinae Less. Sensu Bremer (Compositae) from Asia

Abstract: The pollen morphology of 28 species and one variety representing eight genera of the subtribe Mutisiinae Less. sensu Bremer (Compositae) was investigated by scanning electron microscopy (SEM) and light microscopy. The pollen grains are usually radically symmetrical, isopolar, and tricolporate. The shape varies from spheroidal to subprolate in equatorial view and is three-lobed circular in polar view. Based on exine sculpturing observed under SEM, the pollen grains can be divided into three types: (i) type I, with macrogranulate sculpture; (ii) type II, with a finely granulate sculpture; and (iii) type III, with spiny sculpture. The palynological data showed that the Macroclinidium Maxim. was remarkably distinguished from those of the other seven genera. The variation of pollen characteristics within the Mutisiinae in Asia is little at species level, but it proves some useful information for studying the relationships among genera and it has an important significance in further understanding the evolutionary history of Mutisiinae. (Managing editor: Wei WANG)

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 ofArtemisia L. and its systematic significance

The pollen of 57 species representing 7 sections ofArtemisia was examined by light microscope and scanning microscope for the purpose to elucidate the systematic relationships of the genus. The examination indicates that the pollen grains present high concordance which is characterized by the globular or the approximate shape, 3-lobed circular from polar view while granular or ellipse sphere from tropical plate with tricolporate structure. The exine of pollen has an obvious double structure of inner and outer layers (including the tectum and columnar layers) where the outer is thicker than the inner and the sculpture of exine degenerates into small spinules easily distinguishable from other genera of the Compositae. Based on exine sculpture. the pollen grains ofArtemisia can be divided into two types: Myriantha type and Mongolica type, which possesses 4 subtypes according to the distribution forms of spinule: (1) Sacrorum subtype, (2) Oligocarpa subtype, (3) Lavandulaefolia subtype, (4) Anomale subtype.

Pollen morphology of the genus Gagea (Liliaceae) in Iran

Pollen grains of 26 species of the genus Gagea distributed in Iran were examined by light and scanning electron microscopy. Detailed pollen morphological characteristics are given for these species. Among the studied species, the newly described G. iranica together with G. olgae and G. graminifolia possess the smallest pollen grains, and the widely distributed G. lutea the largest ones. Our studies show that the sculpturing of exine provides valuable characters for separating the species, sometimes even for closely related ones, and delimitation of natural groups within the genus. The exine of the genus Gagea is in most cases perforated upon tectum or rarely tectate-columellate. The muri are solid or structured, compound, simpli-, dupli- or pluricolumellate. It seems that the structure of muri is very important in recognizing natural groups within the genus. Tectal perforations vary from <0.2 to 2.0 μm in diameter among the studied species. Regarding sculpturing of the exine in proximal face, four basic types of pollen grains can be distinguished: reticulate, microreticulate, foveolate and perforate. Within the reticulate type there is sufficient variation in exine structure at distal face to describe three subtypes: reticulate, microreticulate and perforate. A diagnostic key is given for all studied taxa based on palynomorphological characters. For a limited number of populations of selected Iranian species of Gagea, further aspects of pollen biology were studied. It seems that populations with ploidy levels other than diploidy, show a low percentage of pollen fertility. Moreover, the rate of pollen fertility is correlated with the manner of the reproduction in certain species.

Heteromorphic Incompatibility and Efficiency of Pollination in Two Distylous Pentanisia Species (Rubiaceae)

Distyly has been hypothesized to promote cross-pollination by reducing intrafloral and geitonogamous self-pollination, and enhancing intermorph pollination. Distylous plants typically display both reciprocal herkogamy and a heteromorphic incompatibility system, which allows mating only between morphs. Distyly and its pollination consequences were examined in two Pentanisia species with long-tubed flowers which are pollinated almost exclusively by butterflies. Anther and stigma heights were measured to quantify reciprocal herkogamy. The type of incompatibility system was determined by observing pollen tubes and seed production following controlled hand pollination. Pollen loads on pollinators and stigmas were also examined to assess the efficiency of intermorph pollen flow. Pentanisia prunelloides and P. angustifolia exhibit reciprocal herkogamy and a host of ancillary dimorphisms, including pollen colour, exine sculpturing, stigmatic papilla shape and floral-tube pubescence. Controlled hand-pollinations revealed the presence of a strong heteromorphic incompatibility system in both species. The site of incompatibility differed between the morphs; intramorph pollen tubes were blocked in the style of the short-styled morph and on the stigmatic surface of the long-styled morph. Butterflies carried pollen from the short- and long-styled morphs primarily on their head and proboscis, respectively. Natural pollination resulted in a higher proportion of pollen transfer from long- to short-styled plants than vice versa. Nevertheless, fruit set did not differ between morphs. Both Pentanisia species are fully distylous. Reciprocal herkogamy results in pollen from the two morphs being carried on different locations on pollinators' bodies, which in turn promotes intermorph pollination. Intramorph pollination does not result in fertilization, because of an effective heteromorphic incompatibility system.

World Pollen and Spore Flora 23. Malvaceae Adams. P.p. Subfamilies: Grewioideae, Tilioideae, Brownlowioideae

The pollen morphology of 85 species (89 collections) from 32 genera, i.e. Ancistrocarpus, Apeiba, Berrya, Brownlowia, Carpodiptera, Christiana, Clappertonia, Colona, Corchorus, Desplatsia, Diplodiscus, Duboscia, Eleutherostylis, Entelea, Erinocarpus, Glyphaea, Goethalsia, Grewia, Hainania, Heliocarpus, Luehea, Lueheopsis, Microcos, Mollia, Mortoniodendron, Pentace, Sparmannia, Tetralix, Tilia, Trichospermum, Triumfetta, and Vasivaea of family Malvaceae was examined by light microscope (LM), scanning electron microscope (SEM) and transmission electron microscope (TEM). Three types are recognized on the basis of aperture types, exine pattern and pollen shape classes 1) Berrya-type, 2) Corchorus-type and 3) Mortoniodendron-type. The Berrya-type has two subtypes: Berrya-subtype A and Berrya-subtype B. Corchorus-type has two subtypes: Corchorus-subtype A and Corchorus-subtype B. In the Berrya-type, Corchorus-type and Mortoniodendron-type pollen grains are colporate, in one case (Tilia) colp(or)ate. The pollen morphological trends are discussed with special reference to pollen size, shape and exine sculpturing.

Correlation between pollen morphology and pollination mechanisms in the Hydrocharitaceae.

The pollen morphology of 11 genera and 11 species of the Hydrocharitaceae and one species of the Najadaceae was studied using scanning and transmission electron microscopies, and the exine structures and sculptures are discussed in relation to pollination mechanisms and the molecular phylogeny. The pollen grains of the Hydrocharitaceae are spherical, inaperturate, and form monads or tetrads, while those of the Najadaceae are elliptical, inaperturate, and form monads. The entomophilous genera Egeria, Blyxa, Ottelia, Stratiotes, and Hydrocharis share pollen grains that have projections like spines or bacula. The anemophilous genus Limnobium has reticulate pollen grains. The hypohydrophilous genera Thalassia and Najas are characterized by pollen grains with reduced exine structures. The pollen-epihydrophilous genera Elodea and Hydrilla have tightly arranged small spinous pollen grains, and the male flower-epihydrophilous genera Enhalus and Vallisneria have reduced reticulate or gemmate exines. Character state reconstruction of the exine structures and sculptures using a molecular phylogenetic tree suggests that variation in the exine is generally correlated with the pollination mechanism; the selective pressures acting on the pollination mechanisms have reduced the exine structure in hypohydrophilous plants and resulted in various exine sculptures that are adapted to the different pollination mechanisms in entomophilous, anemophilous, and pollen-epihydrophilous plants.

The pollen morphology of Phyllanthus (Euphorbiaceae) section Choretropsis

The pollen grain morphology of the eight South American species of the genus Phyllanthus, subgenus Phyllanthus, section Choretropsis, endemic to Brazil, was investigated using light and scanning electron microscopy. The high homogeneity in pollen shape, as well as aperture number and configuration, allowed the definition of a basic pollen type for this section, viz. prolate spheroidal or subprolate, zonocolporate with 4–5 invaginated colpi, sexine reticulate. Two subtypes have been observed, based on pollen grain apertures and exine sculpture. The first subtype is characterized by straight and narrow colpi provided with costae, lalongate endoapertures and a reticulum of rectilineous muri as in P. choretroides and P. spartioides. The second subtype has wider colpi without costae, circular endoapertures and a reticulum with curvilineous muri as in P. flagelliformis, P. goianensis and P. scoparius, or curvilineous-rectilineous muri as in P. angustissimus, P. gladiatus and P. klotzschianus. It was demonstrated that the pollen shape and the number of colpi varied within and between some of the species. The results suggest that pollen grain morphology, in association with plant architecture and the presence of phylloclades, constitute additional evidence to delimit the species of the section Choretropsis and to further understand their evolutionary origin within the genus Phyllanthus. © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society, 2004, 144, 243–250.

Pollen structure, tetrad cohesion and pollen-connecting threads in Pseuduvaria (Annonaceae)

The structure of the pollen of 42 species of Pseuduvaria (Annonaceae) is described. The pollen is consistently inaperturate, isopolar and radially symmetrical. Four basic patterns of exine sculpturing are identified: rugulate, verrucate, scabrate and psilate. The exine stratification of one representative species, P. macrocarpa, is shown to be entirely ectexinal. The ectexine consists of a discontinuous outer tectal layer, a columellar infratectal layer, and an inner lamellar foliated foot layer; the intine is very thin and fibrillar. The pollen is invariably released as acalymmate tetrads, in which the tectum is absent from the proximal walls. The individual pollen grains within the tetrads are connected by crosswall cohesion, involving both exine and intine; this form of cohesion has not hitherto been reported in the Annonaceae. In addition, pollen grains of neighbouring tetrads are connected in two different ways, viz. short exine connections and non-sporopollenin pollen-connecting threads. Neither of these cohesion mechanisms has previously been reported for the genus. The function of the various forms of cohesion between pollen grains and tetrads in Pseuduvaria is discussed as a mechanism to enhance the efficiency of pollination by enabling the fertilization of multiple ovules following a single pollinator visit.

A new species of Gagea (Liliaceae) from Iran

Gagea iranica is described as a new species. The differences between this species and its closest ally are discussed. The pollen morphological analysis shows obvious the differences between the new species and its relative, i.e. G. bulbifera especially in the sculpturing of exine. The anatomy of leaf cross‐section also confirms the separation of this species from G. bulbifera. Beside the description of the new species, the scanning electron micrograph of the pollen grains, cross‐section of basal leaves, and illustrations of the new species are presented.