Pollen flow inPrimula veris (Primulaceae)

Observations on two natural and one artificial distylous populations ofPrimula veris in Britain revealed very high proportions of intramorph pollen on pin stigmas and moderate proportions of intermorph pollen on thrum stigmas. The average ratio of pin: thrum pollen production per flower was 2.4:1. Large amounts of pollen remained in dehisced anthers, perhaps reflecting low levels of pollinator activity. Population size and density had no clear effect on pollen flow patterns, which are asymmetrical for the two morphs.     

Systematics ofPrimula veris (Primulaceae)

Primarily, 50 characters taken from herbarium specimens, cultivated plants, and whole populations ofPrimula veris L. were critically evaluated. Only 24 characters were found to be suitable for taxonomic use. The geographical and multivariate analysis of about 1000 herbarium specimens from the whole area lead to a reduction of the number of subspecies. Only a less restricted subsp.veris (incl. subsp.canescens, subsp.inflata and probably including subsp.macrocalyx) and subsp.columnae (incl. subsp.suaveolens) can be distinguished considering the variability of characters within an individuum, under different culture conditions, and during the growth period. The status of the taxon macrocalyx cannot be cleared presently.     

Pollen morphology of JapaneseSymplocos (Symplocaceae)

The pollen morphology of all 23 Japanese species ofSymplocos (1 of subgenusEusymplocos, and 22 of subgenusHopea) was comprehensively studied using LM, SEM and TEM, and found to be classifiable into two types (Type I and II) primarily on the basis of wall structure. Type I, characterized by a thick tectum lacking a supratectal structure and reduced columellae, occurs in subgenusEusymplocos, while Type II, characterized by a thin tectum with a supratectal structure and generally distinct columellae, occurs in subgenusHopea. Resemblances in wall structure suggest a closer relationship of subgenusEusymplocos to subgenusMicrosymplocos as well as of subgenusHopea to subgenusEpigenia. This fact contradicts the earlier proposed infrageneric classification, and may require its revision. Within Type II, five subtypes are recognized primarily on the basis of sculpture combined with other pollen characters. Systematic value of sculpture (i.e., subtype), aperture morphology and “globules”, as well as certain species relationships based on those characters, are also discussed.     

Floral trait variation in fourCyclamen (Primulaceae) species

The purpose of this study is to examine floral trait variation between fourCyclamen species that show variation in their ability to reproduce in the absence of pollinators and in levels of inbreeding. Pollen and ovule production, pollen/ovule ratio, pollen volume, petal length and width, diameter of the corolla mouth, pistil and stamen length, and stigma-anther separation varied significantly between the four study species. Flower, pollen and ovule production, pollen volume and corolla size were generally highest inC. hederifolium, the species with the lowest level of inbreeding (mean F_is = 0.329), intermediate in both species with relatively high levels of pollinator-mediated inbreeding,C. repandum (mean F_is = 0.658) andC. creticum (mean F_is = 0.748), and lowest in the highly inbredC. balearicum (mean F_is = 0.930). The two species with the most different inbreeding coefficients,C. hederifolium andC. balearicum, had lower pollen-ovule ratios and shorter longevities of stigma receptivity and pollen viability thanC. creticum andC. repandum. These patterns of variation in floral traits are discussed in relation to the relatedness, pollination ecology and levels of inbreeding of the four species.     

Pollen morphology in theBoragineae (Boraginaceae) in relation to the taxonomy of the tribe

The results of a comparative survey on pollen morphology in theBoragineae by means of light, scanning and transmission electron microscopy are presented and discussed in relation to the taxonomy of the tribe. Multivariate analyses lead to the recognition of 15 pollen morphotypes for which a discriminant key is proposed. The discriminatory characters concern mainly the stereostructural and ultrastructural features of the grains, such as tectum sculpture and aperture morphology, while the number of apertures appears variable within genera and even single species. Seven out of the 12 investigated genera, as currently circumscribed, are matched by palynological data:Anchusella, Borago, Brunnera, Elizaldia, Lithodora, Symphytum andTrachystemon. On account of aperture shape,Lithodora is however closer to theLithospermeae than to theBoragineae. Other genera, and in particularNonea, show a wide variation in tectum ornamentation, shape of grains and number of apertures. Palynological data do not support a broad concept of the genusAnchusa, and point to the autonomy of the satellite generaHormuzakia, Gastrocotyle, Phyllocara, Pentaglottis andCynoglottis.     

Pollen morphology of the subtribe Cuspariinae (Rutaceae)

The neotropical subtribe Cuspariinae (Rutaceae) comprises as many as 26 genera and over 125 species. Pollen grains from 111 collections representing 71 species and 24 genera were examined by LM, SEM, and TEM. The pollen morphology of this subtribe is very diverse. Grains are mostly 3–6-aperturate and colporate, rarely porate (Spiranthera) or pantocolporate (Almeidea). Exine sculpturing is most commonly reticulate, sometimes perforate, foveolate-perforate, foveolate, foveolate-reticulate, reticulate, striate-reticulate, echinate, clavate, or baculate. The exine structure is columellate and tectate-perforate, columellate and semitectate, or intectate and is stratified into ektexine and endexine. The exine ofLeptothyrsa is distinctive in that the ektexine of the mesocolpium is longitudinally deeply ridged. The pollen ofHortia, characterized by a psilate exine with rare perforations, a very thick foot-layer, and reduced columellae, is unlike that of any member of the Cuspariinae and offers no support for the transfer of this genus from the Toddalioideae. The pollen data correlate with macromorphological characters and are taxonomically useful.     

Pollen grain morphology supports the taxonomical discrimination of Mediterranean oaks (Quercus,Fagaceae)

The exine architecture and some quantitative parameters (polar and equatorial axes and their ratio) of pollen grains allow a clear discrimination between groups of Mediterranean oak species. For the differentiation of species within groups only the quoted parameters prove useful.     

Pollen morphology ofVigna angularis (Leguminosae)

Pollen grains ofVigna angularis and its var.nipponensis are described with special reference to fine structure of the infratectum of the exine. They are 3-porate-operculate with granular infratectum and thin foot-layer. These features agree with those characterizing the genusVigna. In this species var.angularios and var.nipponensis are quite similar in pollen morphology. This supports the view that the two are closely related.     

Cyclamen (Primulaceae) in tropical Africa

Cyclamen somalense Thulin & Warfa, spec. nova, the first member of the genus known from tropical Africa, is described from the Al Miskat Mts in NE. Somalia. The new species is closely related to the E. MediterraneanC. persicum Mill. The disjunct Mediterranean element in the mountain flora of northern Somalia, to whichC. somalense belongs, is believed to be largely a relict of Tertiary origin.     

Pollen morphology and pollen-wall proteins (localization and enzymatic activity) inSesamothamnus lugardii (Pedaliaceae)

The pollen grains ofSesamothamnus lugardii Stapf (Pedaliaceae of subdesert regions of SE tropical Africa) are associated in acalymmate tetrads (cross wall cohesion), with a tectate and perforate exine and 8–12 colpi. The pollen wall consists of an ectexine with a complete, perforate and ample tectum, columellated infratectum and clearly interrupted and fragmented foot layer. The endexine is built of scanty lamellae and granules. The intine is bistratificate, with a homogeneous, fibrillate layer (endintine or intine-2) and a heterogeneous, more lax and channeled layer (exintine or intine-1). Test for glycoprotein is particularly positive in the homogeneous internal intine and channels of external intine. On the other hand acid phosphatase has been localized in the exine and channeled external intine layers. These observations confirm the general interpretation of the distribution of wall compounds.     

Pollen grain wall structure ofCaytonanthus arberi (Caytoniales)

The pollen grain wall structure ofCaytonanthus arberi was studied with SEM and TEM. The monosulcate, bisaccate pollen grain of this taxon has an alveolar wall structure that is more like that found in saccate Conifers than primitive Angiosperms. Pollen grain morphology does not support a Caytonialean ancestry for the Angiosperms.     

Pollen morphology and ultrastructure of selected species of Magnoliaceae

The pollen morphology and ultrastructure of 20 species, representing eight genera of the Magnoliaceae are described based on observations with light, scanning and transmission electron microscopy. The family represents a homogeneous group from a pollen morphological point of view. The pollen grains are boat-shaped with a single elongate aperture on the distal face. The tectum is usually microperforate, rarely slightly or coarsely rugulose. Columellae are often irregular, but well-developed columellae do occur in some taxa. The endexine is distinct in 14 species, but difficult to discern in the genera Parakmeria, Kmeria and Tsoongiodendron. Within the aperture zone the exine elements are reduced to a thin foot layer. The intine has three layers with many vesicular-fibrillar components and tubular extensions in intine 1. The symmetry of the pollen grains, shape, type of aperture and ultrastructure of the intine show a remarkable uniformity in the family. Nevertheless there is variety in pollen size, ornamentation and the ultrastructure of the exine. The pollen of Magnoliaceae is an example of an early trend of specialization, and supports the view that Magnoliaceae are not one of the earliest lines in the phylogeny of flowering plants.     

Pollen morphology and functional dioecy inSolanum (Solanaceae)

Dioecy has evolved independently several times in the large, mostly tropical genusSolanum. In all cases of dioecy inSolanum functionally male flowers have normal anthers, normal pollen and reduced stigmas while functionally female flowers have stigmas and anthers that appear normal but contain non-functional, usually inaperturate pollen. The inaperturate pollen has living cytoplasm, but apparently never germinates and it has been hypothesised that the pollen in these functionally female flowers is retained as a pollinator reward. Pollen morphology is compared in twelve of the thirteen known dioecious species ofSolanum, and some stages in the the development of inaperturate pollen in the anthers of functionally female flowers ofSolanum confertiseriatum of Western Ecuador are examined. Observations on the development and morphology of inaperturate pollen in functionally female flowers ofSolanum are related to hypotheses about the evolution of dioecy in the genus.     

Pollen morphology ofLactoridaceae

The pollen wall ultrastructure of the primitive AngiospermLactoris fernandeziana Phil. (Lactoridaceae) is described. The monosulcate aperture, granular wall structure and sacci (all primitive features) suggest placement of this family in theMagnoliales. Pollen ofLactoris is compared to fossil dispersed pollen from the Lower and lower-Upper Cretaceous. The fossil pollen shares characteristics which are restricted to theLactoridaceae suggesting that this family was present during the early Cretaceous.     

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.     

Cytological studies inCyclamen subg.Cyclamen (Primulaceae)

Although theCyclamen subg.Cyclamen spp. are morphologically variable, previous studies suggest a superficial cytological uniformity. New chromosome numbers and an indication of karyotypic instability are reported inC. hederifolium andC. africanum that reveal that the cytology of the subgenus is more complicated than previous accounts suggest. The possible significance of these phenomena is discussed. The diploid status ofC. purpurascens has been confirmed and a distinction between the three diploid karyotypes has been described. The cytological variation may help to explain the well documented morphological variation exhibited in these species.     

Pollen morphology of some species belonging to Codonoprasum and Allium sections of Allium (Liliaceae-Alliaceae) genus

Pollen morphology of 14 Allium L. species grown in Turkey, that belong to the sections Codonoprasum and Allium, were investigated under LM (light microscopy) and by SEM (scanning electron microscopy). However, the pollens of 5 species were investigated under TEM (transmission electron microscopy). Detailed pollen morphological characteristics are given for Allium in the family on the basis of the results presented here together with data from the literature. The genera Allium homogeneous in both aperture type and exine ornamentation. It is suggested that some palynological characters, such as aperture type and the presence of an operculum, could be of taxonomic value at the section level.     

Pollen morphology of some <Emphasis Type="Italic">Paronychia</Emphasis> species (Caryophyllaceae) from Turkey

The Pollen morphology of 13 taxa 11 of which are endemics belonging to Paronychia Miller (Caryophyllaceae) viz., P. agryloba, P. angorensis, P. arabica subsp. euphratica, P. carica, P. cataonica, P. chinonea, P. condensata, P. davisii, P. dudleyi, P. galatica, P. kurdica subsp. kurdica, P. kurdica subsp. montis-munzur and P. mughlaei from Turkey has been investigated by light (LM) and scanning electron microscopy (SEM). LM observations show that pollen grains are usually radially symetrical, isopolar, pantoporate, polygonal (6-gonal) or polygonal-spheroidal. Tectum is psilate or punctate. Tectal surface sparsely-densely spinulose. The numbers of pores are between 6 and 12. On the basis of pollen sizes, P. davisii was the biggest pollen type (23.45 μm) and P. kurdica subsp. kurdica (16.2 μm) was the smallest pollen types. According to exine sculpturing, pollen size and spinule numbers per 1 μm², three pollen types were distinguished.