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.     

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.     

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

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

A first molecular phylogenetic analysis of Passiflora (Passifloraceae)

Passiflora, a genus with more than 400 species, exhibits a high diversity of floral and vegetative structures and a complex taxonomy, which includes 23 subgenera and many sections and series. To better understand Passiflora's variability and interspecific relationships, the phylogeny of 61 species, classified in 11 of 23 suggested subgenera, was investigated. Three molecular markers were used, the nuclear ribosomal internal transcribed spacers (nrITS), the plastid trnL-trnF spacer regions (～1000 bp), and the rps4 plastid gene (～570 bp). Three major clades were highly supported, independent of the marker and phylogenetic method used; one included the subgenera Distephana, Dysosmia, Dysosmioides, Passiflora, and Tacsonioides, a second, the subgenera Adopogyne, Decaloba, Murucuja, and Pseudomurucuja, and a third, the subgenus Astrophea. We call these the Passiflora, Decaloba, and Astrophea clades, respectively. The position of subgenus Deidamioides is undefined. The monophyly of Passiflora could not be statistically corroborated, and the relationships among the major clades and of these clades with the related genera remain unresolved. Our results indicate that a reevaluation of the monophyly of Passiflora and its infrageneric classification is necessary.     

Pollen morphology and systematics of palaeotropical Phyllanthus and related genera of subtribe Phyllanthinae (Euphorbiaceae)

The observations of pollen from 27 species of subtribe Phyllanthinae using scanning electron microscopy reveal considerable morphological diversity in palaeotropical Phyllanthus and the related palaeotropical genera Breynia, Glochidion, and Sauropus. The tribe appears to be monophyletic, but the pollen morphology does not support the monophyly of Phyllanthus or Sauropus. Within Phyllanthus, the pollen characters suggest a close relationship between the subgenera Emblica and Phyllanthodendron. They also reveal a surprising morphological congruence between the pollen grains of section Ceramanthus (subgenus Isocladus) and those of subgenus Eriococcus, although it is not clear whether this similarity is homoplastic. The presence of diploporate colpi is a synapomorphy uniting Breynia and Sauropus, but may be homoplastic in Phyllanthus. The affinities suggested by the morphological features of the pollen in the Phyllanthinae are concordant with recent molecular phylogenies. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 157 , 591–608.     

Phylogeny of the Afro-Madagascan Aristea (Iridaceae) revisited in the light of new data on pollen morphology

Scanning and electron microscopic studies of the pollen grains of several species of the sub-Saharan African and Madagascan genus Aristea of c . 50 species, supplement data from an earlier study and enable us to include these species in a phylogenetic analysis. TEM examination of a range of pollen grains of representative pollen types in Aristea makes it possible to reinterpret past SEM results so that apertures covered with exine masses and previously called sulculate, are now seen to be either zonasulculate or dizonasulculate. Revised and expanded data are combined in a matrix together with new data for seed morphology in the genus, which like the capsules is remarkably diverse, including angular seeds with reticulate sculpturing, lamellate or triangular-columnar seeds with smooth or reticulate surfaces and with smooth or papillate or areolate margins. This new phylogenetic analysis suggests that Aristea should remain treated as comprising three subgenera. In subgenus Eucapsulares we add a new section Latifolieae for A. latifolia , which seems an isolated relic restricted to the mountains of the Cape Region of South Africa, an area of winter rainfall. Species with similar unspecialized capsule and seed morphology occur only in eastern south and tropical Africa and Madagascar, but they have derived pollen morphology whereas the pollen of A. latifolia is plesiomorphic. This species appears to be the closest living ancestor of the genus. In subgenus Aristea we continue to recognize three sections, sect. Racemosae , sect. Singulares and sect. Aristea. Nesting of subgenus Pseudaristea within section Racemosae of subgenus Aristea is probably an artefact of the analysis and does not receive bootstrap support, and hence we continue to recognize this group of species at subgeneric rank.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 41–68.     

Palynotaxonomy of Brazilian species of Polygala subgenus Hebeclada

This study used pollen morphology to address taxonomic controversies related to several species belonging to subgenus Hebeclada of the genus Polygala (Polygalaceae). According to the last traditionally accepted revision of this subgenus, it comprises 40 species. Nevertheless, a recent taxonomic treatment applying more comprehensive criteria reduced this number to only nine species. Our work focused on 15 traditionally accepted species that occur in Brazil, fourteen of which have been considered as only six species in this recent taxonomic study. Pollen grains from floral buds at pre‐anthesis were collected from herbarium specimens and analysed using both visible light and scanning electron microscopy. Most of the traditionally accepted species were distinguished by different combinations of several pollen‐related features, in particular colpi number (13 or 15), pollen size and shape, and endoaperture type (endocingulate or not) and arrangement (parallel or sinuous). The species accepted in the recent taxonomic treatment could not be discriminated by pollen characters. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 157 , 609–619.     

A palynotaxonomic study of the genus Filipendula (Rosaceae)

Pollen grains from 15 species (18 taxa) of the genus Filipendula were examined with light and scan-ning electron microscopy. It was revealed that the pollen grains are isopolar, tricolporate, with scabrate or scabrate-microechinate surface. The pollen morphology was compared with the conventional classification sys-tems of the genus by different authors, and supported Shimizu's system (1961), in which the genus was divided into three subgenera. The monotypic subgen. Hypogyna is characterized by pollen lacking fastigium and thickened costae colpi. The other monotypic subgen. Filipendula differs from others by pollen having larger grain, larger pore size, longitudinally elliptic fastigium and thickened costae colpi. The largest subgen. Ulmaria is distinguished by pollen having rounded or latitudinally elliptic fastigium and thickened costae colpi. Sectional classification was not supported by the pollen morphology due to insufficient variability.     

Morphological and pollen differentiation in Solanum cardiophyllum ssp. cardiophyllum and S. cardiophyllum ssp. ehrenbergii

A multivariate analysis to differentiate morphologically the populations of wild potatoes Solanum cardiophyllum ssp. cardiophyllum and S. cardiophyllum ssp. ehrenbergii was carried out. An analysis of the morphology and the viability of pollen of these potato populations was also made. The results of the morphometric analysis indicate that both subspecies are phenetically different. The pollen grain shape and size in ssp. cardiophyllum are different in northern and southern populations. Pollen diameter is significantly different between subspecies. Based on these results we propose that these taxa should be considered as two separate species.  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 140 , 415–426.     

Development and ultrastructure of the megagametophyte in Passiflora caerulea L. (Passifloraceae)

Megasporogenesis and megagametogenesis of Passiflora caerulea L. were studied using light and transmission electron microscopy. The archesporial tissue is generally formed by one cell. The megaspore mother cell gives rise to a linear tetrad of megaspores. The chalazal megaspore is the functional one, and originates a Polygonum -type female gametophyte. The antipodals are ephemeral. Abundant starch is found in the nucellar cells, specially the ones adjacent to the megagametophyte. The two synergids show ultrastructural differences, involving the filiform apparatus, the nucleolus and the endoplasmic reticulum; these differences suggest a functional differentiation, probably related to the reception of the pollen tube. This is the first report in angiosperms of substantial morphological differences between the two synergids.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 73–81.     

Relationships, classification and evolution of Scleranthus (Caryophyllaceae) as inferred from analysis of morphological characters

Study of floral anatomy, micromorphology, palynology and onotogeny has revealed new characters for phylogenetic analysis in the genus Scleranthus . Cladistic analysis of these characters, along with those previously available, suggests that the genus consists of Eurasian/Mediterranean and Australasian sister clades. Gynoecial morphology and development are closely similar in all species, suggesting the genus is monophyletic despite its disjunct northern and southern hemisphere distribution. Variation in pollen:ovule ratios and their implications for the evolution of Scleranthus species are also discussed and it is concluded that a range of breeding strategies intermediate between autogamy and xenogamy exists in the genus. Single-stamened species of Scleranthus are likely to be obligate autogams, despite their comparatively high pollen:ovule ratios in relation to autogamic species of other genera.  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 140 , 15–29.     

Phylogenetic relationships among Passiflora species based on the glutamine synthetase nuclear gene expressed in chloroplast (ncpGS)

This paper presents the first molecular phylogeny of the genus Passiflora encompassing almost all sections of this large genus. The nuclear-encoded chloroplast-expressed glutamine synthetase gene (ncpGS) was used to examine the relationships among Passiflora species (passionflowers), which was then compared with the new classification proposed by Feuillet and MacDougal. The resulting Bayesian, likelihood, and parsimony trees are congruent and well supported. The 90 Passiflora species examined apparently split into eight main subgenera: Plectostemma, Granadilla, Astrophea, Deidamioides, Polyanthea, Dysosmia, Tetrapathea, and Tryphostemmatoides. These results are in overall agreement with the Feuillet and MacDougal's classification but here we propose that three additional subgenera, Polyanthea, Dysosmia, and Tetrapathea, should be maintained. We observe a striking overall correlation between the phylogenetic position of the different species and their chromosome number. The first clade contains the arborescent species of the subgenus Astrophea, with n=12. The second clade, subgenus Plectostemma, includes species from four subgenera of Killip's classification with n=6 chromosomes. The last clade, subgenus Granadilla, includes species of seven old subgenera with n=9. Subgenus Dysosmia, with a variable chromosome number of n=9-11, is considered here as a separate subgenus closely related to the subgenus Granadilla.     

Pollen morphology of Dioscorea (Dioscoreaceae) and its relation to systematics

This paper adds new data on the pollen and orbicule morphology of 61 Dioscorea L. (Dioscoreaceae) species to the survey of Schols et al . (2001). The results indicate that pollen characters may be significant in infrageneric systematics in Dioscorea . Pollen and orbicule characters are described based on observations with light microscopy, and scanning and transmission electron microscopy, and are critically evaluated and discussed in the context of existing hypotheses of systematic relationships within the genus. Pollen is mostly disulculate (sometimes monosulcate) with a perforate, microreticulate, striate, gemmate, rugulate, or cerebroid perforate sexine. The basal section Stenophora is one of the few sections with monosulcate pollen. Brachyandra , Cardiocapsa , and Seriflorae , three Malagasy sections, are characterized by striate pollen. Pollen morphology strongly supports section Enantiophyllum as a monophyletic group. The correlation between pollen size and tuber type, as suggested previously by P. Su (1987), is confirmed by our data. As found in our earlier survey, orbicules in Dioscorea are mostly spherical with a smooth or spinulose surface.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 143 , 375–390.     

Systematic relevance of pollen and orbicule characters in the tribe Hillieae (Rubiaceae)

Pollen and orbicule morphology of 26 species in the tribe Hillieae is described based on observations by light, scanning and transmission electron microscopy. Pollen and orbicule characters are critically evaluated and discussed in the context of existing hypotheses of systematic relationships within the tribe. Pollen is 3-zonocolporate with a perforate, microreticulate, reticulate or eutectate sexine. In the two species of Blepharidium , however, the pollen has one, four or five apertures. These pollen morphological data were incorporated into an existing macromorphological matrix of the group and cladistically analysed. The resulting phylogenies indicate that it may be appropriate to reduce Cosmibuena to a subgenus of the genus Hillia , while Blepharidium should be removed from Hillieae because of the deviating pollen type that is unique to the Rubiaceae. All species investigated produce orbicules, which are mostly spherical and possess an electron-lucent core that is sometimes characteristically flattened.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 303−321.     

Pollen morphology in Psychotria (Rubiaceae, Rubioideae, Psychotrieae) and its taxonomic significance. A preliminary survey

The pollen morphology in 168 species of Psychotria (Rubiaceae, Rubiodeae, Psychotrieae) has been investigated using light microscopy and, for 61 of the speices, scanning electron microscopy. Transmission electron microscopical studies have been carried out for seven of the species. Psychorria is very heterogeneoous pollen morphologically and pollen grain characteristics cannot be used for the delimination of the basis of aperture morphology, thickness of exine, size of lumina, muri, columellae and bacula, and sculpture. A key to the identificantion of the pollen types is presented and all types are issstrated. The pollen grains in Psychotria are usually 3–to 5colporte, 3-to 5-colpate or inapertuarate, rarely 2–4-or 5-porate, and have an exine that vanes widely in thickness. The sexine is reticulate, microreticulate, tectate-perforate, rugulate or intectate, and smooth or sculptured. Exine morphology presents important characters for the taxonomic subdivision of Psychotria . Previous intrageneric classifications are in part supported by pollen morphology, but contradictions between this and other sets of charactes, such as inflorescence features. are common.     

A survey of androconial organs in the Riodinidae (Lepidoptera)

A comprehensive survey of the occurrence and morphology of alar, abdominal and appendage androconial organs in the Riodinidae is presented based on light microscopy and scanning electron microscopy. Although historically poorly studied, the group actually possesses among the greatest diversity of androconial organs in the butterflies, including coremata, reported here for the first time outside the Lycaenidae and Nymphalidae, and hindleg hairpencils, reported here for the first time in the true butterflies. Twenty-five percent of riodinid species are reported to have androconial organs. The mode of function of these organs and their role in courtship is discussed where known, based on field observations. A number of taxonomic changes are made at the tribal, generic and species level, predominantly in the Symmachiini, based on the occurrence and structure of androconia.  © 2002 The Linnean Society of London, Zoological Journal of the Linnean Society , 2002, 136 , 171–197.     

Taxonomic significance of pollen types in the Guyana Highland-centred composite genera of Mutisioideae (Asteraceae)

The Guyana Highland-centred genera, or Stenopadus group, are a complex of species that belong to the tribes Mutisieae and Stifftieae of Asteraceae. The pollen morphologies of 29 species, from 12 of 13 genera of this complex, are described and illustrated using light and scanning electron microscopy. The exine sculpture and structure are highly significant. Four exine types, previously characterized, were distinguished: Gongylolepis , Wunderlichia , Mutisia , and Stenopadus . The characterization of the Stenopadus exine type is enlarged here. These exine types led to the recognition of four well-defined pollen types, whereas the spine length and exine thickness characterized six subtypes. Pollen types circumscribe genera or groups of genera, and some subtypes distinguish species. The pollen morphology within the complex is discussed in relation to the rest of Mutisioideae and other palynologically allied tribes of Cichorioideae. There is little correlation between pollen types and tribes; only the Stenopadus exine type is exclusive to the Stifftieae tribe. The remaining types are shared by the two tribes of the complex. Pollen morphology supports the hypothesis that this group of genera is close to the Gochnatia complex and the Cardueae tribe.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 156 , 327–340.     

The intersectional hybrid between Weigela hortensis and W. maximowiczii (Caprifoliaceae)

Morphologically intermediate plants between Weigela hortensis (Siebold & Zucc.) K.Koch and W. maximowiczii (S.Moore) Rehder have been found in Miyagi and Yamagata Pref., northern Japan. Quantitative character analyses of flowers, pollen stainability and molecular analyses indicated that the intermediate plants were hybrids of those two species. This is the first record of an intersectional hybrid with W. maximowiczii (sect. Weigelastrum ) as one of the parent species. The morphological differences among hybrid individuals imply the possibility of backcrosses or formation of second or later generations of hybrids, although those may be quite rare because of a low frequency of viable pollen grains. Causes of hybridization between two distantly-related species in Weigela are discussed. © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 138 , 369–380.     

A preliminary palynological characterization of Spanish thyme honeys

Pollen was analysed in 25 thyme honey samples from Spain. The honey samples were provided by professional beekeepers, and pollen was obtained by centrifugation. A minimum of 8% of Thymus sp. pollen is considered sufficient to typify a honey as unifloral when considering pollen grains from anemophilous and nectarless plants. The quantitative analysis showed that nectar is the main honey source in the samples studied. The qualitative analysis of the samples revealed the presence of 53 taxa belonging to 27 families. The Spanish thyme honeys of the studied region are characterized by their medium to high numbers of grains of pollen (NGP; mean = 155 000) and their medium to high content of honeydew indicator elements (HDE; mean = 8300). Genista type (present in 100% of the samples), Echium plantagineum and Reseda luteola (90%), Eucalyptus type (80%), Calendula type and Olea europaea (75%), and Cistus monspeliensis (70%) may be mentioned among the characteristic accompanying species of this honey type.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 323–330.