Exine Sculpture Research Articles

Morphology, anatomy, palynology and nutlet micromorphology of Salvia macrochlamys (Labiatae) in Turkey

Salvia macrochlamys Boiss. & Kotschy, which belongs to sect. Salvia Hedge, is a perennial herb usually growing on rocky limestone slopes in eastern Anatolia. In this study, the anatomical features of the root, the stem, the leaf and the petiole, as well as micromorphological characteristics of the pollen and the nutlet of this species have been investigated using Scanning Electron Microscopy (SEM). Moreover, its emended and expanded description, phenology, current distribution and ecology are also given. Anatomical characters such as the number of ray lines in the root, the distance between vascular bundles in the stem, the structure of mesophyll in the leaf and the structure of vascular bundles in the petiole have been found to have taxonomic value. The pollen grains are hexacolpate, radially symmetrical, isopolar and oblate-spheroidal. Their exine sculpturing is bireticulate and perforate. The nutlets are rounded-trigonous in transverse sections, broadly ovate to rotund in shape, light brown, glabrous and slightly rough to protuberances. This species often grows in habitats in which the main soil type is sandy-clayish with low organic content (1.32 ± 1.06%) and slightly alkaline (pH 7.75 ± 0.25). The amount of CaCO3 is 0.94% to 34.91%. The contents of P and K are 8.68 ± 0.96 and 110.12 ± 4.86 ppm, respectively.

Pollen Morphology and Viability of Elaeagnus umbellata

Different methods were applied to specimen preparation of Elaeagnus umbellata pollens for SEM observation.Results indicated that the natural drying pollen morphology of E.umbellata changed seriously,but pollen shape maintained well by the fixation and dehydration.The pollen grains of E.umbellata are subspheroid in equatorial view,triangle-boll and 3-colporate in polar view,and the exine sculpture is cerebroid.Viability of the pollen was measured by I2-KI staining in different time after anthesis.Results showed that the mean pollen viability is high in inchoate anthesis,and declines after sharply 36 hours,but a few pollen grains are still viable at the end of anthesis.

A Method for Image Analysis of the Pollen Exine Sculpture

A Method for Image Analysis of the Pollen Exine Sculpture

Pollen morphology of the genus Fritillaria L. (Liliaceae) in Turkey

Pollen grains of 39 taxa of the genus Fritillaria L. in Turkey were examined by light and scanning electron microscopy. Detailed pollen morphological characteristics are given for these taxa. Our investigation shows that the sculpturing of the exine provides valuable characters for separating species. In particular, sculpturing of the exine at the proximal face turned out to be taxonomically important. Six types of ornamentation were determined: reticulate, reticulate-perforate, suprareticulate, rugulate-reticulate, psilate-perforate, and perforate. On the basis of exine sculpturing, the sulcus membrane, and the apex sulcus, 5 main pollen types are recognised.

Evaluation of pollen morphology as a taxonomic character for generic delimitation in Scilla s.l. (Hyacinthaceae)

Scilla L. s.l. (Hyacinthaceae) comprises about 100 species distributed in south Europe, the Mediterranean region, and central and western Asia with 10 species reported from Iran.However, according to recent studies based on molecular data Scilla s.l. is not monophyletic and should be divided into several smaller genera, i.e. Fessia Speta, Othocallis Salisb., Pfosseria Speta, Prospero Salisb., Scilla s.s. and Zagrosia Speta.In the present study the pollen grains of 13 species representing six segregate genera within Scilla s.l. were studied to evaluate the taxonomic value of pollen characters for generic delimitation. Pollen grains of all examined species were found to be monosulcate, prolate or sub‐prolate and heteropolar. Three different types of exine sculpturing were recognized: fossulate, perforate–reticulate and perforate.In Prospero autumnale (=Scilla autumnalis) pollen exine sculpturing is fossulate. In Othocallis armena, O. mischtschenkoana, O. rosenii and O. siberica (=Scilla armena, S. mischtschenkoana, S. rosenii and S. siberica) exine sculpturing is perforate–reticulate with mainly large perforations surrounded by smaller ones. In Fessia gorganica, F. greilhuberi, F. hohenakeri, F. khorassanica and F. raewskiana (=S. gorganica, S. greilhuberi, S. hohenakeri, S. khorassanica and S. raewskiana) the exine is perforate with rather uniform perforation. Zagrosia persica (=S. persica) has the same exine type as Fessia spp. In Pfosseria, the exine is perforate with linear and circular perforations. Scilla s.s. has a perforate exine, but the perforations are not uniform and their size and shape are variable.Our results are generally congruent with the circumscription of the new genera previously included in Scilla s.l. and show that pollen exine morphology is useful as an additional taxonomic character for the delimitation these segregate genera.

The Pollen Ultrastructure of Williamsoniella coronata Thomas (Bennettitales) from the Bajocian of Yorkshire

The exine ultrastructure of Williamsoniella coronata Thomas from the Bajocian of Yorkshire (United Kingdom) was investigated with light, scanning electron, and transmission electron microscopy. The pollen averages 16.5 μm along its short axis and 24.5 μm along its long axis and is monosulcate, and the nonapertural sculpturing is distinctly verrucate. The pollen wall is homogeneous, and the sulcus membrane is composed of thin exine with scattered small granules. The pollen grains differ in exine sculpturing and pollen wall ultrastructure from pollen grains of the bennettitalean taxa Cycadeoidea dacotensis (MacBride) Ward and Leguminanthus siliquosis (Leuthardt) Kraeusel. They are similar to dispersed pollen grains of Granamonocolpites luisae Herbst from the Triassic Chinle Formation of the United States, supporting the bennettitalean affinity of these dispersed pollen grains. The Bennettitales are palynologically characterized by monosulcate “boat‐shaped” pollen with a homogeneous or granular pollen wall ultrastructure.

Palynological data on Illiciaceae and Schisandraceae confirm phylogenetic relationships within these two basally-branching angiosperm families

Illiciaceae and Schisandraceae, together with other members of Austrobaileyales have been identified as one of the earliest diverging lineages of angiosperms, within the ANITA grade. The specialized Illiciaceae and Schisandraceae comprise a clade defined by apomorphic characters including pollen grains with three or six colpate apertures. In both these families, pollen apertures and exine sculpture were found to be very informative when considered in the context of recent understanding of evolutionary patterns. In the current study, pollen grains of 21 taxa from Illiciaceae and Schisandraceae were investigated. These data, together with palynological data for taxa previously studied, were mapped into recent molecular phylogenetic trees to re-evaluate the existing classification and phylogenetic relationships in the two families. Palynological data were found to be relatively congruent with recent molecular phylogenies, while traditional delimitations of infra-generic taxa were somewhat conflicting and did not reflect phylogeny and evolution. The evolution of pollen morphology in the two families, together with other members of Austrobaileyales, is discussed in comparison with the molecular phylogenies.

A quantitative evaluation of the distylous syndrome in Sebaea grandis (Gentianaceae)

Distyly is a rare polymorphism characterized by short-styled [S] and long-styled [L] floral morphs. It has been hypothesized to reduce the gender conflict inherent in hermaphrodite flowers. In particular, the reciprocal arrangement of male and female parts promotes precise pollen transfer between morphs, and the heteromorphic incompatibility system that is associated with distyly can eliminate uniparental inbreeding depression. We studied the syndrome of floral traits associated with distyly in Sebaea grandis, a perennial herb common in South African grasslands. Flowers have the reciprocal reproductive organ arrangement characteristic of the distylous syndrome, and L- and S-morphs occurred at equal frequencies in the two populations that were studied. S- and L-morph flowers did not differ significantly in size, although the S-morph produced larger pollen grains and pollen exine sculpturing differed between the two morphs. Approximately 80% of the pollen deposited on the stigmas of either morph was legitimate (intermorph), suggesting that distyly in this species promotes cross-pollination. A controlled pollination experiment suggests that S. grandis possesses a heteromophic incompatibility system: no fruits were produced following intramorph pollinations, whereas intermorph pollinations resulted in 70% of flowers setting fruit. Fluorescence microscopy revealed clear differences among morphs in the site of incompatibility. Intramorph pollen grains did not grow beyond the stigmatic surface of the L-morph, and growth was arrested in the stylar canal of the S-morph, while intermorph pollen grains germinated on the stigmatic surface, grew through the stylar canal and entered the ovary. This study demonstrates that S. grandis displays the morphological traits and genetically controlled incompatibility system associated with heterostylous plants.

Pollen morphology of the genusCornukaempferia(Zingiberaceae) in Thailand

Cornukaempferia is a recently described genus of Zingiberaceae which only occurs in Thailand as a rare genus with limited geographical distribution. Only three species have been described so far, including a recently described new species, C. larsenii. These three species are morphologically very similar and additional data on other biological aspects are useful for the elucidation of their relationship. Pollen morphology of all three species of genus Cornukaempferia has been studied by light microscopy and scanning electron microscopy. The pollen grains are monad, spherical, inaperturate. The exine sculpture is echinate with psilate between the spines for C. aurantiflora and C. longipetiolata, or echinate with regulate between the spines for C. larsenii. This observation helps support the taxonomic status of C. larsenii.

Pollen morphology ofRhododendronsubgen.Tsutsusiand its systematic implications

Eighty-four pollen samples were obtained for 80 taxa, of which, 13 species and one variety are from sect. Brachycalyx Sweet, 58 species and two varieties from sect. Tsutsusi Sweet, and six species from subgen. Pentanthera (G. Don) Pojarkova, respectively. Pollen morphology of all samples was observed using LM and SEM. Pollen grains are revealed to be spheroidal and tetrahedral with tricolporate apertures. Pollen sizes of subgen. Tsutsusi (Sweet) Pojarkova range from 37.67 μm to 61.06 μm, and the exine sculptures are more or less compactly granulated. Pollen sizes are significantly different between sect. Brachycalyx and sect. Tsutsusi of subgen. Tsutsusi. Rhododendron tashiroi Maxim. of sect. Tsusiopsis Sleumer shows a close affinity to sect. Brachycalyx. Pollen size and exine are consistent with general morphology in differentiating species in sect. Tsutsusi. Rhododendron huadingense B. Y. Ding & Y. Y. Fang, once placed as a member of sect. Brachycalyx, should be considered as a species in subgen. Pentanthera.

Pollen morphology of some Gypsophila L. (Caryophyllaceae) species and its taxonomic value

Pollen morphology of 12 taxa (6 of them endemic) that belong to the genus Gypsophila L. were investigated using light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Differences in pollen morphology between these taxa were determined based on palynological studies. Pollen grains are spheroidal and polyporate. The exine structure is tectate, but that of G. sphaerocephala var. sphaerocephala is intectate. The exine sculpture is granulate-microechinate-microperforate, but that of G. sphaerocephala var. sphaerocephala displays clavate-microechinate ornamentation. The operculum exists in the form of scattered pieces in G. curvifolia, while it exists as a whole in the other taxa. G. perfoliata var. perfoliata has the largest pollen grain diameter, whereas G. tubulosa has the smallest. The exine consists of 2 parts; the upper part is the thick ectexine and the lower part is the thin endexine. The endexine is thin and continuous.

Pollen and Seed Morphology of the Genus Hesperis L. (Brassicaceae) in Turkey

Pollen and seed morphology were examined in 35 specimens representing 25 Turkish species of the taxonomically complex genus Hesperis L. by light and scanning electron microscopes. Three main types and 2 subtypes were recognized based on the seed coat surface, pollen shape, and exine sculpturing. The seed coat ornamentation of Type I was ocellate, and pollen shape was oblate-spheroidal. While Type II was represented by reticulate seed coat and prolate-spheroidal pollen shape, Type III had tuberculate seed coat. This study revealed that both palynological and seed morphological characters are of significant importance in the taxonomy of the genus.

Palynological survey of subtribe Pithecocteniinae (Bignonieae, Bignoniaceae)

The pollen morphology of subtribe Pithecocteniinae was reviewed. Thirty species of the six genera currently recognized, namely Amphilophium, Distictis, Distictella, Glaziovia, Haplolophium and Pithecoctenium, were considered. All the species surveyed fell into one of the two pollen groups: (1) inaperturate, spheroid pollen; and (2) stephanocolpate, prolate pollen. The former group included the studied species of Distictis, Distictella and Pithecoctenium, the latter species of Amphilophium, Glaziovia and Haplolophium. The variation of exine sculpture and thickness did not show any taxonomic relationships. An argument for considering pollen features, together with other morphological characters, to elucidate monophyletic units within Pithecocteniinae is presented. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 159, 155–162.

Morphology and variability of pollen of the genus Spiraea L. (Rosaceae) in Siberia and the Far East

Pollen of 12 species of the genus Spirea L. growing in different regions of Siberia and the Far East was investigated. The ultrasculpture of pollen grains is described. On the basis of aperture morphology and exine sculpture, pollen grains are typified, with key indices given for their identification. The species of the Spiraria section are distinguished by large grains. Pollen grains of S. media and S. alpina considerably vary in size. The level of natural polymorphism of palynological indices has been established.

Pollen morphology of the genus Skimmia (Rutaceae) and its taxonomic implications

Pollen morphology of the genus Skimmia was studied. Of six species of the genus, five species were investigated by light microscopy and scanning electron microscopy. Pollen grains of Skimmia had striate to striate-reticulate sculpture and variable aperture number (3-7), and these characters differed from even the phylogenetically closest relatives such as Dictamnus and Casimiroa which have 3-colporate pollen grains with reticulate exine. In Skimmia laureola, pollen dimorphism is suggested in the aperture number in accordance with the floral system. Pollen grains of Skimmia japonica, a morphologically very variable species, were extensively surveyed covering its whole distribution area. The grains were also striate to striate-reticulate, and the exine sculpture was not different between varieties. However, the aperture number of S. japonica showed a geographical variation ranging from 4 to 6; in Sakhalin, Hokkaido, most part of Honshu and Taiwan, grains with 4-5 apertures were dominant, while in the southern part of Japan, including the Ryukyu Islands and the Izu Islands, those with 5-6 apertures were common.

Pollen morphology of Patrinieae Hock (Valerianaceae)

Pollen grains of 17 taxa (14 species with two additional subspecies and one variety) of genera Patrinia Juss. and Nardostachys DC. in tribe Patrinieae (Valerianaceae) were studied using light microscope, scanning electron microscope, and transmission electron microscope. Pollen grains are medium (37.41 × 43.60 ㎛ - 45.65× 48.50 ㎛) to large (54.88 × 59.41 ㎛ - 61.70 × 71.00 ㎛) in size, tricolpate (rarely tetracolpate) with the characteristic halo surrounding the aperture. In equatorial view, the pollen is oblate to subprolate, and in polar view, it is mostly circular or rarely 3-lobed. Two major pollen types are recognized on the basis of exine sculpturing patterns; Type I: Exine is composed of echinae together with sparse or dense microechinae, and verrucae shallow or rarely absent (Nardostachys and sections Paleopatrinia, and Monanadropatrinia of Patirinia). - Type II: Exine is composed of massive echinae together with dense microechinae, and prominent verrucae (section Centrotrinia of Patrinia). In TEM sections, columellae are extended from the footlayer into verrucae, and exine thickness is uniform at the pole and equator. Additionally, the infrageneric classification systems of the Patrinieae were evaluated on the basis of the present data.

Comparative pollen morphology in the early‐divergent angiosperm family Hydatellaceae reveals variation at the infraspecific level

The small aquatic family Hydatellaceae was recently assigned to the early‐divergent angiosperm order Nymphaeales. Pollen morphology is described using both SEM and LM for all 12 species of Hydatellaceae, and using TEM for one species (T. submersa). These observations are compared with pollen data from the other two families of Nymphaeales, Nymphaeaceae and Cabombaceae, including original observations for both genera of Cabombaceae. No significant interspecific variation in pollen morphology occurs in Hydatellaceae, though both of the perennial species (Trithuria inconspicua and T. filamentosa), which could be apomictic, possess at least partially sterile and collapsed pollen. Pollen of Trithuria is small, oblong or rounded (viewed from the distal pole) and monosulcate. The aperture has a distinct margin and extends the full length of the pollen grain. The exine is tectate‐columellate. The tectum is perforate: discontinuous with numerous small perforations randomly scattered over the entire non‐apertural surface. The exine surface is microechinate. In most species of Trithuria, a small percentage of pollen grains possess a trichotomosulcate aperture. In two species, rare atypical grains with striate or partially striate exine sculpturing were found. This striate pattern is very similar to exine sculpturing in Gymnotheca (Saururaceae, Piperales). The presence of anasulcate pollen does not contradict placement of Hydatellaceae within Nymphaeales, but this pollen type is also common among other early‐divergent angiosperms and monocots. Exine sculpturing differs between Cabombaceae, Hydatellaceae and Nymphaeaceae, but this character also differs between the two genera of Cabombaceae and among genera of Nymphaeaceae. Compared with other families of Nymphaeales, Hydatellaceae are relatively uniform in pollen morphology.

Pollen and Seed Morphology of the GenusMarrubium(Lamiaceae) in Turkey

Morphological features of pollen and seeds of 19 Turkish species of the complex genus Marrubium were examined using light and scanning electron microscopy. On the basis of exine sculpturing and seed shape, three main types are recognized in Marrubium. The study revealed that palynological and seed morphological characters are of taxonomic significance in the genus.

Pollen morphology of some Paronychia 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.

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.