Tricolporate Aperture Research Articles

Systematic study in Cressa cretica L. (Convolvulaceae) species from Lake Qarun, El-Fayoum province, Egypt

Cressa cretica L. is a monotypic species belongs to the plant family Convolvulaceae, tribe Cresseae. It is an erect, small, dwarf shrub, commonly grown in coastal areas and considered as an important medicinal plant with many therapeutic effects. Individuals of this species became restricted in specific areas in Egypt in became under threat of extinction. This study dealt with careful examination of the external and leaf internal structure beside pollen grain morphology. The study aims to understand the species morphological characteristics and protect it from localization and destruction processes. The results showed that the leaf macro- and micro-morphological characters are of the halophytic ones, with long unicellular hairs as well as T-shaped hairs and sunken stomata. The leaf internal structure has mesophyll differentiated into one layer palisade and spongy layers full of ca-oxalate crystals and salt glands distributed in the mesophyll. Pollen grains productivity was few and they are small, spheroidal to subprolate with tricolporate aperture and tectate perforate with supra-tectum granules. The results obtained show that Cressa cretica has external and internal halophytic structure in addition to few small pollen grains. Germination experiments needed to test the pollen productivity of this plant under non-saline habitats for its conservation.

Pollen Morphological Study of Some Selected Flowering Plants within Adekunle Ajasin University Main Campus, Akungba-Akoko, Ondo State, Nigeria

On the Adekunle Ajasin University Main campus, Akungba-Akoko, Ondo State, Nigeria, the pollen morphological study of seven (7) flowering plant species representing three (3) angiospermic plant Families (Asteraceae, Euphorbiaceae, and Fabaceae sub-family Caesalpinoideae) was examined, analyzed, and studied palynologically to determine the morphological features and attributes as an aid in the identification and classification of its members within each family. Pollen grains from fresh polleniferous materials were extracted using acetolysis methods. Detailed morphological evaluations were performed at x100 magnification. Results showed similarities and differences between species in the same genera, as well as differences between species in other families. Pollen study of these species revealed several similarities between species within the same family. Aperture type, forms, pollen grain size, sculpturing pattern, pollen dimension, and exine pattern were all studied for differences and similarities. Euphorbia hirta L and Euphorbia heterophylla L, both Euphorbiaceae species, have tricolpate apertures, are prolate in shape, reticulate, and contain small to medium pollen sizes. Asteraceae has tricolporate apertures, prolate spheroidal shapes, spinate, short and long spines, and pollen sizes ranging from microscopic to enormous (Ageratum conyzoides L, Tithonia diversifolia, and Tridax procumbens). Pollen from the family Fabaceae subfamily Caesalpinioideae (which includes Caesalpinia pulcherrima (L.) Swartz. and Senna alata (Linn.) Roxb) were found to be subprolate, coarsely reticulate, tricolporate, and with pollen sizes ranging from medium to large. Aperture measures such as number and diameter, pollen size, and spine height were suggestive in all of the species studied. Because all of the species studied exhibited comparable form and symmetry, they were grouped together and assigned to the same family.

Eurypollinic pollen of the Anacardiaceae differentiates taxa

The pollen morphology of 11 Anacardiaceae species from the Mexican State of Veracruz was studied. Pollen grains were acetolyzed and examined under light and scanning electron microscopy to determine whether their morphological characteristics are useful to differentiate taxa in this family. Photomicrographs were obtained with both types of microscopes and used as the basis for describing the pollen. Pollen descriptions included traits such as shape, the type and number of apertures, exine ornamentation, size of the polar and equatorial axes, and diameter in polar view. Most species have isopolar pollen grains, with tricolpate or tricolporate apertures. Only Pistacia mexicana has pentaporate pollen. Pollen grains exhibit a triradial or radial symmetry in polar view; their shape in equatorial view can be prolate-spheroidal, subprolate, or prolate. The size of axes in equatorial view, diameter in polar view, and the exine ornamentation show distinctive characteristics in each species. However, the most common ornamentation types are microreticulate and microstriate. Ten pollen types were identified based on combinations of traits such as the type and number of apertures, shape in equatorial and polar view, and exine ornamentation. The results confirm that the eurypollinic pollen of Anacardiaceae is valuable for differentiating taxa, highlights the importance of studying pollen morphology and contributes to increasing the knowledge about the pollen morphology of this family in Mexico.

Pollen Morphology of Some Taxa of Rosaceae from Garhwal Himalaya - I

Palynological investigation of a particular taxonomic group helps in classification, identification and delimitation of its taxa. The present study deals with pollen morphology of 19 species of Rosaceae of Garhwal Himalaya, Uttarakhand, India. The measurements and observations of grains were made through light microscopy and scanning electron microscopy. Pollen grains of studied species were isopolar, monad and radially symmetric with tricolporate aperture. Pollen shapes varied from prolate or sub-prolate to spheroidal. In the majority of species, amb was elliptical in equatorial view with obtuse to acute end at poles and triangular in polar view. The highest and lowest polar axis lengths were recorded for Pyrus communis (46 ± 1.6 μ m) and Potentilla indica (20.1 ± 0.7 μ m) respectively. The average polar/equatorial diameter ratio (P/E ratio) was 1.4 μm which ranged between 1.1 μ m (Fragaria nubicola) to 1.7 μ m (Chaenomeles japonica). The studied taxa were grouped into four pollen types (categories) on the basis of exine ornamentation, viz. straite, straito-perforate, straito-reticulate and straito-verrucate. The study revealed that the morphological characteristics of pollen provide significant information to categorize various taxa.

Morphological, Anatomical, and Palynological Studies of Lasianthera africana P. Beauv (Stemonuraceae) from some Parts of Southern Nigeria

This study examined Lasianthera africana P. Beauv based on, anatomical and palynological parameters. The anatomical studies were carried out with freehand sectioning. The species is hypostomatic, the epidermal cells are are irregular, with undulating anticlinal walls. The stomata types are anomocytic, and anisocytic. The midrib has bicollateral vascular bundles and the petiolar vascular bundle is arced with rib traces on both sides of the wings. Calcium oxalate and tannin occurred in the lamina, midrib, petiole and stem. The pollen grains are smooth, intectate, with thick exine, with tricolporate aperture, and with an equatorial diameter of 21.5-25.8 µm. These features are diagnostic and confirm the placement of this species in Stemonuraceae.

Comparative pollen morphology of the Kirengeshoma (Hydrangeaceae)

The genus Kirengeshoma, in the family Hydrangeaceae, is considered by some botanists to be monotypic while others divide it into two species, K. palmata, native to Japan and China, and K. koreana, native to South Korea. We have conducted a comparative pollen morphological study of five populations of the two putative species to investigate this question. Pollen morphological characteristics were observed with scanning and transmission electron microscopy. The pollen characteristics of all five populations were similar. All populations dispersed pollen as the monad and the pollen grain shape were either spheroidal or sub-spheroidal and approximately 12 to 18 µm in diameter, falling in the small grain category. In all five populations, the pollen grains were iso-polar and radio-symmetrical, with tri-colporate apertures. Additionally, pollen surface sculpture patterns of all populations were semi-tectate and reticulate. As a result, the two putative species differed in that the pollen grains of K. palmata were smaller, and their endexine slightly thicker, than those of K. koreana. Despite these differences, we conclude that the similar pollen morphology of all the populations does not support separating them into two independent species. However, different species of angiosperms often have similar pollen morphology. Therefore, we suggest that the genus should be considered to consist of these two independent species unless further morphological or molecular evidence to the contrary is forthcoming.

Pollen morphology of selected Indian species from subfamily Polygonoidae (Polygonaceae)

Pollen morphology of 28 species and 5 varieties representing 8 genera of subfamily Polygonoidae (Polygonaceae), collected from various altitudinal ranges of Darjeeling Himalaya, sub-Himalayan Terai, Duars, Gangetic plains, Sundarbans and Western plateau of West Bengal and NE India, were examined critically under light (LM) and scanning electron microscope (SEM) to explore their distinctive features. Anthers were processed through acetolysis method and obtained grains were properly studied, measured and photographed. The shape, size, aperture type and exine ornamentation of pollen grains served as a reliable features in current study as taxonomic tool for the authentic identification at species and varietal level. The studied characters under LM and SEM were further statistically analyzed through ANOVA, PCA, Pearson Correlation Matrix to understand the interrelationship among the taxa and pollen grains were recorded monad, isopolar and radiosymmetric type. Pantoporate, tricolpate, tricolporate aperture type and exine ornamentation appears to be valuable and unique characters were found useful tool for the delimitation and differentiation of closely related taxa.

Pollen morphology of the least known families of the order Asterales

The recent discovery of pollen grains assigned to the earliest branch of Asteraceae from Cretaceous sediments in Antarctica prompted us to examine the pollen from five lesser known members of Asterales (Alseuosmiaceae, Argophyllaceae, Pentaphragmataceae, Phellinaceae and Roussaceae) that might also be represented in fossil sediments. Detailed pollen morphology in the basal members of the order Asterales has, until now, been incomplete. Our study reveals a highly variable pollen morphology of these small, and poorly explored families. The tricolporate character of Phelline macrophylla and the zono-hexaporate aperture of Roussea simplex are described for the first time. Pollen of Alseuosmiaceae share granulate structure and tectum little sculpturate, with the exception of Periomphale which is verrucate; Crispiloba has an isolated position due to very large size and porate aperture. Pollen of Argophyllaceae is relatively homogeneous sharing tricolporate aperture, tectum little sculpturate and columellate structure. Pentaphragmataceae is distinguished by its smallest pollen, with oblate-peroblate shape, di or tricolporate aperture and psilate exine. Roussaceae is the most diverse family at level of dispersion unit, aperture type, sculpture and structure of exine. The morphological characters here analysed can be potentially used to unmask fossil dispersed pollen grains with unknown botanical affinity.

English

Strychnos spinosa Lam. belongs to the family Loganiaceae.  It is a small tree.  The morphological and anatomical features of the leaves, stem, flower and fruit were studied. S. spinosa has a cylindrical stem with a pair of spines at irregular spaces. The leaves are opposite, decussate, petiolate with palmate venation. The petals are greenish in colour, tubular with five lobes. There are numerous white hair-like appendages at the neck of the corolla tube. The androecium is epipetalous and attached close to the bottom of the corolla tube. The flower is a cyme, occurring in threes, with the middle one being the oldest. The fruit is a berry with very hard pericarp. It turns from light green when unripe to bright yellow when ripe. The anatomy of the leaf revealed presence of rosette crystals and intraxylary phloem which is more pronounced in the mid rib and petiole. “Kranz” structure was observed in the transverse section of the leaf. Anisocytic stomata are numerous in the abaxial (lower) epidemis but absent in the adaxial epidemis. The anatomy of the stem showed the presence of crystals in the cortex. Both solitary and multiple vessels are found in the transverse section.  In the tangential longitudinal section, most of the rays were four to seven cells wide, but a few were uniseriate, biseriate and triseriate. Most of the pollen grains were triangular in the polar view but a few were quadrangular. Those that were triangular exhibited tricolporate aperture while those that were quadrangular had tetracolporate aperture. The sculpturing was perforate and were not very compact.   Key words: Strychnos spinosa, rosette crystals, intraxylary phloem, pollen dimorphism, heterogenous, rays.

Anatomical, micromorphological and palynological studies on Turkish endemic Heracleum platytaenium Boiss. (Apiaceae)

Heracleum platytaenium is monocarpic and strongly aromatic plant and differs from other species with stout stem, obovate-suborbicular mericarp. Fruits are dorsally compressed. In this study, the anatomical features of the mericarp, as well as micromorphological characteristics of the pollen, fruit and leaf of pollen H. platytaenium have been investigated. A distribution map of this species is also given. Flattened mericarps are with filiforme dorsal ribs, and wings. Four vittae are found in the both, dorsal and commissural sides. The fruit surfaces are reticulate and striate structure. The leaves surface are reticulate and rugose structure. Mericarp surfaces are hairy. The hair shape of fruit and leaf are ribbon-type. The pollen grains are prolate in shape and tricolporate aperture. The exine sculpturing of this species is rugulate. The plants are used as a folk medicinal herb and food

Insights on Ardisia and Stylogyne (Myrsinoideae–Primulaceae) based on pollen morphology

Species of Ardisia (A. catharinensis, A. guianensis, and A. semicrenata) and Stylogyne (S. amazonica, S. latifolia, S. orinocensis, S. poeppigii, S. schomburgkiana, S. surinamensis, S. laevigata, and S. leptantha), with doubtful circumscriptions because of shared overlapping or continuous characters, were investigated to clarify their taxonomy. The study of these species allowed us to evaluate previous studies in which pollen morphology was applied to distinguish the genus Stylogyne from Ardisia. Acetolyzed pollen grains were measured, described, and illustrated using light microscopy, while nonacetolyzed pollen grains were analyzed using scanning electron microscopy. Both Ardisia and Stylogyne have pollen grains on isopolar monads that may be subprolate, prolate, oblate spheroidal, or prolate spheroidal, with a reticulate and heterobrochate exine, and tricolporate apertures. Differences among species usually consist of the size of the grains, length of the colpi (or size of the apocolpi), and size of the polar area and reticulum. Granules inside the lumina, which were not observed in pollen grains of Ardisia in previous studies, are reported here. Pollen morphology proved to be uninformative to differentiate the genera Ardisia and Stylogyne, but useful to distinguish some related species within each genus.

A palynological study of the genus Smyrnium (Umbelliferae) from Turkey

In this study, the pollen morphology and exine structure of six taxa of the genus SmyrniumL. (Umbelliferae) were investigated using light microscopy and scanning electron microscopy (SEM). Eight micromorphological characters (pollen shape, apocolpium, mesocolpium, polar length, equatorial width, exine thickness, colpus length and colpus width) of pollen grains of Smyrnium have been identified. The palynological observations revealed that pollen grains of all studied taxa of Smyrnium were prolate in shape and posses tricolporate aperture. Tectal surface sculpture was not a good criterion to identify particular taxa from Smyrnium. The pollen of which is characterized by rugulate, the pollen ornamentation was similar in all studied taxa. In addition the taxa could be included in sub-rectangular pollen type as classified by Cerceau – Larrival. Key words: Smyrnium, Umbelliferae, pollen, scanning electron microscopy.

New insights into the pollen morphology of the genus Mutisia (Asteraceae, Mutisieae)

The pollen morphology from 67 collections representing 52 species of Mutisia was analyzed by means of light, scanning electron and transmission electron microscopy. Pollen of Mutisia is comparable to that of the more widespread type found in Mutisiinae. The pollen grains of the genus are characterized by the spheroidal-subprolate to prolate shape, large size, tricolporate aperture, with mesoaperture, exine Mutisia type, with sculpturing microechinate to rugulate or microechinate-rugulate. This basic pollen type is very variable in size, endoaperture shape, and exine thickness of the pollen grains. A new type of arrangement of columellae was observed in pollen of Mutisia section Mutisia (e.g., M. stuebelli, M. microphylla, and M. sodiroi). It is suggested that it might have harmomegathic significance. The pollen morphology and polymorphism are discussed with regard to functional mechanisms and possible evolutionary significance.

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 and viability of some Indian mangroves

A study on pollen morphology of four common Indian mangroves from Sundarbans mangrove swamps, three species from the family Rhizophoraceae (Bruguiera sexangula Laur., Ceriops tagal Perr.and Rhizophora mucronata Lamk.) and one species from the family Avicenniaceae (Avicennia marina Forsk.) was carried out. Shape of the pollen grains were prolate, prolate spheroidal and subprolate with tricolporate apertures. Surface ornamentation of the studied taxa was reticulate, finely reticulate or scabrate. Pollen grain viability of the said taxa was determined by stain test (1% aceto-orcein) under in situ condition and percentage of viable pollen production was recorded. The result revealed that all the studied taxa produce a fairly good amount of viable pollen grains in natural condition, an indication that they are good propagule producer in the long run. Pollen grain germination and measurements of pollen tube length using different sucrose concentrations (0.2, 0.6, 1.0, 1.2, 1.6 and 2.0%). Maximum pollen fertility and pollen tube length occurred in 2% sucrose solution in case of A. marina and B. sexangula, whereas 1.6% in C. tagal and 1.0% in R. mucronata. A strong positive correlation exist between pollen germination and pollen tube length, but there was a hardly relation between sucrose concentration and pollen tube length.

Microsporogenesis in Monocotyledons

This paper critically reviews the distribution of microsporogenesis types in relation to recent concepts in monocot systematics. Two basic types of microsporogenesis are generally recognized: successive and simultaneous, although intermediates occur. These are characterized by differences in tetrad morphology, generally tetragonal or tetrahedral, although other forms occur, particularly associated with successive division. Successive microsporogenesis is predominant in monocotyledons, although the simultaneous type characterizes the ‘lower’ Asparagales. Simultaneous microsporogenesis also occurs inJaponolirion and Petrosavia (unplaced taxa), some Araceae, Aponogeton, Thalassia andTofieldia (Alismatales), Dioscorea, Stenomeris and Tacca (Dioscoreales), and some Commelinanae: Arecaceae (Arecales), and Cyperaceae, Juncaceae and Thurniaceae (Poales). Simultaneous microsporogenesis is of phylogenetic significance within some of these groups, for example, Asparagales, Dioscoreales and Poales. An intermediate type is recorded in Stemonaceae (Pandanales), Commelinaceae (Commelinales) and in Eriocaulaceae and Flagellariaceae (Poales). There is little direct relationship between microsporogenesis type and pollen aperture type in monocots (except for trichotomosulcate and pantoporate apertures), although trichotomosulcate apertures in monocot pollen, and equatorial tricolpate and tricolporate apertures in eudicot pollen, are all related to simultaneous microsporogenesis.

Pollen morphology of Lagotis (Scrophulariaceae)

The pollen grains of 18 species of Lagotis have been examined using light microscopy and scanning electron microscopy of whole and fractured pollen. The grains are characterized by tricolporate apertures with smooth to sparsely granular ectocolpus membranes; lolongate endoapertures with unthickened margins included within the ectocolpi; relatively large exinous processes over the endoaperture; and columellate, semitectate, reticulate to microreticulate exines with or without supramurial processes. Lumina are reduced in size toward the colpus, but the transition is gradual, and a sharply bounded, differentially sculptured colpus border is absent. Lagotis pollen is distinct from that of the Selagineae and Globularia and indistinct from that of some Veroniceae; however, the characters shared with the latter are of wide occurrence in the Scrophulariaceae. Pollen morphology supports the distinction between L. brachystachya and L. stolonifera. It is consistent with the postulated close relationship between L. micrantha and L. integra, and provides no evidence to support the reestablishment of L. cashmeriana, L. minor, L. pallasii, or L. kunawurensis as species distinct from L. glauca. Key words: pollen morphology, Lagotis, Globularia, Selagineae, Veroniceae.

THE NATURE OF THREADLIKE STRUCTURES AND OTHER MORPHOLOGICAL CHARACTERS IN JACQUESHUBERIA POLLEN (LEGUMINOSAE: CAESALPINIOIDEAE)

Threadlike structures were observed on many pollen grains of Jacqueshuberia amplifoliola, J. purpurea, and J. quinquangulata of the Leguminosae/Caesalpinioideae. Each end was attached to the highly reticulate polar exine surface of different grains. The consistency of this observation, hence, the absence of free thread ends, is interpreted to mean that they should be considered as either exine bridges or exinial connections rather than viscin threads, although, most likely functionally homologous to viscin threads. Other significant morphological characters were the tricolporate apertures and strikingly lamellate foot layer and endexine.

The Nature of Threadlike Structures and Other Morphological Characters in Jacqueshuberia Pollen (Leguminosae: Caesalpinioideae)

Threadlike structures were observed on many pollen grains of Jacqueshuberia amplifoliola, J. purpurea, and J. quinquangulata of the Leguminosae/Caesalpinioideae. Each end was attached to the highly reticulate polar exine surface of different grains. The consistency of this observation, hence, the absence of free thread ends, is interpreted to mean that they should be considered as either exine bridges or exinial connections rather than viscin threads, although, most likely functionally homologous to viscin threads. Other significant morphological characters were the tricolporate apertures and strikingly lamellate foot layer and endexine.

Fine Structure of Mistletoe Pollen. IV. Eurasian and Australian viscum L. (Viscaceae)

Fifteen Eurasian and Australian species of Viscum L. were examined by light, scanning, and transmission electron microscopy. Pollen characters divide the species into two groups, each correlated with differences in habit and inflorescence structure: Group I (12 spp.) characterized by psilate or slightly sculptured exines and a non-uniform ektexine pattern and Group II (3 spp.) possessing highly sculptured (echinate, rodlet) surfaces and uniform ektexine patterns. Within each of the groups, pollen characters divide the species into several subgroups. Among Group I, species V. nepalense, V. heyneanum and V. ovalifolium are particularly close. The Group I species, V. trilobatum, is placed in its own subgroup primarily because of its uniform ektexine pattern—a unique feature among Asian and Australian Viscum. Of the three Group II species, V. album and V. alniformosanae are palynologically almost indistinguishable. Pollen of the Group II V. cruciatum, though exomorphologically similar to V. album, is closest ultrastructurally to the Indian V. trilobatum. Overall, the most common and probably basic pollen characters among the Eurasian and Australian species include: subprolate, rounded convex almost spherical shapes; tricolporate apertures, and non-uniform sculpturing and ektexine patterns. Oblate-spheroidal or prolate-spheroidal shapes, prominent sculpturing, and a uniform ektexine pattern are derived characters largely restricted to the Eurasian and Asian Group II species (V. album, V. alniformosanae, V. cruciatum).