Outer Periclinal Cell Walls Research Articles

Seed morphology in the genus Matthiola R. Br. (Brassicaceae): Identification of species and systematic implications

AbstractSeed coat morphology of 34 species of Matthiola R.Br. has been studied using light and scanning electron microscopy to assess their investigative value for systematic studies. Macro‐ and micromorphological characters, including seed shape, color, size, wing, and radicle position relative to cotyledons, epidermal cell shape, anticlinal boundaries, and periclinal cell wall are presented. Seed shape, color, and radicle position relative to cotyledons have limited taxonomic significance, as their variation is unhelpful. There against, seed size, wing, and seed coat ornamentation present informative characteristics that can be used professionally in distinguishing the studied taxa. Six different types of seed anticlinal cell wall boundaries are recognized and five different outer periclinal cell wall shapes are described. The sculpture of the secondary cell wall varies from striate, micropapillate to microreticulate, and smooth to fine folds. The taxonomic and phylogenetic implications of seed coat micromorphology were compared with those of the existing gross morphological and molecular data. Seed character analysis offered useful data for evaluating the taxonomy of Matthiola both on subgeneric and sectional levels. Seed micromorphological characters provide evidence that M. odoratissima and M. ovatifolia should be preserved as separate species. In addition, M. ghorana is not conspecific with M. graminea. Furthermore, M. tricuspidata was unique in the seed characters. A key to the identification of the examined taxa based on seed characters is provided.

Micromorphology of endemic Centaurea glaberrima subsp. divergens (Asteraceae)

In this study, the micromorphology of the vegetative and reproductive structures of the endemic Centaurea glaberrima Tausch subsp. divergens (Vis.) Hayek (Asteraceae), using scanning electron microscope (SEM), is presented for the first time. Uniseriate whip-like non-glandular and biseriate glandular trichomes are found on the surface of all aboveground parts (stem, leaves, peduncles, involucral bract). On the adaxial leaf epidermis ribbed thickenings (striation pattern) of outer periclinal cell walls, slightly curved anticlinal cell walls and anomocytic stomata are noticed. Rugose abaxial surface with thorny protuberances of the involucral bract is documented. Corolla is glabrous with longitudinally parallel epidermal cells with distinct straight outline. Isopolar, radially symmetric and tricolporate microechinate pollen grains are seen. Short stylar hairs, without cuticular striations, are present along the outer sides of the style, while the inner sides (abaxial surface) constitute the papillate stigmatic surface. Microcharacters found in cypsela are as follows: slightly ribbed body; rotund base; lateral and concave insertion; short, unicellular curly acute trichomes; smooth epidermis; fine-sulcate ornamentation; rod shaped epidermal cells with short, obtuse end walls and straight anticlinal walls; poorly developed minutely dentate pericarp rim; and dimorphic pappus with bristles of different length and morphology, with pinnules restricted to the margins of the bristles. The results obtained contribute to knowledge about the micromorphology of the studied endemic species and provide features for its better identification. The taxonomic significance of the analyzed characters is discussed. Some well defined microcharacters of the studied species might have taxonomic value.

How does micromorphology reflect taxonomy within the Xeranthemum group (Cardueae-Asteraceae)?

Comparative micromorphological analyses were conducted on five members of the Xeranthemum group, both perennial (Amphoricarpos exsul and Shangwua masarica) and annual (Chardinia orientalis, Siebera pungens and Xeranthemum inapertum), using scanning electron microscopy (SEM) and SEM coupled with an energy-dispersive spectrometer (SEM-EDS) in order to evaluate whether micromorphological characters correlate with current phylogenies. “Puzzle-like” epidermal cells at the adaxial leaf surface with smooth outer periclinal walls and slightly sinuate anticlinal walls, and lack of weddellite crystals on the involucral bracts are shared by A. exsul and Sh. masarica and Sh. denticulata, while sinuate anticlinal adaxial leaf epidermal cell walls, weddellite crystals on the involucral bracts and an aristate-paleaceous pappus link together Ch. orientalis, S. pungens and X. inapertum. The following traits are probably species-specific: a glabrous adaxial leaf epidermis and cypsela surface, and a plumose-setose pappus in Sh. masarica; a barbate-aristate pappus in A. exsul; irregular shape of cells of the adaxial leaf epidermis with cuticular corrugations, and a papillose cypsela surface in Ch. orientalis; channeled anticlinal borders of adaxial leaf epidermal cells, and wax deposition on the surface of involucral bracts in X. inapertum; and strongly ribbed thickenings of outer periclinal adaxial leaf epidermal cell walls and involucral bracts with a whitish patch of appressed trichomes on their central surface in S. pungens. All of the examined species exhibit vermiform trichomes on the stems and on the abaxial leaf surfaces, adaxial detachment area of cypselae, an asymmetrical carpopodium and direct insertion of the pappus to the pericarp. Our results revealed valuable qualitative characters that facilitate species identification and contribute to a better understanding of relationships between genera. Optimization of these traits onto phylogenetic analyses suggests that some characters found on leaves and involucral bracts are likely due to adaptations of perennial ancestors to xeric habitats.

Differential growth of pavement cells of Arabidopsis thaliana leaf epidermis as revealed by microbead labeling.

In numerous vascular plants, pavement cells of the leaf epidermis are shaped like a jigsaw-puzzle piece. Knowledge about the subcellular pattern of growth that accompanies morphogenesis of such a complex shape is crucial for studies of the role of the cytoskeleton, cell wall and phytohormones in plant cell development. Because the detailed growth pattern of the anticlinal and periclinal cell walls remains unknown, our aim was to measure pavement cell growth at a subcellular resolution. Using fluorescent microbeads applied to the surface of the adaxial leaf epidermis of Arabidopsis thaliana as landmarks for growth computation, we directly assessed the growth rates for the outer periclinal and anticlinal cell walls at a subcellular scale. We observed complementary tendencies in the growth pattern of the outer periclinal and anticlinal cell walls. Central portions of periclinal walls were characterized by relatively slow growth, while growth of the other wall portions was heterogeneous. Local growth of the periclinal walls accompanying lobe development after initiation was relatively fast and anisotropic, with maximal extension usually in the direction along the lobe axis. This growth pattern of the periclinal walls was complemented by the extension of the anticlinal walls, which was faster on the lobe sides than at the tips. Growth of the anticlinal and outer periclinal walls of leaf pavement cells is heterogeneous. The growth of the lobes resembles cell elongation via diffuse growth rather than tip growth.

Ультраструктура семян видов рода Iris L. s.l. (Iridaceae) из Украинских Карпат

We have studied the ultrastructure of five species of genus Iris L., which grow in the Ukrainian Carpathians – I. aphylla L., I.graminea L., I. pseudacorus L., I. sibirica L. and I. sintenisii Janka. We have found that in shape seeds are rounded-fusiform (I. aphylla), D-shaped (I. pseudacorus, I. sibirica, I.graminea), pyriform (I. sintenisii). The hilum is rounded or drop-shaped, small, by position – basal (I. graminea), with well-seen roll (I. graminea, I. aphylla). The seeds of I. sibirica and I. pseudacorus have wing, that surround all the seed (wing is smaller in seeds of I. pseudacorus). The wings are absent in seeds of other species. Тhe curvature of anticlinal cell walls (straight) is common for all studied species. The seeds of all examined species characterized by polygonal cells of testa, they are isodiametric (I. aphylla, I. sintenisii, I. graminea), or prolonged (I. sibirica, I. pseudacorus) – mostly on the wing. The boundaries of cells of testa are practically not visible, anticlinal cell walls are tightly merged only in I. sintenisii seeds, in other species seeds they are seen. The anticlinal cell walls in I. aphylla and I. graminea are raised in relation to surface of periclinal cell walls. The outer periclinal cell walls are concave (I. sintenisii, I. aphylla), flat (I. graminea), or convex (I. pseudacorus, I. sibirica). The sculpture of outer periclinal cell walls is smooth (I. graminea, I. sintenisii, I. aphylla), or furrowed (I. sibirica, I. pseudacorus). Considering all the above features, we concluded that seeds of studied species are characterized by coliculate (I. sibirica, I. pseudacorus), reticulate (I. aphylla), indistinct-coliculate with slightly convex periclinal cell walls (I. graminea) or indistinct-cellular (I. sintenisii) relief.

A role for fruit structure in seed survival and germination of Swartzia langsdorffii Raddi beyond dispersal.

Diaspore structure has been hypothesised to play a role in seed viability and/or germination of recalcitrant seeds, especially for Swartzia langsdorffii. Thus, this work aims to (i) investigate the insitu contribution of pericarp and aril on seed viability and germination, and (ii) identify morphoanatomical traits of S.langsdorffii diaspores that allow its desiccation-sensitive seeds to remain viable. The role of the pericarp and aril in seed survival and germination was investigated by placing the whole fruit, whole seeds (arillate seed) and bare seeds (without aril) in soil in the forest understorey, assessing germination, emergence, dead, firm and predated seeds, and water content of pericarps, arils and seeds. Correlation analysis was performed between environmental variables and physiological parameters. Histochemical features of diaspores were also investigated. Pericarp water content fell after several months, while the aril maintained its water content. Seeds did not lose water even without the presence of the pericarp and aril. However, presence of the pericarp promoted seed water content, viability and germination long after dispersal. The embryo had a thickened outer periclinal cell wall. Pericarp and aril are not essential to prevent water loss in seeds, but do help to retain seed moisture, favouring viability maintenance and promoting germination during the rainy season. Morphoanatomical features of seeds are suggested as main factors that reduce water loss. Survival of these desiccation-sensitive seeds upon dispersal during the dry season appears to be facilitated by multiple diaspore features that prevent viability loss.

Oil-resin glands in Velloziaceae flowers: structure, ontogenesis and secretion

Many Velloziaceae flowers present conspicuous glands, whose taxonomic value has already been highlighted. However, until now, their micromorphology, anatomy and ultrastructure have not been investigated, nor have the natures and possible functions of their exudates. Our aim was to investigate distribution, ontogenesis, structure, and secretion mechanisms of glands of Barbacenia flava and Vellozia intermedia and to discuss their possible ecological functions. Samples were prepared according to standard methods for investigations of plant anatomy, scanning electron microscopy, and transmission electron microscopy. Histochemical tests were performed, and focal field observations were made in the study site. The capitate stalked glands on the pedicel, tepals and hypanthium are covered by a sticky secretion that is released in the gland head through the outer periclinal cell walls and cuticle. Secretions are produced in the epidermal and subepidermal cells that contain structural components typical of mixed, mainly lipophilic secretions. Bacteria were found inside the oil-resin gland cells of both species. The Meliponina bees Trigona spinipes and Tetragonisca angustula were observed collecting resin from both species, but were not involved in pollination. Our observations clearly indicate that flower glands of B. flava and V. intermedia are oil-resin secreting and remain active in secretion from very young buds, through to immature fruit. New, smaller glands replace senescent glands by divisions near the base of the original stalk cells. Oil-resin glands have a number of different, but important functions, including the interaction with Meliponina bees, protection against water loss and high temperatures by ultraviolet screening, and anti-desiccant properties.

Nutlet morphology and its taxonomic implication in some taxa of Lamiaceae in Egypt

Nutlet morphology of 28 taxa belonging to 15 genera of Lamiaceae were examined using light and scanning electron microscopy. The taxa included representatives of the three subfamilies Ajugoideae, Lamioideae and Nepetoideae which all collected especially from Sinai, Egypt. Morphological characters, including nutlet shape, color, size; hilum (shape, length x width and position); epidermal cell shape; anticlinal walls (level, undulation, thickness and secondary sculpture); outer periclinal cell walls (level and secondary sculpture) are presented. The reticulate type was the most common among the studied taxa. Four types of basic anticlinal cell wall boundaries were recognized and many different shapes of the outer periclinal cell wall were described. Nutlet ornamentation, shape, size, colour and particularly hilum characters proved to be good taxonomic characters for the Egyptian Lamiaceae taxa. A key for the identification of the investigated taxa based on nutlet characters is provided.

Leaf anatomical studies of Chamaecrista subsect. Baseophyllum (Leguminosae, Caesalpinioideae): new evidence for the up-ranking of the varieties to the species level

This study aims to determine whether morphoanatomical characters of the leaves of the species of Chamaecrista sect. Absus subsection Baseophyllum could be used to support an up-ranking of C. cytisoides varieties to the species level as previously defined by molecular studies. The significance of anatomical adaptive strategies to arid environments is also discussed. Standard light microscopy techniques and histochemical tests were used for both morphoanatomical and histochemical characterization of the leaves. All the species studied share a single-layered epidermis, actinodromous–camptodromous–brochidodromous type of venation, vascular bundles surrounded by layers of fibers bounded externally by a sheath of cells containing solitary crystals, enlarged tracheids at the vein endings, vascular petiole/rachis tissue with a parenchymatous pith, accessory vascular bundles, mucilage idioblasts and hypodermis in the mesophyll, colleters, and non-secretory trichomes. The position and type of stomata, type of mesophyll, number of palisade and spongy parenchyma layers, position of mucilage idioblasts in the mesophyll, and the number of accessory vascular bundles of petiole/rachis provided useful characters for discriminating the eight species of the subsect. Baseophyllum. Histochemical tests reveal the presence of total polysaccharides, pectins, mucilage and phenolic compounds in the idioblasts. Other xeromorphic characters such as thickened outer periclinal cell walls, compact mesophyll, mucilage idioblasts and hypodermis in the mesophyll may help enable the studied species to survive in exposed sunny areas.

Spatiotemporal Secretion of PEROXIDASE36 Is Required for Seed Coat Mucilage Extrusion in Arabidopsis

The epidermal cells of the Arabidopsis thaliana seed coat, which correspond to the second layer of the outer integument (oi2), contain large quantities of a pectic polysaccharide called mucilage within the apoplastic space beneath the outer periclinal cell wall. Immediately after seed imbibition, the mucilage is extruded and completely envelops the seed in a gel-like capsule. We found that a class III peroxidase family protein, PEROXIDASE36 (PER36), functions as a mucilage extrusion factor. Expression of PER36 occurred only in oi2 cells for a few days around the torpedo stage. A PER36-green fluorescent protein fusion was secreted into the outer cell wall in a polarized manner. per36 mutants were defective in mucilage extrusion after seed imbibition due to the failure of outer cell wall rupture, although the mutants exhibited normal monosaccharide composition of the mucilage. This abnormal phenotype of per36 was rescued by pectin solubilization, which promoted cell wall loosening. These results suggest that PER36 regulates the degradation of the outer cell wall. Taken together, this work indicates that polarized secretion of PER36 in a developmental stage-dependent manner plays a role in cell wall modification of oi2 cells.

Endosperm and aleurone cell structure in barley and wheat as studied by optical and Raman microscopy

Grain ultrastructure is of utmost importance when designing grain processing procedures in the food industry. In this study, wheat and barley grain components were localised using optical and Raman microscopy. The optical microscopic analyses were performed using several selective stains to localise β-glucan, protein and starch or autofluorescence to image the ferulic acid and other fluorescing substances. Alternatively, Raman microscopy was applied to localise the grain components without any need for preceding staining or other sample pretreatment. Both methods provided consistent information on the grain structures, illustrating the distribution of polysaccharides, aromatics and protein in endosperm and aleurone layers. In aleurone layers of both barley and wheat, a distinct difference between the anticlinal and periclinal cell walls was observed. The anticlinal cell walls were enriched with aromatic substances which were present in remarkably lower concentrations in the inner periclinal cell walls but for barley, an even higher concentration in the outer periclinal cell wall was observed. In addition, Raman spectroscopy illustrated the detailed distribution of substances across the aleurone cell walls: β-glucan was adjacent to proteins and it was deficient in the middle lamella whereas arabinoxylan was enriched in the outer cell wall layers and middle lamella.

Leaf anatomy, ultrastructure and plasticity of Coffea arabica L. in response to light and nitrogen availability

Phenotypic plasticity in response to environmental variation occurs at all organizational levels and across temporal scales within plants. However, the magnitude and functional significance of this plasticity is little explored in perennial species. We examined the influence of different light regimes and nitrogen (N) availability on the morphological and physiological plasticity of coffee seedlings (Coffea arabica L.). Potted plants were grown under 100% and 50% of full sunlight and were fertilized with Hoagland’s solutions containing 0, 16 or 23mM N. Most leaf traits responded to light with a classic 100% vs. 50% dichotomy [e.g., compared with those grown under 100% of full sunlight, 50% leaves had a thinner palisade mesophyll and a lower leaf mass per area (LMA) for improved light capture]. The outer periclinal cell walls in both epidermises exhibited thick epicuticular wax and three distinct layers. Chloroplasts of the mesophyll cells were densely occupied by thylakoids and starch grains. These characteristics were observed most clearly in plants supplemented by nitrogen or in those grown in shade conditions. Large starch granules were observed, but no membrane injuries were observed in either treatment. The plasticity index was high for the physiological traits that are associated with photoprotection and the maintenance of a positive carbon balance under 50% of full sunlight but was low for most morpho-anatomical features.

Microculture effects on leaf epidermis and root structure in Sclerocarya birrea subsp. caffra

Micropropagation of woody plants is beset by a number of challenges such as cell and tissue abnormality, which ultimately affect survival of plantlets ex vitro. The aim of the study was to evaluate the effects of in vitro microenvironments, in particular photoperiod, on the structure of the leaf epidermis and adventitious roots under photomixotrophic conditions. Control plants were grown under photoautotrophic conditions in a growth chamber. Stomatal density (number of stomata per mm 2) on the abaxial leaf surfaces was highest for the control (221.9 ± 13.99) and the 16-h photoperiod treatment (206.6 ± 15.28). Stomata of plants grown under a 16-h photoperiod had fully expanded kidney-shaped guard cells that closely resembled stomata in the control plants. Formation of epicuticular wax was least for in vitro plants grown under a 24-h photoperiod. One of the main structural differences was the relative thickness of the inner and outer periclinal cell walls of the root epidermis between the control plants and in vitro plantlets. Control plants developed a thicker epidermis compared to that of in vitro plantlets. The root endodermis in the control plants was also comparatively thicker and more regular than that of in vitro plantlets. Control plants had a greater proportion of vascular tissue relative to the total area of the root cross-section compared to in vitro plants due to the development of xylem and phloem tissues. A micropropagation system that facilitates the modification of the in vitro microclimate may reduce the structural abnormalities of conventional microcultures.

Seed Morphology of Some Species of <i>Indigofera</i> (Fabaceae) from Saudi Arabia (Identification of Species and Systematic Significance)

Seeds of 18 species of Indigofera L. were examined with the scanning electron microscope and the light microscope. Macro- and micromorphological characters, including seed shape, colour, size, surface, epidermal cell shape, anticlinal boundaries, outer periclinal cell wall and relief of outer cell walls, are presented. Two types of basic anticlinal cell wall boundaries and two types of relief outer cell walls are recognized and two different shapes of the outer periclinal cell wall are described. A key for the identification of the investigated taxa based on seed characters is provided.

Micromorphology of the Seed Envelope ofEphedraL. (Gnetales) and Its Relevance for the Timing of Evolutionary Events

Micromorphology of the seed envelope of Ephedra (Gnetales) is known to be variable, but variation patterns have never been systematically documented. We test the usefulness of this feature for species determination and subclade delimitation in Ephedra and investigate the relationship of this character to infrageneric evolutionary patterns. Most species have a basically smooth seed envelope, which in some species appears slightly striate or reticulate due to convex or depressed outer periclinal cell walls. Ephedra rhytidosperma from China and Ephedra torreyana from North America have transverse lamellae formed by the epidermis. A papillate surface is found in respective close relatives of these two species. Micromorphology of the seed envelope is generally not useful for species identification or subclade delineation. The amount of variation is low, and intraspecific variation, which in some cases seems to be correlated with hybridization and/or introgression, complicates species recognition. Furthermore, parallel evolution of similar micromorphological patterns in unrelated subclades of Ephedra is evident and cannot be explained by similar seed dispersal mechanisms. The Asian species with transverse lamellae or papillae on the seed are dispersed by frugivores whereas similar American species are anemochoric. Transverse ridges occur in several Early Cretaceous fossil seeds with affinity to Ephedra. However, our results indicate that the resemblance between these fossils and extant taxa with similar features is superficial and convergent. In line with other recent studies, we find that Cretaceous ephedroids are extinct stem relatives to the extant clade.

Seed morphology of some species of TephrosiaPers. (Fabaceae) from Saudi Arabia Identification of species and systematic significance

AbstractSeed morphology of eight species belonging to the genus Tephrosia Pers. were examined by using light and scanning electron microscopy. Macro‐ and micromorphological characters, including seed shape, colour, size, surface, epidermal cell shape, anticlinal boundaries, outer periclinal cell wall and relief of outer cell walls, are presented. Two types of basic anticlinal cell wall boundaries and two types of relief outer cell walls are recognized and two different shapes of the outer periclinal cell wall are described. A key for the identification of the investigated taxa based on seed characters is provided (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Seed coat morphology and its systematic significance in Juncus L. (Juncaceae) in Egypt

Abstract The seed morphology of nine taxa of Juncus from Egypt has been investigated using light and scanning electron microscopy, to determine the importance of seed coat features as taxonomic characters. Macro- and micromorphological characters, including seed shape, color, size, seed appendages, epidermal cell shape, anticlinal boundaries, and outer periclinal cell wall and secondary cell wall sculpture are presented. Four types of seed appendages are recognized: (i) seeds with two appendages; (ii) seeds without appendages; (iii) seeds with minutely a piculate at one end; and (iv) seeds with minutely a piculate at both ends. Two types of anticlinal cell wall boundaries, (i) raised-channeled, straight and (ii) raised, straight or sinuous, and three different shapes of outer periclinal cell wall are described: (i) flat; (ii) concave; and (iii) flat to slightly concave. The secondary sculpture of the cell wall varies from striate to microreticulate or reticulate, and smooth to finely folded. Seed characters provide useful data for formulating the taxonomy of Juncus both on the subgeneric and sectional level. A key for the identification of the investigated taxa based on seed characters is provided.

In situ variation in leaf anatomy and morphology of Andira legalis (Leguminosae) in two neighbouring but contrasting light environments in a Brazilian sandy coastal plain

Andira legalis (Vell.) Toledo is a legume shrub widespread along the sandy plains of the Brazilian coast. It occurs both shaded, in forest habitats, or exposed to full sunlight, in the vegetation islands growing on sand deposits. Previous studies reported a high range of morpho-physiological variation for this species along a geographical gradient. This study compared leaf morphology and anatomy of A. legalis in two distinct but adjacent light environments: a dense forest (shaded) and a scrub of Palmae (exposed). We studied the amplitude of variation for these traits within a small (0.5 ha) geographical area. Leaf anatomy parameters were measured for five leaves collected from five plants in each habitat. The parameters measured were leaf and mesophyll thickness, thickness of the outer periclinal cell wall, thickness of the adaxial and abaxial epidermis and vascular bundle transversal section area, and also common epidermal cells, stomata and trichome density. Leaf morphology parameters were obtained from five leaves of each of 20 plants in each site. Dry and fresh weights were measured to obtain leaf specific mass and succulence. All anatomy and morphology parameters, except trichome density, were significantly higher for the sun-exposed plants. Less expected, however, was the marked qualitative difference between exposed and shaded plants: in the former the mesophyll had a unilateral symmetry (i.e., the whole mesophyll occupied by photosynthetic tissue), whereas in the latter there was a dorsiventral symmetry (i.e., partly palisade and partly spongy parenchyma). Such amplitude of variation shows that even within a small geographic area A. legalis has a broad ecological plasticity.

Surface replicas of normal and vitrified leaves of Datura insignis, Barb Rodr

Vitrification is a morphological and physiological disorder affecting plants during their in vitro vegetative propagation. Vitrified plants have a poor survival rate when transferred from in vitro to greenhouse conditions, a fact mainly due to water loss and dissecation. It has been shown that normal and vitreous leaves of Datura insignis differ in the frequency of normal and abnormal stomata. The purpose of this work was to compare the surface of normal and vitreous leaves of D. insignis, using a modification of the platinum/carbon replica method. Adaxial and abaxial leaf surfaces of normal plantlets have a smooth and homogenous cuticle. A granular aspect, probably due to leaf age, rarely occurs at the periphery of the epidermal cells. Both adaxial and abaxial leaf surfaces of vitrified plantlets show discontinuities in the cuticle, occurring at several regions of the outer periclinal cell walls. However, such discontinuities are most noticeable in the region between adjacent epidermal cells. Fibrils 20-30 nm thick show a random arrangement or an oriented pattern in cuticular discontinuities. In D. insignis vitrified plantlets, adaxial and abaxial leaf cuticle has discontinuities or gaps which may cause an increase in cuticular transpiration contributing to the low survival rate of vitrified plantlets.

Seed morphology of some species of Convolvulaceae from Egypt (Identification of species and systematic significance)

AbstractSeed morphology of 31 taxa belong to six genera of Convolvulaceae from Egypt were examined by using light and scanning electron microscopy. Macro‐ and micromorphological characters, including seed shape, colour, size, surface, epidermal cell shape, anticlinal boundaries, outer periclinal cell wall and relief of outer cell walls, are presented. Three types of basic anticlinal cell wall boundaries and three types of relief outer cell walls are recognized and four different shapes of the outer periclinal cell wall are described. A key for the identification of the investigated taxa based on seed characters is provided. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)