Thin-walled Parenchyma Cells Research Articles

Pharmacognostic study of Catharanthus roseus (L.) G. Don, growing in Uzbekistan

In the article, the morpho-anatomical structure of the leaf and stem of Catharanthus roseus species distributed in the local conditions of Uzbekistan was studied, and it was determined that biologically active substances are found in the leaf mesophyll and bark parenchyma of the stem. The following diagnostic characters were determined: in the leaf – dorsiventral type of leaf mesophyll; thick-walled outer walls of the epidermis; amphistomatic leaves; not submerged stomata; chlorophyll-bearing palisade and spongy parenchyma; closed collateral type of conduction bundles; the presence of numerous idioblasts; in the stem there is a more lignified, non-tufted type of structure; libriform extensive; radial rays elongated and short; phloem is extensive, located between the crustal parenchyma and the libriform; the core is not wide, represented by large and small round-oval, thin-walled parenchyma cells containing hydrocyte cells and numerous laticifers. The content of moisture, ash, extractives extracted by heteropolar extractants was also studied, determined by pharmacopoeial methods to establish authenticity and prepare draft regulatory documentation for plant raw materials.

New Information of the Anatomy and Phytochemical Screening of Pentaclethra macroloba (Willd.) Kuntze (Caesalpinioideae-Leguminosae) Seeds

Pentaclethra macroloba (Willd.), whose common name is “pracaxi,” is naturally found in the Amazon region. The present study is aimed at analyzing the anatomy, seed histochemistry, and chemical composition in fatty acid profile of P. macroloba seed oils. Seeds were collected in the cities of Belém, Marituba, and São Domingos do Capim-PA. For the study in light microscopy, scanning electron microscopy, and histochemistry, seeds were sectioned in cross and longitudinal sections of the embryonic axis and fixed in formaldehyde, acetic acid, and 50% ethyl alcohol; neutral-buffered formalin; and formaldehyde and ferrous sulfate and stored in 70% ethyl alcohol. For the anatomical study, the seeds were subjected to the usual techniques of plant anatomy. Histochemical tests were performed on plant material, freehand sectioned, and embedded in histological paraffin with DMSO. The fatty acid profile was determined for gas chromatography (GC-FID). Integument is divided into three strata, monoseriate exotesta, mesotesta formed by several layers of parenchyma cells, and monoseriate endotesta, formed by compressed cells. Cotyledons are composed of thin-walled parenchyma cells with several secretory cavities and secretory idioblasts. The main metabolic classes are lipids, phenolic compounds, carbohydrates, proteins, and alkaloids. The main fatty acids found in P. macroloba oil are oleic, behenic, lignoceric, and linoleic. P. macroloba seeds have important anatomical characteristics for their circumscription in Leguminosae and also in Caesalpinioideae, and their oil is rich in fatty acids essential to the human diet, providing many benefits to the human health, such as fatty acids belonging to the omega family (linoleic, oleic).

Pharmacognostic standardization of Xanthium spinosum L. through scanning electron microscopy and analytical techniques.

The present study was intended to evaluate the pharmacognostic attributes including macroscopy, microscopy, physico-chemical and phytochemical screening of the aerial part of Xanthium spinosum, belonging to family Asteraceae. Morphologically, the leaf was covered with sparsely scattered non-glandular, multicellular hair on adaxial surface, while abaxial surface was reported with dense silvery furs. Leaf showed lamphystomatic nature bearing anomocytic stomata. Various other leaf constant values like vein islets number, vein termination number and palisade cell ratio were also observed and recorded as 4.36 ± 0.5, 3.36 ± 0.5, and 11.82 ± 2.04, respectively. Cross section of the stem showed typical dicot anatomy differentiated into a single epidermal layer followed by few rows of collenchyma cells, thin-walled parenchyma cells followed by closed and collateral vascular bundles having prephloemic sheaths and a central pith. Light and scanning electron microscopy of the powdered drug revealed a variety of tissues and cells fragments having different measurements. Fluorescence analysis of the fine powder treated with different reagents revealed a variety of colors implying as a sign for the presence of various biochemical constituents. Highest and lowest percent extractive value was found in methanol and distilled water which were 29.10% and 9.80%, respectively. Qualitative phytochemical screening revealed the presence of various secondary metabolites like flavonoids, phenols, tannins, glycosides, phytosterols, glycosides, saponins, and coumarins, while quantitative phytochemical screening detected maximum quantity of flavonoids in chloroform followed by methanol and ethyl acetate. The aforementioned studies have been reported first time for the said species, which may be helpful for the standardization of the current taxon.

PRELIMINARY PHARMACOGNOSTICAL, PHYTOCHEMICAL STUDY AND HPTLC ANALYSIS OF COSTUS PICTUS D.DON.

The ancient wisdom in Ayurveda medicine is still not exhaustively explored. Multiple exotic plants existent in India which are not described in classical literature of Ayurveda are commonly referred to as Anukta Dravya (undocumented). Costus pictus D.Don is such a plant, recently introduced in India from Mexico, which is used for renal disorders there. In India, it is used in Diabetes mellitus. This is proven for antidiabetic, antioxidant, anticancerous, antimicrobial and diuretic actions. It is an easily propagated, palatable and cost effective plant. Identification through pharmacognostical and phytochemical studies is essential for the standardization of any plant. The green leaf is narrowly elliptic with 10 to 25cm length and 2.5 to 6cm width. Microscopy revealed presence of vascular bundles, unicellular trichomes in upper epidermis, thin walled parenchyma cells in ground tissue and layers of parenchymatous hypodermis. Powder microscopy showed presence of epidermal parenchyma cells with underlying chlorenchyma group of fibers and fibro vascular bundles.TLC photo documentation revealed presence of many phytoconstituents with different Rf values. Densitometric scan showed many peaks, 10 at 254nm, 11 at 366nm, 6 at 520nm and 9 at 620 nm after derivatisation. Moisture content was 20%. The percentage of total ash, acid insoluble ash, and water insoluble ash was determined. The water soluble extractive value was 22.57 which is highest among all the extracts. The results indicated the presence of alkaloid, steroids, tannins, flavanoids, phenol, carbohydrate and resin in ethanolic extract and steroid, flavanoids, phenols, saponins, tannins and glycosides in water extract.

Vegetative anatomy of Tabernaemontana alternifolia L. (Apocynaceae) endemic to southern Western Ghats, India

The anatomical description of vegetative parts of Taberenaemontana alternifolia L. belonging to the family Apocynaceae was investigated in the present study. The leaves of T. alternifolia is hypostomatic with paracytic stomata, uniseriate epidermis made up of thin-walled parenchymatous cells covered by thin cuticle on both adaxial and abaxial surfaces. The hypodermis comprises of angular collenchyma cells. Mesophyll is dorsiventral containing silica bodies and vascular bundles are bicollateral. The petiole is flattened adaxially and arch-shaped abaxially with a uniseriate epidermis covered by a thin cuticle. The hypodermis is 7-8 layered angular collenchyma cells consisting of laticifers and parenchymatic, cortical layers consisting of silica bodies and thick-walled fibers and U-shaped bicollateral vascular bundles. Secondary growth in stems is characterized by the formation of periderm and thick-walled fibers in the vascular tissues. Bicollateral vascular bundles are covered by sclerenchymatous patches, parenchymatous cortex and pith consist of fibers, laticifers and silica bodies. The root possess unicellular root hairs, compactly arranged thin-walled uniseriate epidermis, 16-18 layered cortex containing silica bodies and fibers, indistinct endodermis, radially arranged vascular bundles and 14-16 arched xylem. Pitted water-storage cells are present in the conjunctive tissue. Lignin deposition was observed in the root stelar region and pith is absent.

Morphological aspects and anatomy of the fruit, seeds and seedlings of Pentaclethra macroloba (willd.) Kuntze (Fabaceae)

Abstract: The aim of this study was to describe the morphology of fruit, seeds and seedlings, as well as the anatomy of the seed and the seedling of Pentaclethra macroloba (Willd.) Kuntze. Morpho-biometry was performed on fifty fruit samples and one hundred seeds. To describe the sequences of the morphological events of the germination stages, ten seeds were placed to germinate. Anatomical analysis was performed in a scanning electron microscope with seed samples and seedling leaves. The species has leguminous type fruit of 16.1 to 45.2 cm length and 4.1 to 7.3 cm width; seeds have a pleurogram and are eurispermic, ovoid, deltoid to elliptical and measure from 3.8 to 6.1 cm length and 2.5 to 5.7 cm width. Anatomically, the cotyledons are composed of thin-walled parenchyma cells with various oil cells. The seedlings have bipinnate leaves, with waxes and simple trichomes at the margins of the adaxial surface and paracytic stomata on the abaxial surface. The epicotyl is slightly twisted, with caducous cataphylls and a first pair of alternate eophylls. Germination is of the phanero-hypogean-reserve type. Taxonomic recognition of this species is possible in the field through the external morphological traits and can help in identification of saplings.

Pharmacognostical Standardization and Phytochemical Studies on the leaves of Solanum torvum Sw

A genus of plant belongs to the family Solanaceae well distributed in India more than 26 species which are found naturalised in India. Solanum torvum Sw. is a medium sized flowering plant in the Solanaceae family that is found in India, Malaysia. Transverse section of lamina showed the adaxial part has thick, short hump; the midrib and the adaxial hump have thin, angular epidermal cells. The upper part of adaxial hump has a few layers sclerenchyma cells. The inner layer of the adaxial midrib also has few layers of thick walled cells. The ground tissue consists of wide circular thin walled parenchyma cells with narrow inter cellular spaces. The vascular system of the midrib showed bi-collateral structure. Non glandular, profusely branched, thick walled, lignified epidermal trichome occurs as both on the veins and lamina. Physico-chemical standards such as Foreign Matter, Total Ash, Water Soluble Ash, Sulphated Ash, Loss on Drying, Water Soluble Extractive, Alcohol Soluble Extractive and Crude Fiber Content in percentage were estimated. Preliminary phytochemical screening of appropriate solvent extracts showed the presence of Alkaloids, Amino Acids, Carbohydrates, Cellulose, Lignin, Fats & Fixed Oils, Flavonoids, Glycosides, Tannins, Proteins, Starch, Steroids and Triterpenoids and absence of Volatile Oil, Mucilage and Pectin. Microscopic analysis and other parameters were informative and provide valuable information in the identification, standardization of Solanum torvum leaves. Keywords: Solanum torvum, Solanaceae, leaf, Microscopical evaluation.

Vegetative anatomy and mycorrhizal morphology of Schoenorchis nivea (Lindl.) Schltr., (Orchidaceae) and their adaptive significance

The anatomical description of the vegetative parts (leaf, leaf sheath, stem and root) and mycorrhizal morphology of Schoenorchis nivea (Lindl.) Schltr., belonging to the subfamily Epidendroideae of Orchidaceae was investigated. Leaves were amphistomatic covered by 10-12 μm thick cuticle, stomata paracytic with small and irregular substomatal chambers. Mesophyll homogenous, composed of thin-walled chlorenchymatous cells. Banded water-storage cells abundant in the mesophyll and the largest vascular bundle occurred at the centre of the leaf. The leaf sheath has both adaxial and abaxial epidermis covered with cuticle, homogenous mesophyll, water-storage cells, raphides and vascular bundles. The stem is surrounded by a uniseriate epidermis, cortex consisting of thick-walled fibers and collateral vascular bundles scattered in the ground tissue. Cortical proliferation was evident in S. nivea stem. Root hairs present in root regions were in contact with the substratum. Root hairs frequently branched at their tips. Root possess 2-3 layered velamen, ∩-thickened exodermal cells, O-thickened uniseriate endodermis, and cortex of thin-walled parenchymatous cells containing raphides and water-storage cells. Cover cells present. Xylem arches are 9-11, with vascular tissues embedded in sclerenchymatous cells. Pith composed of thick-walled sclerenchymatous cells with intercellular space. The stomatal characteristics in leaf, the size of water-storage cells and vascular bundles exhibited significant variation in different plant parts. Intact and degenerating pelotons of orchid mycorrhizal fungi were observed in the root cortical cells. The observations of the present study clearly indicate that S. nivea possesses several anatomical adaptations to thrive in epiphytic habitats.

The mechanism of rain cracking of sweet cherry fruit

Sweet cherry (Prunus avium L.) cracking is a severe limitation in production worldwide. It is thought to be caused by excessive water uptake and a subsequent increase in turgor. When a critical threshold is exceeded (‘critical turgor’) the fruit is believed to crack. Experimental evidence supporting this wide spread concept is lacking. Instead, published data question the critical turgor hypothesis and an alternative explanation must be thought of. This mini review summarizes experimental research published in the last two decades that resulted in an alternative explanation of sweet cherry fruit cracking, the so called Zipper hypothesis. According to this hypothesis, cracking is the result of a series of events that ultimately propagate a crack through skin and flesh and ‘unzip’ the fruit. It is based on the following sequence of events: Tension (stress) develops in the skin during stage III growth and particularly in the cuticle due to a downregulation of genes involved in cutin and wax synthesis. Stress in the skin results in strain and microcracks in the cuticle. Furthermore, surface wetness on and high humidity above the strained cuticle aggravates microcracking. Microcracking impairs the cuticle’s barrier function and focuses water uptake in a particular region of the fruit surface. Water bypasses the cuticle, penetrates into the fruit and moves to sites where water potential is most negative. These are the large thin-walled parenchyma cells of the outer mesocarp that have a more negative osmotic potential than the small thick walled epidermal and hypodermal cells. Water uptake causes individual cells to burst. As a consequence, cell content leaks into the apoplast. Major constituents of sweet cherry such as glucose, fructose and malic acid now occur in the apoplast at comparable concentrations as in the symplast. The consequences are several fold: First, cell turgor decreases and is entirely lost when epidermal cells plasmolyse in the juice from the flesh. Second, malic acid extracts cell wall bound Ca, weakens cell walls and increases the permeability of plasma membranes causing a chain reaction of leakage of adjacent cells. The leakage of cells and the loss of the (low) turgor results in swelling of cell walls, in particular of the pectin middle lamella. Swollen cell walls have decreased stiffness, fracture tension and cell adhesion resulting in the separation of neighbouring cells along their cell walls. The tension generated by the strain of the skin is now sufficient to cause the cells to separate along their swollen walls and to rupture the skin. This process continues at the crack tip where the stress concentrates and causes the crack to elongate. The skin ‘unzips’ in the same way like a ‘zipper’ or a ‘ladder’ that propagates in a piece of knitted fabric.

Vegetative anatomy of the orchid Bulbophyllum sterile (Orchidaceae: Epidendroideae)

The anatomical characteristics of leaf, pseudobulb, and root of Bulbophyllum sterile of the subfamily Epidendroideae (Orchidaceae) were investigated. The anatomical investigation involved observing sections after staining with different stains as well as scanning electron microscopy. Additionally, the cell dimensions were also measured. The amphistomatic leaves of B. sterile had a thick cuticle, paracytic type of stomata, collateral vascular bundles and starch grains. The rhizome had cuticularized uniseriate epidermis and a single layer of the hypodermis. The parenchymatous stem ground tissue was distinguished into outer and inner regions separated by a band of sclerenchymatous tissue. Collateral vascular bundles were distributed in the inner ground tissue. The size of the vascular bundles generally increased from the periphery towards the center. A sclerenchymatous patch covered the phloem pole, whereas the xylem is covered by thin walled parenchymatous cells. The outer surface of the pseudobulb is covered by a thick cuticle. The parenchymatous ground tissue consisted of starch grains, aeration, water and algal cells and scattered collateral vascular bundles. Sclerenchymatous cells covered the phloem pole, whereas the xylem is covered by thin-walled cells. The velamen in B. sterile is single layered consisting of highly elongated compactly arranged cells. Uniseriate exodermis is dimorphic consisting of long and short cells. Cortical cells are differentiated into exodermis and endodermis. The O-thickened endodermal cell layer is interrupted by thin walled passage cells. Pith is sclerenchymatous. From this study, it can be concluded that B. sterile possess anatomical adaptations to xeric conditions in all the vegetative organs.

Vegetative anatomical adaptations of Epidendrum radicans (Epidendroideae, Orchidaceae) to epiphytic conditions of growth

The anatomical properties of leaf, stem, and root of Epidendrum radicans Pav. ex Lindl., belonging to the subfamily Epidendroideae (Orchidaceae) were investigated for adaptations to stressed habitats. The anatomical investigation revealed that leaves of E. radicans have a thick cuticle (3–4 µm) and paracytic type of stomata. Foliar epidermal cells are conical on the adaxial surface and rectangular in the abaxial surface, distinct hypodermis absent, and uniseriate fiber bundles are arranged in both sides of the leaves. The foliar mesophyll is homogenous and starch grains and raphides present. The leaf sheath covering the stem have cuticle restricted to the outer surface and air spaces are present. The stem has a cuticulerized uniseriate epidermis and a uniseriate hypodermis. The cortex and a parenchymatous ground tissue of the stem are separated by a layer of sclerenchymatous band. Vascular bundles are collateral and their size generally increases from the periphery towards the center. A sclerenchymatous patch covers the phloem pole, whereas the xylem is covered by thin-walled parenchymatous cells. The roots possess Epidendrum-type velamen. Cover cells present. Uniseriate dimorphic exodermis consists of U-thickened long cells and thin-walled passage cells. The endodermal cells O-thickened, pericycle sclerenchymatous, xylem 10–14 arched. The pith is sclerenchymatous, but parenchymatous at the center. The anatomical examination of E. radicans revealed adaptations to moisture stress conditions like thick cuticle covering the leaves and stem, water storage cells, multilayered velamen and dimorphic exodermis.

Involvement of peroxidases in structural changes of barley stem

The aim of this work was to investigate anatomical characteristics of barley (Hordeum vulgare) internodes and to reveal the connection with activity of guaiacol-peroxidases, their isoenzyme profiles, lignin and cellulose content. Three lower internodes were sampled at elongation stage. Internodes differed in their anatomical features by showing that lignin deposition follows developmental pattern. Epidermis and hypodermis in the first internode were characterized by continuous layer of the lignified cells while in the second and third internode thin walled parenchyma cells could be observed in the hypodermis. These observations were in accordance with increment of peroxidase activity from the first to the third internode. Two acidic and two basic isoforms of peroxidases were present. The third internode had higher total soluble protein content and lower dry weight as well as Klason lignin content in comparison to the first and second internode. Studying lignification process in barley stem by using anatomical and physiological approach will provide valuable information regarding developmental changes connected with lignin deposition in the stem.

Morphology and Overall Chemical Characterization of Willow (Salix sp.) Inner Bark and Wood: Toward Controlled Deconstruction of Willow Biomass

The morphology and chemical composition of the inner bark of four willow hybrids were analyzed as a step toward complete willow biomass valorization. The inner bark consisted of highly delignified bundles of thick-walled sclerenchyma fibers and nondelignified surrounding tissue of thin-walled parenchyma cells. In comparison with willow wood fibers, the sclerenchyma fibers were longer, they had a very narrow lumen and their walls were made of up to eight separate layers. One fourth of the dry mass of the inner bark was formed of ash and acetone extractable substances. Although the lignin-to-polysaccharide ratio was similar in the inner bark and wood, their polysaccharide compositions were different. While glucose and xylose were the main monomers in wood, the inner bark had also high arabinose and galactose contents. In addition, more rhamnose was present in the inner bark which was indicative of its higher pectin content.

Exploring biomass deconstruction by phase-contrast tomography

Alternative and renewable fuels derived from lignocellulosic biomass offer a potential alternative to conventional energy sources. Biorefinery feedstocks are usually pretreated with acid, alkali, or high temperature/pressure treatments before enzyme hydrolysis to yield glucose and other useful sugars for fermentation to ethanol. If plant cell walls are to be efficiently deconstructed by conversion technologies, then a detailed understanding of their structural organization in different length scales is required. Here, a novel imaging technique provided an opportunity to probe the deconstruction of the biomass structure by alkali pretreatments under mild operation condition. High-resolution phase-contrast tomography (PCT) provided unique aspects on the recalcitrance-related changes of physical structures spanning macro and micrometer length scales. This approach revealed that the thickness of the plant cell walls was considerable reduced on the whole particle. However, long cracks could be particularly observed crossing over the thin-walled parenchyma cells, making each the fibrovascular bundles totally or partially unattached and independent. Such particle fragmentation was responsible for increasing its external specific surface area about 10 times, while the total surface area of the inner porous structure only doubled in value. The PCT and imaging processing techniques can be applied to different processing routes for ethanol conversion, providing new insights into the underlying mechanisms of biomass deconstruction.

Pharmacognostical Standardization and High Performance Thin Layer Chromatography (HPTLC) of Root of Saccharum officinarum Linn. (Poaceae)

The purpose of the present study is to investigate the pharmacognostical characteristics of the roots of Saccharum officinarum Linn. (poaceae) to establish standardized parameters. Macroscopic, microscopic, and physicochemical evaluation; preliminary phytochemical analyses and high performance thin layer chromatography (HPTLC) profile were done for qualitative phytochemical evaluation. Roots are grey to blackish brown, fibrous, solid, jointed, odour and taste not distinct. Transverse section of both thin and fairly thick root showed presence of epidermal, hypodermal layers, aerenchymatous cortex and a wide stele. Powder microscopy revealed presence of long thick walled fibers with pointed ends, vessels and tracheids with reticulate, scalariform and bordered pitted walls and thin walled parenchyma cells. Physicochemical parameters viz. percentage of moisture content (9.3% w/w), total ash (7.5% w/w), acid insoluble ash (5.0% w/w), water soluble extractive (6.9% w/w) and ethanol soluble extractive (3.8% w/w) were also determined. Various groups of phytoconstituents found in the plant are carbohydrate, steroids, flavonoids, saponins, tannins and phenolic compound. HPTLC profile of hydroalcoholic extract showed presence of twelve different components in the solvent system, chloroform: methanol (9:1, v/v). The different salient diagnostic features established in this study will help for proper identification and standardization of the drug in crude form, and then the plant material can be used for further studies.

Comparative study on secondary xylem and formation of successive cambia in stems and roots of Antigonon leptopus Hook. & Arn. (Polygonaceae)

Antigonon leptopus Hook. & Arn. (Polygonaceae) being a climbing member increases their stem and root diameter by forming successive cambia. The first successive ring of cambium initiates as small segments from the parenchymatous cells located on the inner side of group of primary phloem fibres. These small arcs of cambia produced secondary xylem internally and phloem externally while portion between newly initiated cambial arcs exclusively produce thin walled parenchyma cells on either side. With the increase in age, vessel diameter and their frequency not only decreased in roots but also showed complete absence of wider vessels or observed occasionally in thick roots. In thick stems, strands of lignified derivatives once closely arranged became separated and appeared as embedded in parenchymatous ground mass. At this stage, these parenchyma cells underwent proliferation and formed small arcs of meristematic cells and produce vascular elements. Formation of xylem and phloem from these arcs appear like vascular bundles embedded in conjunctive tissue. Since, major portion of the stem is composed of parenchyma cells, presence of fibre with distinct bordered pits instead of wider vessels might be related with additional mechanical support and to provide additional path for the water conduction in absence of wider vessels in roots.

Macro-microscopic standards of an abortifacient druglangali (tubers of Gloriosa superba Linn.)

Gloriosa superba Linn., a striking herbaceous tendril climber with underground cylindrical white tuberous root, forms as a source of Langali -a upavisha dravya. The root contains an alkaloid colchicine (0.23- 0.3%). Though a poisonous root, having the magnificent therapeutic benefit, deliberate attempt to record its standard macro-microscopic features by photomicrography is lacking. Matured, authenticated tuberous roots were collected from its natural habitat. Macro-microscopic and powder characters were recorded using standard methodology. Thin walled parenchymatous cells with plenty of simple and compound starch grains, collateral vascular bundles scattered in the ground tissue, and absence of any sclerenchymatous tissue are microscopic recordings of transverse section of root. The powder has shown the presence of starch grains and cells of scaly leaves in surface view. This study along with photographic atlas will serve as reference for the correct identification of the drug and to differentiate it from their substitute and adulterants.

Development of Successive Cambia and Structure of Secondary Xylem of Ipomoea Obscura (Convolvulaceae)

Abstract Stems of Ipomoea obscura Ker Gawl., increase in thickness by forming multiple rings of cambia. Stems 5-6 mm thick produce parenchymatous derivatives which divide repeatedly to form small arcs of cambium. Several such small arcs initiate simultaneously and form a ring of small cambial arcs. After the formation of a few xylem and phloem elements, all these arcs are interconnected by transdifferentiation of parenchyma cells present between the cambial arcs and constitute a complete cambial cylinder. This newly formed cambium is functionally bidirectional: earlier- formed arcs produce xylem centripetally and phloem centrifugally, while later-formed segments exclusively produce thin-walled parenchyma cells on either side. Young stems are circular in cross section but as stem thickness increases they become oval to elliptic or lobed and dumbbell-shaped. Xylem rays are mostly uni- or biseriate and thin-walled, but multiseriate rays characteristic for a climbing habit are observed occasionally. In thick stems, the marginal ray parenchyma in most of the samples becomes meristematic and develops ray cambia which exclusively produce sieve elements. Similarly, parenchyma cells produced from later-formed cambial segments give rise to several irregularly oriented vascular bundles. The secondary xylem is diffuse porous, with indistinct growth rings and is composed of fibriform and wider vessels, fibres, and axial and ray parenchyma cells, while phloem consists of sieve elements, companion cells, and axial and ray parenchyma cells.

Dryocosmus kuriphilus-induced Chestnut Galls and Their Inhabitants

Studies were conducted to characterize altered tissues of larvae-infested buds and stem and leaf galls induced by Dryocosmus kuriphilus Yasumatsu on Chinese chestnut trees (Castanea mollissima Blume) and to describe gall inhabitants. Bud and gall samples were collected from chestnut trees growing in Mantua, OH, on 2 Mar. and 3 May 2012, respectively, and prepared for microscopy. Uni- and multilocular larval chambers containing one D. kuriphilus larva per chamber were observed in buds and stem galls. Evidence of insect-modified Castanea cells was present as a two-layer zone of hypertrophied plant cells adjacent to the larval chambers before budbreak on 2 Mar. By 3 May, stem and leaf galls were in the growth and differentiation stage of development. Within galls, torn cell walls and disorganized organelles were visible in the protoplasm of cells surrounding ovoid-shaped larval chambers. A continuous layer of nutritive cells with large nuclei and nucleoli, abundant lipid bodies and mitochondria, and fragmented vacuoles was contiguous to larval chambers. At the outermost region of the nutritive tissue, cells had recently divided. Larger vacuolated cells, with slightly thickened walls, were observed surrounding recently divided cells. Thin-walled parenchyma cells in the chestnut gall cortex had large vacuoles with fewer organelles than those of the nutritive layer. Vascular tissue within the gall was connected with that of the plant host tissue outside the gall. In some chestnut galls, a single parasitoid larva was found attached to a D. kuriphilus larva. Each parasitoid larva had six pairs of setae on its head capsule, a pair of clypeal setae, a notched labrum, a semicircular lobed labium, 13 post-cephalic body segments, and rows of long, erect setae on all body segments.

THE SECRETORY TISSUE OF ALOES AND THEIR ALLIES

ABSTRACT The presence of thin-walled parenchymatous cells in the inner bundle sheath of species of the liliaceous genera Aloe, Chamaealoe, Astroloba, Lomatophyllum, Gasteria, Haworthia, Asphodeline, Asphodelus, Bulbine, Eremurus and Trachyandra was observed and described. Some species, however, have lignified sclerenchymatous cells in this position and this is general in Kniphofia. Cells in this region produce a secretion in the form of a copious exudate in many species of Aloe, or much sparser contents in the case of related genera. The leaves of most species contain small amounts of anthraquinones, while the related anthrone-C-glycosides accumulate in others. A wide range of other phenolic substances occurs, recognized as distinct zones on thin layer chromatograms, but mainly consisting of unidentified compounds. It is not certain if synthesis occurs in the thin-walled bundle sheath cells or if these have only a storage function. Another layer of rather smaller parenchymatous cells in the outer bundle s...