Water-storage Cells Research Articles

Comparative study on root anatomy of six species of Himalayan Dendrobium Swartz

Comprehensive knowledge of plant anatomy is an absolute necessity for accurately identifying taxa during their vegetative phase. Orchidaceae family has been extensively studied in the Himalayan region, with a focus on morphology and floristics. However, the anatomy of orchid roots has not been investigated in detail. This study examines the root anatomy of six Himalayan Dendrobium species (D. chrysanthum, D. densiflorum, D. longicornu, D. nobile, D. rotundatum, and D. transparens) using standard plant anatomy techniques. Qualitative and quantitative traits were observed and analysed, including the multi-layered velamen, stele and cortical tissue area, and number of xylem strands, which are distinct characteristics of genus Dendrobium. ANOVA and Tukey's test at 5% significance level were used to quantitatively examine cross-sections of the roots and identify significant differences. All six studied taxa possess velamen tissues with cells having spirally thickened walls, and a single-layered exodermis with cells of varying sizes. The cortex was multi-layered and contained parenchymatous water-storage cells, while a uniseriate endodermis with passage cells were observed. D. chrysanthum and D. rotundatum had xylem and phloem elements embedded in parenchymatous tissues, whereas D. densiflorum, D. longicornu, D. nobile, and D. transparens had xylem and phloem elements embedded in sclerenchymatous tissues. Cell sizes in different root tissues varied significantly. A dichotomous key based on the root anatomical traits for the identification of these Dendrobium species is provided. Future research is suggested to explore additional parameters and to conduct experiments to understand its anatomical response to epiphytism.

Mechanisms of hydraulic conductivity in the leaf galls of Meunieriella sp. (Cecidomyiidae) in Avicennia schaueriana (Acanthaceae): does vascularization explain the preferred sites of induction?

Intralaminar galls of Meunieriella result from ground tissue proliferation in leaves of Avicennia schaueriana, a typical halophytic mangrove. We tested if the preferred sites of gall induction were the midribs and secondary veins (SV) at the basal leaf portion, where the galls were expected to be largest; and if the vascular system in galls and adjacent regions was altered to favour water supply in galls, thus increasing their growth. Gall induction sites and gall sizes were quantified according to leaf portions and regions. Anatomical and histometric analyses in vascular and ground tissues of galls and adjacent regions were compared to equivalent regions of non-galled leaves. The galls were largest at basal sites on leaves, the midrib and SV. More galls occurred on the apical portion of the leaf, and on the leaf blade and secondary vein regions. Changes in shape and vascular system area, number and diameter of vessel elements were detected in both galls and adjacent regions. Fewer and smaller-sized vessel elements were observed in regions proximal to the galls and inside them. Gall size is not related with preferred induction sites, which could be explained by factors such as thermal balance. Alterations in the vascular system indicate reduced hydraulic conductivity in the xylem in the proximal region and inside galls, leading to water leakage to gall parenchyma cells. This compensatory mechanism explains the expansion and proliferation of water storage and spongy parenchyma cells in the galls, explaining the higher growth in more vascularized regions.

Genetic variation and molecular characterization of Zygophyllum coccineum L. ecotypes of the iron mining area of El-Wahat El-Bahariya in Egypt

Remediation and mitigation processes can recover the ecosystems affected by mining operations. Zygophyllum coccineum L. is a native indigenous xerophyte that grows in Egypt's Western Desert, particularly around the iron mining ore deposits, and accumulates high rates of potentially toxic elements (PTEs) in its succulent leaves. The present study evaluated the genetic variation and molecular responses of Z. coccineum to heavy metal stressful conditions in three sites. Results revealed that Z. coccineum bioaccumulation capacity was greater than unity and varied amongst the three locations. In response to heavy metal toxicity, Z. coccineum plants boosted their antioxidative enzymes activity and glutathione levels as a tolerance strategy. Anatomically, a compact epidermis, a thick spongy mesophyll with water storage cells, and a thicker vascular system were observed. Protein electrophoretic analysis yielded 20 fragments with a polymorphism rate of 85%. The antioxidant genes (CAT: catalase, POD: peroxidase and GST: polyphenol oxidase) showed greater levels of expression. In addition, DNA-based molecular genetic diversity analyses using Start Codon Targeted (SCoT) and Inter Simple Sequence Repeat (ISSR) markers yielded 54 amplified fragments (i.e. 24 monomorphic and 30 polymorphic), with 12 unique fragments and a polymorphism rate of 55.5%. The greatest PIC values were recorded for SCoT-6 (0.36) and for both of the 14 A and 44 B ISSR primers (0.25). Diversity index (DI) of all SCoT and ISSR amplified primers was 0.23. The present findings reveal the distinct heavy metal's adaption attributes of Z. coccineum, indicating its improved survival in severely arid mining environments.

Comparative vegetative anatomy of three Elaeocarpus species from the Western Ghats, Southern India.

The vegetative anatomy of Elaeocarpus angustifolius Blume, Elaeocarpus tuberculatus Roxb., and Elaeocarpus variabilis Zmarzty were investigated to illustrate anatomical variations. Plant materials were free-hand sectioned using a razor blade and stained with different staining solutions. The maceration technique was used to assess stomatal characteristics. Elaeocarpus leaves have abaxial epidermis with paracytic stomata and curved anticlinal walls in E. angustifolius, straight walls in other two species. Trichomes were absent in E. angustifolius.havMesophyll dorsiventral, midvein cortex contains starch grains, and vascular tissues enclosed by thick-walled sclerenchymatous cells. The petioles of all the three species possess unicellular epidermal hairs, collenchymatous hypodermis, and cortex containing druses and crystals, and vascular tissue enclosed by sclerenchymatous fibers. Water-storage cells are absent in petioles of E. angustifolius. Anatomical features of Elaeocarpus stem include epidermal hairs, epidermis covered by thin cuticle, the collenchymatous hypodermis and vascular integrity with entire cylinder enclosed by sclerenchymatous fibers. Pith contains water-storage cells. Starch grains absent in the pith cells of E. tuberculatus. The roots of Elaeocarpus possess unicellular root hairs, cortex 12-14 layered in E. tuberculatus and E. variabilis and 10-12 layerd E. angustifolius, Endodermis O-thickened and pericycle single-layered in all the examined Elaeocarpus species. Vascular bundles are arranged radially. Lignin deposition occurred in stellar region of roots. Water-storage cells present in the stelar regions of E. variabilis. The study revealed significant anatomical differences between the three Elaeocarpus species and most of these anatomical features may be used as markers for the identification of these species. RESEARCH HIGHLIGHTS: Comparative anatomy of three south Indian Elaeocarpus was studied. Leaf mesophyll layers varied in all the Elaeocarpus species. Crystals was present in petiole of all examined Elaeocarpus species. Starch grains was absent in stems of E. tubercuatus, but present in E. variabilis. Water-storage cells observed in stellar region of E. variabilis.

Leaf Water Storage and Robustness to Intermittent Drought: A Spatially Explicit Capacitive Model for Leaf Hydraulics.

Leaf hydraulic networks play an important role not only in fluid transport but also in maintaining whole-plant water status through transient environmental changes in soil-based water supply or air humidity. Both water potential and hydraulic resistance vary spatially throughout the leaf transport network, consisting of xylem, stomata and water-storage cells, and portions of the leaf areas far from the leaf base can be disproportionately disadvantaged under water stress. Besides the suppression of transpiration and reduction of water loss caused by stomatal closure, the leaf capacitance of water storage, which can also vary locally, is thought to be crucial for the maintenance of leaf water status. In order to study the fluid dynamics in these networks, we develop a spatially explicit, capacitive model which is able to capture the local spatiotemporal changes of water potential and flow rate in monocotyledonous and dicotyledonous leaves. In electrical-circuit analogs described by Ohm's law, we implement linear capacitors imitating water storage, and we present both analytical calculations of a uniform one-dimensional model and numerical simulation methods for general spatially explicit network models, and their relation to conventional lumped-element models. Calculation and simulation results are shown for the uniform model, which mimics key properties of a monocotyledonous grass leaf. We illustrate water status of a well-watered leaf, and the lowering of water potential and transpiration rate caused by excised water source or reduced air humidity. We show that the time scales of these changes under water stress are hugely affected by leaf capacitance and resistances to capacitors, in addition to stomatal resistance. Through this modeling of a grass leaf, we confirm the presence of uneven water distribution over leaf area, and also discuss the importance of considering the spatial variation of leaf hydraulic traits in plant biology.

Anatomical adaptations and mycorrhizal morphology of two threatened Eulophia (Orchidaceae) growing in southern Western Ghats, India

The vegetative anatomy of Eulophia spectabilis (Dennst.) Suresh and Eulophia pulchra (Thouars) Lindl., of subfamily Epidendroideae (Orchidaceae), of subtribe Eulophiinae was investigated to bring out the anatomical differences, mycorrhizal morphology and also their adaptation to thrive in stressful xerophytic habitats. Transverse sections of plant parts were freehand sectioned and stained with various staining solutions for anatomical investigation. Stomatal characteristics were examined by maceration technique. The leaves of both Eulophia species shared similar anatomical characteristics including tertracytic stomata on abaxial surface, uniseriate epidermis on both the surfaces, homogenous mesophyll comprising of intercellular spaces and collateral vascular bundles. Fibre bundles are present only in the leaves of E. pulchra. Likewise, the anatomy of leaf-sheath in both the species resembles those of the leaves except for the large air chambers. The pseudobulb of E. pulchra consists of parenchymatous ground tissue containing air chambers, raphides, starch grains, and water-storage cells and collateral vascular bundles. Starch grains are present only in the rhizomes of E. pulchra ground tissues. In roots, the velamen is undifferentiated in E. pulchra, but distinguished into epivelamen and endovelamen in E. spectabilis. Starch grains are present in root pith cells in E. pulchra. The cell dimensions of most plant parts varied significantly (P<0.05) among the Eulophia species. Contrarily there were no significant (P>0.05) differences in orchid mycorrhizal colonization between the Eulophia species. Thus, these ground orchids possessed several anatomical features that enable them to thrive in dry habitats.

Anatomical study of Orchidaceae epiphytes species occurring in indigenous territory in the Parque Estadual da Serra do Tabuleiro (P.E.S.T.), Santa Catarina, Brazil

Abstract Besides their ecological importance, epiphytic species of Orchidaceae play economic and social roles through their commercialization and some are at great risk of extinction. The objectives of this study were to characterize the leaf and root anatomy of fourteen epiphytic Orchidaceae species, which occur in indigenous territory in the Parque Estadual da Serra do Tabuleiro (P.E.S.T.), Santa Catarina, Brazil and to identify adaptive anatomical characteristics related to the epiphytic habit. The species are commercialized by the Guarani and were collected during interviews and guided tours with Guarani in the indigenous territory. The results reveal the species have many morphoanatomical structures that are useful during water shortages resulting from the epiphytic habit. Notable characteristics are related to reserving water (i.e., pseudobulbs and a hypodermis with water-storage cells) and resistance to desiccation in the leaf (i.e., conspicuous cuticle, suprastomatic chamber and extraxylary and pericyclic fibers) and root (i.e., tilosomes and/or exodermal thickening and cortex cells with phi thickenings or sclereids). Descriptions and the identification of adaptive characteristics of epiphytic plant species are useful for conservation and cultivation studies, especially for plants commercially used by the Guarani Indians.

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.

The Developmental Enhancement of a C4 System With Non-Typical C4 Physiological Characteristics in Salsola ferganica (Kranz Anatomy), an Annual Desert Halophyte.

Variations of photosynthetic structures in different tissues or cells are in coordination with changes in various aspects, e.g. physiology, biochemistry, gene expression, etc. Most C4 plant species undergo developmental enhancement of the photosynthetic system, which may present different modes of changes between anatomy and physiology/biochemistry. In the current study, we investigated a Kranz-type C4 species Salsola ferganica with the progressive development of photosynthetic (PS) structure, performance of PS physiology, induction of PS enzymes, and transcriptional and translational regulation of PS genes, results revealed that S. ferganica presented C3 type anatomy in cotyledons but C4 type in leaves (C3/L4), with the C4 system separation of initial carbon fixation in the palisade mesophyll (M) cells and the following incorporation into triosephosphates and sugars in the bundle sheath (BS) cells, respectively. The BS cells continuously surrounded the vascular bundles and water storage cells in leaf anatomic structure. Compared to the single-cell C4 species Suaeda aralocaspica, S. ferganica exhibited similar developmental enhancement of C4 syndrome temporally and spatially in anatomic structures, enzyme activities, and gene expression, which suggests that completion of differentiation of the photosynthetic system is necessary for a C4 assimilation pathway. Besides, S. ferganica also displayed some different characteristics compared to S. aralocaspica in photosynthetic physiology, e.g. a more flexible δ13C value, much lower phosphoenolpyruvate carboxylase (PEPC) activity, and an insensitive response to stimuli, etc., which were not typical C4 characteristics. We speculate that this may suggest a different status of these two species in the evolutionary process of the photosynthesis pathway. Our findings will contribute to further understanding of the diversity of photosynthesis systems in Kranz-type C4 species and the Salsola genus.

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.

Physiological responses of orchid pseudobulbs to drought stress are related to their age and plant life form

As storage organs for water and nutrients, pseudobulbs play an important role in the survival of orchids. However, the differences in morphological and physiological responses of pseudobulbs to drought stress between epiphytic and terrestrial orchids remain undefined, and little is known about the physiological imparity of different-aged pseudobulbs. We investigated the anatomy and changes in physiology of pseudobulbs in an epiphytic orchid (Cymbidium tracyanum) and a terrestrial orchid (C. sinense) and compared their responses and recovery during and after periods of drought stress. In particular, “ramets severance treatment” and “multiple leafless pseudobulbs treatment” were applied for C. tracyanum to verify the utilization strategy for the stored water. When compared with C. sinense, the pseudobulbs of C. tracyanum have larger water-storage cells and higher water content, and the enhanced water storage of C. tracyanum can be used and recovered more rapidly. And they had more flexibility in shifting stored nonstructural carbohydrates. The remarkably high concentration and different change trends of abscisic acid (ABA) between different-aged pseudobulbs under drought stress were only found in C. tracyanum. When pseudobulb age was considered, the stored water and carbohydrate changed more rapidly in the youngest pseudobulbs of both species in response to stress. Our results indicated that the pseudobulbs differ in their means for coping with drought conditions according to their life form and age. These findings contribute to our understanding about the functional diversification of pseudobulbs and their strategies for ecological adaptations.

Comparative vegetative anatomy and mycorrhizal morphology of three South Indian Luisia species (Orchidaceae) with the note on their epiphytic adaptations

The anatomical characteristics of the vegetative structures and mycorrhizal morphology of Luisia pulniana Vatsala, Luisia tenuifolia Blume and Luisia tristis Hook.f. belonging to the subfamily Epidendroideae (Orchidaceae) were investigated. Luisia species have amphistomatic leaves covered by a thick cuticle, paracytic stomata, and homogenous mesophyll containing raphides, silica bodies, water-storage cells and collateral vascular bundles. The leaf sheath has an upper epidermis of conical papillate shaped cells, homogenous mesophyll, water storage cells, raphides and sclerenchymatous fibers. The process of stem thickening through cortical proliferation was observed for the first time in Luisia species. The uniseriate epidermis is dimorphic in L. pulniana stem. The stem cortex is parenchymatous comprising of fibrous idioblasts. The ground tissue is parenchymatous (L. pulniana) or sclerenchymatous (L. tenuifolia, L. tristis) containing scattered collateral vascular bundles. Xylem and phloem capped by sclerenchymatous patches. The root hairs are restricted to root regions attached to the substratum. Velamen 2–4 layered, exodermal cells with greatly thickened outer tangential walls, cover cells present. Endodermis O-thickened, vascular cylinders 15–23 arched. Mycorrhizal fungi entered roots through the root hairs and formed pelotons in the root cortex. The anatomical characteristics varied significantly among the Luisia species. Some of these anatomical features relate Luisia with epiphytic and xerophytic habitats.

Comparative leaf micromorphology and anatomy of the dragon tree group of Dracaena (Asparagaceae) and their taxonomic implications

Micromorphological features of the leaf epidermis and the inner structure of leaf tissues of eight arborescent taxa of the genus Dracaena were analysed using light and scanning electron microscopy. The plants are xeromorphic or mesomorphic. Their leaves are isobilateral and amphistomatic, and the stomata are anomocytic and tetracytic. The mesophyll in all the species is divided into an outer chlorenchyma and a central region with colourless water-storage cells, chlorophyll cells and vascular bundles. Water-storage cells have wall bands and reticulate thickenings on the walls. The article describes and illustrates several new quantitative and qualitative leaf characters of the dragon tree group. Our findings can be used to identify the dragon tree group leaves, while the shape of epidermal cells and stomata types may be useful in the identification and classification of fragments of fossil leaves. We conclude that D. ombet and D. schizantha are not two distinct species, but should be treated as subspecies of D. ombet. Leaf characters, especially stomata depth on adaxial epidermis, height of adaxial epidermal cells and the presence and thickness of hypodermal fibre bundles markedly differ between geographical groups: Macaronesian species (D. draco and D. tamaranae), the species found in East Africa and Arabian Peninsula (D. ombet subsp. ombet, D. ombet subsp. schizantha, D. serrulata and D. cinnabari) and Southeast Asian species (D. kaweesakii and D. jayniana).

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.

Comparative vegetative anatomy of South Indian Vandas (Orchidaceae)

Anatomical information serves as an important tool in identifying plants at their vegetative stage. The leaf, stem and root anatomy of Vanda spathulata (L.) Spreng., Vanda tessellata (Roxb.) Hook. ex G.Don, Vanda testacea (Lindl.) Rchb.f., and Vanda wightii Rchb.f., belonging to the tribe Vandeae in subfamily Epidendroideae were examined using different staining techniques. The important characters are as follows: the leaves have a cuticle, but the distribution and type of stomata vary. Epidermal cells are isodiametric on both the leaf surfaces. The hypodermis varies with species. The mesophyll is homogenous and vascular bundles are collateral. The stems have cuticularized epidermis with a homogenous ground tissue and scattered vascular bundles. Raphides are present in the stems of V. tessellata and V. testacea. The velamen in roots of all the Vanda species have cells with spirally thickened walls. Exodermal cells are long and dimorphic. The multi-layered parenchymatous cortex contains fungal pelotons, water-storage cells, and aeration cells. A cover layer envelops the uniseriate endodermis in V. tessellata and V. testacea. The vascular cylinders are 12–20 arched. Xylem and phloem are embedded in sclerenchymatous tissues. Parenchymatous cells of leaf, stem, and root of V. wightii contain reniform starch grains. The size of the root regions and cells are significantly variable among the Vandas. A simple dichotomous key based on the leaf and root anatomical characters for the identification of the south Indian Vanda species is provided.

Studies on some anatomical features of selected plant species grown in sand dune areas of North Sinai, Egypt

The present investigation aims at studying some anatomical features of some selected native plant species in arid environments of sand dunes at North Sinai, Egypt. Plant samples were collected from three localities; Coastal sand dunes of Balouza (Zygophyllum album, Zygophyllaceae; root, stem and leaf); sand sheets of El-Arish city (stems of Anabasis articulata, Amaranthaceae and Salsola tetrandra, Chenopodiaceae) and El-Owga interdune areas (Fagonia indica, Zygophyllaceae; stem and root, Zygophyllum album, stem). Anatomical adaptations in leaves of Zygophyllum album include the presence of palisade layers on the adaxial and abaxial surfaces, thick cuticle layer cover the epidermis, spongy mesophyll and the presence of water storage cells. Stem anatomical adaptations in different plant species as general observations were the presence of thick cuticle, multiepidermal layers, palisade shape chlorenchyma, patches of sclerenchymatous fiber in the cortex and the precipitation of raphid and druse crystals of different sizes in plant tissues. Root adaptations in Zygophyllum album and Fagonia indica include the presence of periderm layers composed of compacted and elongated cells of different origins and increase the number of small xylem vessels which can guarantee the continuity of water uptake from soil in the case of xylem embolism.

Morphology, anatomy and mycotrophy of pseudobulb and subterranean organs in Eulophia epidendraea and Malaxis acuminata (Epidendroideae, Orchidaceae)

The pseudobulbs and subterranean organs (roots and rhizomes) of Eulophia epidendraea, and Malaxis acuminata in subfamily Epidendroideae (Orchidaceae) were investigated to determine morphology, anatomy and mycorrhizal occurrence. The examined sections showed the following common anatomical characteristics. The pseudobulbs had a uniseriate epidermis. The assimilatory cells were scattered in the form of mucilage/water storage cells in the ground tissue. The vascular bundles were collateral and embedded in the ground tissue. Raphides occurred as idioblasts. Rhizomes had an uniseriate epidermis, parenchymatous ground tissue differentiated into outer and inner zones with polygonal intercellular spaces. Vascular bundles scattered, collateral and discontinuous form in both the taxa. Aeration cells were present in roots and rhizomes of M. acuminata. The transverse section of E. epidendraea roots had multi-layered velamen with spiral thickening followed by uniseriate exodermis with passage cells that had webbed tilosomes. The parenchymatous cortex contained raphides and water storage cells. Vascular bundles were 11–15 arched. Roots of M. acuminata had an uniseriate velamen, exodermis, parenchymatous cortex, endodermis and pericycle. The vascular bundles were radially arranged, and 11–12 arched. The xylem and phloem were embedded in sclerenchymatous tissue. The entry of the mycorrhizal fungi was chiefly through root hairs in roots and epidermis in rhizomes of M. acuminata, and in E. epidendraea. Fungi formed pelotons in both the taxa and microsclerotia and monilioid cells in the root cortex of E. epidendraea. Additionally, Glomus- type vesicles were occasionally present in the roots of M. acuminata. Description of characteristics arising from this investigation may provide additional morphological and anatomical means of identification.

Comparative anatomy and DNA fingerprinting of two species of the genus Ceratostylis Bl. (Orchidaceae) from North-East India with their adaptive significance

Taxonomic classification of the family Orchidaceae are generally based on morphological features and the floral attributes. At this juncture, a general query arises when species with morphological variations are placed under the same genera at times. This has triggered investigations towards comparative study on anatomy and genetic polymorphism. Anatomical studies of stem and leaf was carried out for the first time in two species of Ceratostylis Bl. viz., C. himalaica Bl. and C. subulata Hk. f. which are distributed in North-East India. Anatomical features like cuticle, epidermal layer, stomata, water storage cells, mesophyll, shape and arrangement of vascular bundles of both the species were comparatively studied. Cellulose wall of water storage cells with banded thickenings were observed in C. himalaica, whereas banded and mesh like thickenings were found in C. subulata. The water storage cells were larger in C. subulata. Anisocytic and paracytic stomata were observed in C. subulata but C. himalaica possess only paracytic type. Inter- simple sequence repeats (ISSR) analysis using 17 different primers showed differential banding patterns in the DNA fingerprint of the two orchid species with commendable polymorphism which helped in differentiating the two species at genomic level. This study shows that the significant differences between the two species in relation to their morphological appearance, internal structures and genetic polymorphism throws an insight towards a better understanding of their divergent adaptation and genetic diversity which is beneficial for the conservation of these two species.

One-Pot Synthesis of Elastomeric Monoliths Filled with Individually Encapsulated Liquid Droplets

The ability to encapsulate and store liquids within discrete, micrometer-scale containers is essential for living organisms and is used by water-storage cells to keep plants healthy, even during a prolonged drought. This paper describes the one-pot synthesis of liquid droplet elastomers (LDEs), a novel materials system with advantageous properties. LDEs are tissue-like elastomeric monoliths that contain around 85% water in the form of individually encapsulated micrometer-scale droplets. The LDE structure is templated within high internal phase Pickering emulsions, emulsions stabilized by nanoparticles that also function as cross-linking centers. The polyhedral shapes of the droplets, which accommodate the high volume fraction of water, are “locked-in” to the LDE during polymerization. The water retention in these unique materials is exceedingly high, and as seen for living systems, the presence of the encapsulated water droplets enhances the resistance to compressive deformation and to ignition upon direct exposure to a flame.

Anatomical Adaptations of Boerhavia L. and Commicarpus Standl. (Nyctaginaceae) for Survival in Arid Environments of Namibia

Members of the Nyctaginaceae Jussieu. are distributed throughout southern Africa. Eight species of the family occur naturally in arid parts of Namibia. These species have acquired the ability to survive and reproduce in these dry conditions. They are xerophytes, which have been described as drought evaders, avoiders, and drought-tolerant. In the Nyctaginaceae, Boerhavia deserticola, B. hereroensis, Commicarpus helenae and C. squarrosus are thought to be drought avoiders. In this study we investigated their stem, leaf and anthocarp anatomy for adaptations to arid environments. The results indicated that the four species are avoiders, with modifications of the trichomes, secretions, crystals, secondary growth, Kranz mesophyll, water storage cells, tannins, mucilage, inner and outer stomatal ledges, large-diameter xylem vessels, and the presence of sclerenchyma in their stems, leaves and anthocarps. These adaptations enable the plants to tolerate arid conditions, conserve water and maintain a high photosynthetic rate, and aid seed dispersal.