scholarly journals RESILIENCE OF FERNS: WITH REFERENCE TO DESICCATION AND REHYDRATION STRESS OFFER NEW INSIGHTS

2017 ◽  
Vol 4 (2) ◽  
pp. 89-94
Author(s):  
Kavitha C.H ◽  
Meenu Krishnan ◽  
Murugan K
Keyword(s):  
Vascular Plants ◽  
Stress Proteins ◽  
Secondary Xylem ◽  
Plant Water Relations ◽  
Vascular Bundles ◽  
Late Cenozoic ◽  
Primary Xylem ◽  
Hydraulic Failure ◽  
Pit Membrane ◽  
Selection For

Ferns are one of the oldest vascular plants in existence and they are the second most diverse group of vascular plants followed to angiosperms. To unravel fern success has focused on the eco-physiological power and stress tolerance of their sporophyte and the gametophyte generations. In this context, those insightsencompass plant water relations, as well as the tolerance to and recovery from drought or desiccation stresses in the fern life cycle are reviewed. Lack of secondary xylem in ferns is compensated by selection for efficient primary xylem composed of large, closely arranged tracheids with permeable pit membranes.Protection from drought-induced hydraulic failure appears to arise from a combination of pit membrane traits and the arrangement of vascular bundles. Features such as tracheid-based xylem and variously sized megaphylls are shared between ferns and more derived lineages, and offer an opportunity to compare convergent and divergent hydraulic strategies critical to the success of xylem-bearing plants. Similarly the synthesis and accumulation of sugar, proline and stress proteins along with the production of pool of polyphenols add strength to desiccation stress. Thus, it can possible to suggest that selection acted on the physiology in a synchronous manner that is consistent with selection for drought tolerance in the epiphytic niche, and the increasingly diverse habitats of the mid to late Cenozoic.

scholarly journals The stem anatomy of the Clematis species (Ranunculaceae) in Taiwan

2021 ◽  
Author(s):  
Sheng-Zehn Yang ◽  
Po-Hao Chen ◽  
Chien-Fan Chen
Keyword(s):  
Secondary Xylem ◽  
Secondary Growth ◽  
Restriction Pattern ◽  
Vascular Bundles ◽  
Stem Anatomy ◽  
Primary Xylem ◽  
Morphological Studies ◽  
Arc Shape ◽  
Key Features ◽  
Cambial Variants

Abstract Background Studies on the stem anatomical characteristics of Taiwanese species from the Clematis genus (Ranunculaceae) are scarce. This study aimed to investigate and compare the patterns of secondary growth in stems of 22 Clematis species. Results The rhytidome is composed of periderm and non-conducting phloem and formed either cogwheel-like or continuous segment bark. Key features of the genus were stem with an irregular conformation, wedge-like phloem and rays, indentations in the axial parenchyma, ray dilatation, and narrow rays. Approximately eight Clematis species formed bark arc shape, which developed the cogwheel- like rhytidome. There were with approximately 27% of the Clematis species in Taiwan having 12 vascular bundles. The vessels dispersed throughout the stem were semi-ring-porous in most species but were ring-porous in others. No species had diffuse-porous vessels. The vessel restriction pattern was only found in the two shrubs, C. psilandra and C. tsugetorum. The primary xylem ring was located around the pith in C. uncinata var. uncinata, making its pith cavity hexagon in shape. Four species had the pith cavity feature. Narrow rays that occurred in the secondary xylem increased with increasing stem diameter. Conclusions The cambial variants described in this study provide a foundation for further morphological studies of the Clematis genus.

scholarly journals Bark and Cambial Variation in the Genus Clematis (Ranunculaceae) in Taiwan

2020 ◽  
Author(s):  
Sheng-Zehn Yang ◽  
Po-Hao Chen ◽  
Chien-Fan Chen
Keyword(s):  
Vascular Bundle ◽  
Secondary Xylem ◽  
Vascular Bundles ◽  
Outer Bark ◽  
Axial Parenchyma ◽  
Primary Xylem ◽  
Second Stage ◽  
Morphological Studies ◽  
Key Features ◽  
Sclerenchyma Fibers

Abstract BackgroundStudies on the anatomical characteristics of stems of Taiwanese species from the Clematis genus (Ranunculaceae) are scarce. The aim of this study was to investigate and compare cambial variation in stems of 22 Clematis species. ResultsThe rhytidome (outer bark) was either cogwheel-like or continuous, except for in the species Clematis tashiroi. Key features of the genus were eccentric to elliptical or polygonous-lobed stems, wedge-like phloem, wedge-like rays, indentations in the axial parenchyma, and ray dilatation. The cortical sclerenchyma fibers were embedded in the phloem rays with approximately 23% of the Clematis species. Both C. psilandra and C. tsugetorum had restricted vessels. There were three vascular bundle patterns, with approximately 27% of the Clematis species in Taiwan having 12 vascular bundles. The vessels dispersed throughout the stem were semi-ring-porous in most species, but were ring-porous in others. No species had diffuse-porous vessels. Only two species had a primary xylem ring located around the pith. Secondary xylem rays split the secondary xylem into parts, increasing stem diameter. The developmental stage of each sample was determined, with the initial ring-like periderm being produced in the primary phloem during the second stage. ConclusionsThe cambial variations described in this study provide a foundation for further morphological studies of the Clematis genus.

Pentaphragma: A Unique Wood and its Significance

IAWA Journal ◽  
1997 ◽  
Vol 18 (1) ◽  
pp. 3-12 ◽  
Author(s):  
Sherwin Carlquist
Keyword(s):  
Secondary Xylem ◽  
Lateral Wall ◽  
Qualitative And Quantitative ◽  
Primary Xylem ◽  
Pit Membrane ◽  
Bordered Pits ◽  
Vessel Elements ◽  
Perforation Plates ◽  
Secondary Woodiness ◽  
Basal Position

Qualitative and quantitative data are given for wood anatomy of three species of Pentaphragma (Pentaphragmataceae); the woods of the three species are very similar. Pentaphragma is rayless, but eventually develops rays in at least one of the species studied. This is interpreted as related to secondary woodiness or upright habit within a predominantly herbaceous phylad. The vessel elements of Pentaphragma have features universally interpreted as primitive in dicotyledons: scalariform perforation plates with numerous bars; pit membrane remnants in perforations; scalariform lateral wall pitting; the genus also has fiber-tracheids with prominently bordered pits. These character states accord with the basal position in Campanulales accorded Pentaphragmataceae by Cosner et al. (1992), and suggests that order may have begun with more numerous primitive features than generally recognized. The presence of occasional scalariform perforation plates, often aberrant, in secondary xylem of families of Asterales sensu lato - Campanulaceae, Pentaphragmataceae, Valerianaceae, and even Asteraceae (e.g., certain Lactuceae) - can be attributed to paedomorphosis, extending these plates into secondary xylem from primary xylem. Raylessness in Pentaphragma can be described in terms of secondary woodiness or paedomorphosis. The fact that fiber-tracheids are shorter than vessel elements in Pentaphragma is believed related to raylessness also, because some fiber-tracheids are produced from 'potential' ray areas.

scholarly journals Anatomy of Brazilian Cereeae (subfamily Cactoideae, Cactaceae): Arrojadoa Britton & Rose, Stephanocereus A. Berger and Brasilicereus Backeberg

2007 ◽  
Vol 21 (4) ◽  
pp. 813-822 ◽  
Author(s):  
Patricia Soffiatti ◽  
Veronica Angyalossy
Keyword(s):  
Secondary Xylem ◽  
Sieve Tube ◽  
Vascular Bundles ◽  
Campos Rupestres ◽  
Espinhaço Range ◽  
Diagnostic Characters ◽  
Bordered Pits ◽  
Companion Cells ◽  
Southern Bahia ◽  
Perforation Plates

(Anatomy of Brazilian Cereeae (subfamily Cactoideae, Cactaceae): Arrojadoa Britton & Rose, Stephanocereus A. Berger wâBrasilicereus Backeberg). Arrojadoa, Stephanocereus and Brasilicereus are endemic Brazilian Cereeae, occurring along the Espinhaço Range, in the campos rupestres, cerrados and caatingas, from northern Minas Gerais to southern Bahia. The genera are columnar, erect to semi-erect cacti, except for one species, A bahiensis, which is globose. This study describes the anatomy of dermal, fundamental and vascular systems, aiming to find diagnostic characters for the genera and species. Basal portions of stems were sectioned transversely and longitudinally, and stained with Astrablue and Safranin. The species share a uniseriate epidermis, with thick cuticle; well developed collenchymatic hypodermis, containing prismatic crystals; cortex with numerous mucilage cells, druses and vascular bundles; outside cortex as a palisade parenchyma; periderm composed of lignified cork cells alternating with suberized cells; pheloderm consisting of a few layers of thin-walled cells; phloem composed of solitary or multiple of two to three sieve tube elements, companion cells, axial and radial parenchyma; secondary xylem with solitary to multiple vessels, with simple perforation plates and alternate bordered to semi-bordered pits; axial parenchyma scanty vasicentric to incomplete; libriform septate fibres; large rays. Unlignified parenchyma is seen in the secondary xylem, varying from a few cells to bands among axial and radial elements. The following are considered diagnostic characters: the shape of lignified phellem cells, cubic to radially elongate, which individualizes S. leucostele; an underdeveloped hypodermis and the occurrence of sclereids in the cortex are exclusive to Brasilicereus markgrqfii.

Structure of the Vessel-Parenchyma Pit Membrane in Some Species of Lauraceae

IAWA Journal ◽  
1985 ◽  
Vol 6 (1) ◽  
pp. 35-38 ◽  
Author(s):  
María Agueda Castro
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Secondary Xylem ◽  
Pit Membrane ◽  
Scanning Electron

The structure of the vessel-parenchyma pit membranes in the secondary xylem of seven species of Lauraceae has been studied with scanning electron microscopy (SEM).

scholarly journals WOOD ANATOMY OF THE VANGUERIEAE (IXOROIDEAERUBIACEAE), WITH SPECIAL EMPHASIS ON SOME GEOFRUTICES

IAWA Journal ◽  
2000 ◽  
Vol 21 (4) ◽  
pp. 443-455 ◽  
Author(s):  
Frederic Lens ◽  
Steven Jansen ◽  
Elmar Robbrecht ◽  
Erik Smets
Keyword(s):  
Pacific Ocean ◽  
Wood Anatomy ◽  
Secondary Xylem ◽  
Vessel Diameter ◽  
Underground Structures ◽  
Axial Parenchyma ◽  
Tropical Asia ◽  
Primary Xylem ◽  
The Pacific ◽  
The Pacific Ocean

The Vanguerieae is a tribe consisting of about 500 species ordered in 27 genera. Although this tribe is mainly represented in Africa and Madagascar, Vanguerieae also occur in tropical Asia, Australia, and the isles of the Pacific Ocean. This study gives a detailed wood anatomical description of 34 species of 15 genera based on LM and SEM observations. The secondary xylem is homogeneous throughout the tribe and fits well into the Ixoroideae s.l. on the basis of fibre-tracheids and diffuse to diffuse-in-aggregates axial parenchyma. The Vanguerieae include numerous geofrutices that are characterised by massive woody branched or unbranched underground parts and slightly ramified unbranched aboveground twigs. The underground structures of geofrutices are not homologous; a central pith is found in three species (Fadogia schmitzii, Pygmaeothamnus zeyheri and Tapiphyllum cinerascens var. laetum), while Fadogiella stigmatoloba shows central primary xylem which is characteristic of roots. Comparison of underground versus aboveground wood shows anatomical differences in vessel diameter and in the quantity of parenchyma and fibres.

scholarly journals Development of successive cambia and wood structure in stem of Rivea hypocriteriformis (Convolvulaceae)

2016 ◽  
Vol 61 (1) ◽  
pp. 89-98 ◽  
Author(s):  
Kishore S. Rajput
Keyword(s):  
Secondary Xylem ◽  
Monsoon Season ◽  
Secondary Growth ◽  
Vascular Bundles ◽  
Growth Rings ◽  
Successive Cambia ◽  
Initial Stage ◽  
Ray Cells ◽  
Cell Layers ◽  
Ray Parenchyma Cells

Abstract This study examined the formation of successive rings of cambia in Rivea hypocriteriformis Choisy (Convolvulaceae). The mature stem is composed of four to five rings of xylem alternating with phloem. Successive cambia originate as smaller and larger segments; union and anastomosing of small cambial segments often leads to the formation of discontinuous rings. In the initial stage of growth, several vascular bundles interconnect to form the first ring of vascular cambium. The cambium remains functional for one complete season and becomes dormant during summer; a new ring of cambium is completed prior to the subsequent monsoon season and sprouting of new leaves. Successive cambia are initiated from the pericyclic parenchyma situated three to four cell layers outside of the protophloem. Functionally, all the successive cambia are bidirectional and produce secondary xylem centripetally and phloem centrifugally. The secondary xylem is diffuse-porous, with indistinct growth rings and consisting of wide fibriform vessels, fibre tracheids, and axial and ray parenchyma cells. The xylem rays are uni- to multiseriate and heterocellular. The multiseriate rays contain lignified marginal ray cells and thin-walled, unlignified central cells. The central ray cells also show accumulations of starch and druses. Discrete strands of intraxylary phloem occur at the periphery of the pith, and additional intraxylary phloem develops from adjacent cells as secondary growth progresses. Earlier-formed phloem shows heavy accumulation of callose, followed by its compaction. The development of successive cambia is correlated with extension growth and with the phenology of the plant.

Surgical studies on growth and xylem differentiation in the cotyledonary shoots of flax

1978 ◽  
Vol 56 (5) ◽  
pp. 476-482 ◽  
Author(s):  
M. V. S. Raju ◽  
W. N. Marchuk ◽  
Patricia L. Polowick
Keyword(s):  
Linum Usitatissimum ◽  
Secondary Xylem ◽  
Xylem Differentiation ◽  
Primary Xylem ◽  
The Third ◽  
Lateral Shoots

Growth and xylem differentiation in cotyledonary shoots were studied by partially isolating one shoot surgically in nondecapitated and decapitated flax plants (Linum usitatissimum var. noralta). Three types of cuts were made. The first type separated the shoot from the hypocotyl and the second from the epicotyl. The third type of cut was made at the node separating the two shoots, which, however, remained independently connected with the hypocotyl and epicotyl. In nondecapitated plants, the lateral shoots were inhibited. They had at their bases primary xylem strands, some of which were connected with the hypocotylary stele; the strands contained predominantly tracheids. In decapitated plants, the separated shoot grew vigorously when it was connected with both hypocotyl and epicotyl or hypocotyl alone. Such shoots contained at their bases abundant secondary xylem strands which were connected with the hypocotylary stele; the strands included predominantly vessels. The shoot that was isolated from the hypocotyl but connected with the epicotyl was inhibited even though it had abundant secondary xylem strands at its base. Results of this study suggest that growth of the cotyledonary shoot is dependent on the prior development of adequate xylem connections with the hypocotylary stele.

scholarly journals Silene thymifolia Sibth. et Sm. (Caryophyllaceae) – A vulnerable species in Romania: Anatomical aspects of vegetative organs

2021 ◽  
Vol 13 (1) ◽  
pp. 10875
Author(s):  
Loreley D. JIANU ◽  
Rodica BERCU ◽  
Dan R. POPOVICIU
Keyword(s):  
Cross Section ◽  
Secondary Xylem ◽  
Coastal Dunes ◽  
Vascular Bundles ◽  
Vulnerable Species ◽  
Spongy Tissue ◽  
Specific Staining ◽  
Vegetative Organs ◽  
Glandular Hairs ◽  
Near Threatened

Silene thymifolia (Caryophyllaceae) is considered a rare, near-threatened species in Romania, growing only on Black Sea coastal dunes.  Anatomical aspects of the root, stem and leaf of this species are presented in this study. Root, stem and leaves were analysed by brightfield microscopy, with specific staining. The root in cross section exhibited a secondary structure, generated by the activity of phellogen, and vascular cambium, with thick cork, continuous secondary xylem rings. no pith rays, but with cortical air lacunes. The stem had a primary structure with a number of collateral vascular bundles arranged on a single circle, with thick cortical schlerenchymal layers and oxalate crystals in pith cells. The epidermis showed stomata and glandular hairs. The leaf was amphystomatic leaf, with a heterogeneous mesophyll (equifacial type) and embedded vascular bundles, with a rounded mid rib surrounded by a parenchyma sheath. The spongy tissue has some large intercellular air spaces with druses. The mechanical tissue is well developed in the root and stem and poorly developed, represented by few collenchyma elements in the mesophyll, being represented by a continuous schlerenchyma fibers band present in root and stem and collenchyma in the leaf. The secretory histological elements were represented by epidermal glandular hairs and oxaliferous cells (druses) present in stem and leaf.

scholarly journals Learning from the past – the origin of wood

2008 ◽  
Vol 84 (4) ◽  
pp. 498-503 ◽  
Author(s):  
Rodney Arthur Savidge
Keyword(s):  
Cell Biology ◽  
Secondary Xylem ◽  
Secondary Growth ◽  
Wood Formation ◽  
Late Triassic ◽  
Primary Xylem ◽  
Tree Ferns ◽  
Severe Climate Change ◽  
Middle Carboniferous ◽  
Extinction Events

Trees were on Earth 394 million years ago (394 Ma) as spore-producing Archaeopteris progymnosperms having largediameter trunks of secondary xylem (morphotype Callixyon) produced by vascular cambium. Plants of smaller stature with primary xylem cores were present in Late Silurian (416 Ma), but they lacked cambium and it remains unclear how and when the first trees evolved. Progymnosperms faded and gymnosperms arose during Middle Carboniferous, and conifers, ginkgos, cycads, tree ferns and cordaites were well established by the Carboniferous–Permian transition (299 Ma). Woods of the earliest conifers were different from those of today, and not until Late Triassic (220 Ma) did any begin producing secondary xylem similar to modern woods, the xylem phenotypes of Cupressaceae and Araucariaceae emerging much earlier than those of Pinaceae and flowering plants. Conifers have persisted and done relatively well despite major extinction events, severe climate change, insectivory, herbivory and microbial activity, all of which were in effect before as well as during the appearance of trees on Earth. Approximately 600 conifer species continue to exist, and the survivors presumably possess the physiological fitness needed to adapt to an ever-changing biosphere. However, this is speculative because their physiology remains less than well understood. Forestry interventions such as planting one species to the exclusion of others have the potential to exacerbate as well as sustain the ongoing existence of our remaining conifers. Key words: bordered pit, cambium, cell biology, cellulose, evolution, lignin, paleobotany, protoplasmic autolysis, secondary growth, wood formation, xylogenesis

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