DOCSLIB.ORG

Ground Tissue System –

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Ground Tissue System – 4/3/2014 BI 103: Laboratory 1 Plant tissues & morphology Tissues & Organs I. Plants have three -four major groups of organs: 1. Roots 2. Stems 3. Leaves 4. Flowers II. Each organ is composed of tissues. A tissue is a group of cells performing a similar function. 1 4/3/2014 Plant Anatomy: Vegetative Organs Leaves: Stem: Arise from stem Place leaves, buds, & roots attach Roots: Arise from stem Plant Anatomy: Vegetative Organs Leaves: Stem: Photosynthesis Support Gas exchange Transport Light absorption Storage Roots: Anchorage Storage Form = Function Transport Absorption 2 4/3/2014 Kale Broccoli Wild Brassica oleracea Cauliflower Cabbage Kohlrabi Brussels sprouts Plant Organs: human cultivation and manipulation 3 4/3/2014 Plant Anatomy: Tissues 4 Tissues: 1. Meristematic 2. Ground 3. Vascular 4. Dermal Plant Growth Meristems – Tissues of plants that add new growth. Regions of actively dividing cells. Apical – increases length/height (primary) Lateral – increases girth. (secondary) 4 4/3/2014 Plant Anatomy: Tissues and Cells Meristematic Tissue Apical Pericycle Vascular Cork Meristem Cambium Cambium Functions of Meristematic Tissue: • Growth • Primary (length) • Secondary (girth) Apical Growth Root: pericycle Shoot: Apical meristem 5 4/3/2014 Apical Meristem Aka lateral buds Leaf Apical Primordia Meristem Older Leaf Primordia Axillary Bud (developing) Primordia 6 4/3/2014 Old Tjikko– can trees live forever? 9,550 yrs old root system Norway spruce in Sweden Trunk itself only ~700 yrs old Secondary Growth 7 4/3/2014 Types of Tissues Dermal tissue system – protects plant Ground tissue system – Vascular tissue – Tissues and Cells Epidermal Tissue Epidermis Guard Trichomes Root hairs Cells Functions of Dermal Tissue: • Protection • Regulates movement of materials Trichomes: 8 4/3/2014 Dermal Tissues I. Cuticle – waxy coating II. Epidermis – for outer layer III. Trichomes – Hairs for preventing water loss. IV. Periderm – outer bark V. Guard cells & Stomata Guard Cells 9 4/3/2014 Types of Tissues Dermal tissue system – protects plant Ground tissue system – Provides support, stores starch, and carries out photosynthesis. Vascular tissue – Tissues and Cells Ground Tissue Parenchyma Collenchyma Sclerenchyma Flexible Rigid Large cell Small Cell Thin cell wall Thickest cell wall Functions of Ground Tissue: • Support: water filled vacuoles • Storage: starch • Photosynthesis 10 4/3/2014 Ground tissue Parenchyma cells: • Majority of cells in the plant. • Thin, pliable walls • Large vacuoles and various secretions Parenchyma cells • These cells photosynthesize in leaves. • Living Tissues and Cells: Ground Tissue In Roots: Parenchyma Parenchyma contain extra In Leaf: starch in the In Stem: Mesophyll cells cortex for storage Parenchyma form Contain lots of pith for support chloroplasts for photosynthesis 11 4/3/2014 Ground tissue Collenchyma cells: • Cell walls moderately thick • Flexible support Collenchyma cells • Living cells Ground tissue Sclerenchyma tissue - • Thick, tough, secondary walls, normally impregnated with lignin Sclereids • Function in support • Dead at maturity Two types: • Sclereids - Stone Cells • Fibers- long and thin 12 4/3/2014 Sclereids Fibers: • Sclereids - Stone Cells • Fibers- long and thin Types of Tissues Dermal tissue system – protects plant Ground tissue system – Provides support, stores starch, and carries out photosynthesis. Vascular tissue – Conducts fluids and helps strengthen roots, stems and leaves. 13 4/3/2014 Tissues and Cells Vascular Tissue Tracheids Vessel Sieve Tube Companion Elements Members Cells Xylem Phloem Functions of Vascular Tissue: • Transport • Support Vascular Tissue I. Xylem – water & minerals conducting pipes. --Wood is mostly xylem, -- dead at maturity II. Phloem – transports sugars & hormones -- Sap runs through phloem 14 4/3/2014 Complex plant conducting tissues > xylem >phloem a young corn stem is shown here. Secondary Growth 15 .
Load more

Recommended publications
  • Parenchyma Cell Respiration and Survival in Secondary Xylem: Does Metabolic Activity Decline with Cell Age?
    Plant, Cell and Environment (2007) 30, 934–943 doi: 10.1111/j.1365-3040.2007.01677.x Parenchyma cell respiration and survival in secondary xylem: does metabolic activity decline with cell age? R. SPICER1 & N. M. HOLBROOK2 1Rowland Institute at Harvard University, 100 Edwin H. Land Boulevard, Cambridge, MA 02142, USA and 2Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA ABSTRACT defines (and arguably drives) heartwood formation, a form of tissue senescence during which the oldest, non- Sapwood respiration often declines towards the sapwood/ functional xylem is compartmentalized in the centre of the heartwood boundary, but it is not known if parenchyma stem. The cause of parenchyma cell death is not known, metabolic activity declines with cell age. We measured but evidence for decreased metabolic activity in the inner- sapwood respiration in five temperate species (sapwood age most sapwood has led to a view of parenchyma ageing as range of 5–64 years) and expressed respiration on a live cell a gradual, passive decline in metabolism that terminates in basis by quantifying living parenchyma. We found no effect cell death. of parenchyma age on respiration in two conifers (Pinus Multiple reports suggest that sapwood respiration strobus, Tsuga canadensis), both of which had signifi- declines towards the sapwood/heartwood boundary cant amounts of dead parenchyma in the sapwood. In (Goodwin & Goddard 1940; Higuchi, Shimada & Watanabe angiosperms (Acer rubrum, Fraxinus americana, Quercus 1967; Pruyn, Gartner & Harmon 2002a,b; Pruyn, Harmon & rubra), both bulk tissue and live cell respiration were Gartner 2003; Pruyn, Gartner & Harmon 2005), although reduced by about one-half in the oldest relative to the there have been reports of no change (Bowman et al.
    [Show full text]
  • Does the Distance to Normal Renal Parenchyma (DTNRP) in Nephron-Sparing Surgery for Renal Cell Carcinoma Have an Effect on Survival?
    ANTICANCER RESEARCH 25: 1629-1632 (2005) Does the Distance to Normal Renal Parenchyma (DTNRP) in Nephron-sparing Surgery for Renal Cell Carcinoma have an Effect on Survival? Z. AKÇETIN1, V. ZUGOR1, D. ELSÄSSER1, F.S. KRAUSE1, B. LAUSEN2, K.M. SCHROTT1 and D.G. ENGEHAUSEN1 Departments of 1Urology and 2Medical Informatics, Biometry and Epidemiology, University of Erlangen-Nuremberg, Germany Abstract. Background: The effect of the distance to normal renal solitary kidneys. Additionally, organ preservation in the parenchyma (DTNRP) on survival after nephron-sparing surgery presence of an intact contralateral kidney can be performed (NSS) for renal cell cancer (RCC) was analyzed. Additionally, for small localized tumors with nearly equivalent results for the role of T-classification, tumor diameter and tumor grading tumor-specific survival, compared to nephrectomy (1). The was considered. Patients and Methods: NSS was performed on question of whether a small safety margin in intraoperative 126 patients with RCC between 1988 and 2000. Eighty-six patients histology may be adequate for favorable outcome of the were submitted to annual follow-up. These 86 patients were sub- patient constitutes an everyday issue for the practitioner classified into statistical groups according to the distance performing nephron-sparing surgery. In this context, the to normal renal parenchyma (≤ 2mm; > 2mm – ≤ 5mm; clinical impact of defined surgical margin widths for >5 mm), T-classification, tumor diameter (≤ 20mm; > 20mm - avoiding local tumor recurrence and, therefore, improved ≤ 30 mm; >30 mm – ≤ 50mm; >50mm) and tumor grading. survival after nephron-sparing surgery has been discussed The effect of belonging to one of these groups on survival was but still remains controversial.
    [Show full text]
  • Tissues and Other Levels of Organization MODULE - 1 Diversity and Evolution of Life
    Tissues and Other Levels of Organization MODULE - 1 Diversity and Evolution of Life 5 Notes TISSUES AND OTHER LEVELS OF ORGANIZATION You have just learnt that cell is the fundamental structural and functional unit of organisms and that bodies of organisms are made up of cells of various shapes and sizes. Groups of similar cells aggregate to collectively perform a particular function. Such groups of cells are termed “tissues”. This lesson deals with the various kinds of tissues of plants and animals. OBJECTIVES After completing this lesson, you will be able to : z define tissues; z classify plant tissues; z name the various kinds of plant tissues; z enunciate the tunica corpus theory and histogen theory; z classify animal tissues; z describe the structure and function of various kinds of epithelial tissues; z describe the structure and function of various kinds of connective tissues; z describe the structure and function of muscular tissue; z describe the structure and function of nervous tissue. 5.1 WHAT IS A TISSUE Organs such as stem, and roots in plants, and stomach, heart and lungs in animals are made up of different kinds of tissues. A tissue is a group of cells with a common origin, structure and function. Their common origin means they are derived from the same layer (details in lesson No. 20) of cells in the embryo. Being of a common origin, there are similar in structure and hence perform the same function. Several types of tissues organise to form an organ. Example : Blood, bone, and cartilage are some examples of animal tissues whereas parenchyma, collenchyma, xylem and phloem are different tissues present in the plants.
    [Show full text]
  • The Genomics of Wood Formation in Angiosperm Trees
    The Genomics of Wood Formation in Angiosperm Trees Xinqiang He and Andrew T. Groover Abstract Advances in genomic science have enabled comparative approaches that can evaluate the evolution of genes and mechanisms underlying phenotypic traits relevant to angiosperm forest trees. Wood formation is an excellent subject for com- parative genomics, as it is an ancestral trait for angiosperms and has undergone significant modification in different angiosperm lineages. This chapter discusses some of the traits associated with wood formation, what is currently known about the genes and mechanisms regulating these traits, and how comparative evolution- ary genomic studies can be undertaken to provide more comprehensive views of the evolution and development of wood formation in angiosperms. Keywords Wood formation • Wood development • Wood evolution • Transcriptional regulation • Epigenetics • Comparative genomics Genomic Perspectives on the Evolutionary Origins and Variation in Angiosperm Wood Introduction The evolutionary and developmental biology of wood are fundamental to under- standing the amazing diversification of angiosperms. While flower morphology and reproductive characters associated with angiosperms have been the focus of numer- ous genetic and genomic evo-devo studies, wood development is a relatively neglected trait of angiosperm evolution and development that is now tractable for comparative and evolutionary genomic studies. The ability to produce wood from a X. He School of Life Sciences, Peking University, Beijing 100871, China A.T. Groover (*) Pacific Southwest Research Station, US Forest Service, Davis, 95618 CA, USA Department of Plant Biology, University of California Davis, Davis, 95618 CA, USA e-mail: [email protected] © Springer International Publishing AG 2017 205 A.T. Groover and Q.C.B.
    [Show full text]
  • Squamous Cell Carcinoma of the Renal Parenchyma
    Zhang et al. BMC Urology (2020) 20:107 https://doi.org/10.1186/s12894-020-00676-5 CASE REPORT Open Access Squamous cell carcinoma of the renal parenchyma presenting as hydronephrosis: a case report and review of the recent literature Xirong Zhang1,2, Yuanfeng Zhang1, Chengguo Ge1, Junyong Zhang1 and Peihe Liang1* Abstract Background: Primary squamous cell carcinoma of the renal parenchyma is extremely rare, only 5 cases were reported. Case presentation: We probably report the fifth case of primary Squamous cell carcinoma (SCC) of the renal parenchyma in a 61-year-old female presenting with intermittent distending pain for 2 months. Contrast-enhanced computed tomography (CECT) revealed hydronephrosis of the right kidney, but a tumor cannot be excluded completely. Finally, nephrectomy was performed, and histological analysis determined that the diagnosis was kidney parenchyma squamous cell carcinoma involving perinephric adipose tissue. Conclusions: The present case emphasizes that it is difficult to make an accurate preoperative diagnosis with the presentation of hidden malignancy, such as hydronephrosis. Keywords: Kidney, Renal parenchyma, Squamous cell carcinoma, Hydronephrosis, Malignancy Background Case presentation Squamous cell carcinoma (SCC) of the renal pelvis is a The patient is a 61-year-old female. After suffering from rare neoplasm, accounting for only 0.5 to 0.8% of malig- intermittent pain in the right flank region for 2 months nant renal tumors [1], SCC of the renal parenchyma is she was referred to the urology department at an outside even less common. A review of the literature shows that hospital. The patient was diagnosed with hydronephrosis only five cases of primary SCC of the renal parenchyma of the right kidney and underwent a right ureteroscopy have been reported to date [2–6].
    [Show full text]
  • Methods for Measuring Frost Tolerance of Conifers: a Systematic Map
    Review Methods for Measuring Frost Tolerance of Conifers: A Systematic Map Anastasia-Ainhoa Atucha Zamkova *, Katherine A. Steele and Andrew R. Smith School of Natural Sciences, Bangor University, Bangor LL57 2UW, Gwynedd, UK; [email protected] (K.A.S.); [email protected] (A.R.S.) * Correspondence: [email protected] Abstract: Frost tolerance is the ability of plants to withstand freezing temperatures without unrecov- erable damage. Measuring frost tolerance involves various steps, each of which will vary depending on the objectives of the study. This systematic map takes an overall view of the literature that uses frost tolerance measuring techniques in gymnosperms, focusing mainly on conifers. Many different techniques have been used for testing, and there has been little change in methodology since 2000. The gold standard remains the field observation study, which, due to its cost, is frequently substituted by other techniques. Closed enclosure freezing tests (all non-field freezing tests) are done using various types of equipment for inducing artificial freezing. An examination of the literature indicates that several factors have to be controlled in order to measure frost tolerance in a manner similar to observation in a field study. Equipment that allows controlling the freezing rate, frost exposure time and thawing rate would obtain results closer to field studies. Other important factors in study design are the number of test temperatures used, the range of temperatures selected and the decrements between the temperatures, which should be selected based on expected frost tolerance of the tissue and species. Citation: Atucha Zamkova, A.-A.; Steele, K.A.; Smith, A.R.
    [Show full text]
  • Dicot/Monocot Root Anatomy the Figure Shown Below Is a Cross Section of the Herbaceous Dicot Root Ranunculus. the Vascular Tissu
    Dicot/Monocot Root Anatomy The figure shown below is a cross section of the herbaceous dicot root Ranunculus. The vascular tissue is in the very center of the root. The ground tissue surrounding the vascular cylinder is the cortex. An epidermis surrounds the entire root. The central region of vascular tissue is termed the vascular cylinder. Note that the innermost layer of the cortex is stained red. This layer is the endodermis. The endodermis was derived from the ground meristem and is properly part of the cortex. All the tissues inside the endodermis were derived from procambium. Xylem fills the very middle of the vascular cylinder and its boundary is marked by ridges and valleys. The valleys are filled with phloem, and there are as many strands of phloem as there are ridges of the xylem. Note that each phloem strand has one enormous sieve tube member. Outside of this cylinder of xylem and phloem, located immediately below the endodermis, is a region of cells called the pericycle. These cells give rise to lateral roots and are also important in secondary growth. Label the tissue layers in the following figure of the cross section of a mature Ranunculus root below. 1 The figure shown below is that of the monocot Zea mays (corn). Note the differences between this and the dicot root shown above. 2 Note the sclerenchymized endodermis and epidermis. In some monocot roots the hypodermis (exodermis) is also heavily sclerenchymized. There are numerous xylem points rather than the 3-5 (occasionally up to 7) generally found in the dicot root.
    [Show full text]
  • Anatomical Traits Related to Stress in High Density Populations of Typha Angustifolia L
    http://dx.doi.org/10.1590/1519-6984.09715 Original Article Anatomical traits related to stress in high density populations of Typha angustifolia L. (Typhaceae) F. F. Corrêaa*, M. P. Pereiraa, R. H. Madailb, B. R. Santosc, S. Barbosac, E. M. Castroa and F. J. Pereiraa aPrograma de Pós-graduação em Botânica Aplicada, Departamento de Biologia, Universidade Federal de Lavras – UFLA, Campus Universitário, CEP 37200-000, Lavras, MG, Brazil bInstituto Federal de Educação, Ciência e Tecnologia do Sul de Minas Gerais – IFSULDEMINAS, Campus Poços de Caldas, Avenida Dirce Pereira Rosa, 300, CEP 37713-100, Poços de Caldas, MG, Brazil cInstituto de Ciências da Natureza, Universidade Federal de Alfenas – UNIFAL, Rua Gabriel Monteiro da Silva, 700, CEP 37130-000, Alfenas, MG, Brazil *e-mail: [email protected] Received: June 26, 2015 – Accepted: November 9, 2015 – Distributed: February 28, 2017 (With 3 figures) Abstract Some macrophytes species show a high growth potential, colonizing large areas on aquatic environments. Cattail (Typha angustifolia L.) uncontrolled growth causes several problems to human activities and local biodiversity, but this also may lead to competition and further problems for this species itself. Thus, the objective of this study was to investigate anatomical modifications on T. angustifolia plants from different population densities, once it can help to understand its biology. Roots and leaves were collected from natural populations growing under high and low densities. These plant materials were fixed and submitted to usual plant microtechnique procedures. Slides were observed and photographed under light microscopy and images were analyzed in the UTHSCSA-Imagetool software. The experimental design was completely randomized with two treatments and ten replicates, data were submitted to one-way ANOVA and Scott-Knott test at p<0.05.
    [Show full text]
  • Eudicots Monocots Stems Embryos Roots Leaf Venation Pollen Flowers
    Monocots Eudicots Embryos One cotyledon Two cotyledons Leaf venation Veins Veins usually parallel usually netlike Stems Vascular tissue Vascular tissue scattered usually arranged in ring Roots Root system usually Taproot (main root) fibrous (no main root) usually present Pollen Pollen grain with Pollen grain with one opening three openings Flowers Floral organs usually Floral organs usually in in multiples of three multiples of four or five © 2014 Pearson Education, Inc. 1 Reproductive shoot (flower) Apical bud Node Internode Apical bud Shoot Vegetative shoot system Blade Leaf Petiole Axillary bud Stem Taproot Lateral Root (branch) system roots © 2014 Pearson Education, Inc. 2 © 2014 Pearson Education, Inc. 3 Storage roots Pneumatophores “Strangling” aerial roots © 2014 Pearson Education, Inc. 4 Stolon Rhizome Root Rhizomes Stolons Tubers © 2014 Pearson Education, Inc. 5 Spines Tendrils Storage leaves Stem Reproductive leaves Storage leaves © 2014 Pearson Education, Inc. 6 Dermal tissue Ground tissue Vascular tissue © 2014 Pearson Education, Inc. 7 Parenchyma cells with chloroplasts (in Elodea leaf) 60 µm (LM) © 2014 Pearson Education, Inc. 8 Collenchyma cells (in Helianthus stem) (LM) 5 µm © 2014 Pearson Education, Inc. 9 5 µm Sclereid cells (in pear) (LM) 25 µm Cell wall Fiber cells (cross section from ash tree) (LM) © 2014 Pearson Education, Inc. 10 Vessel Tracheids 100 µm Pits Tracheids and vessels (colorized SEM) Perforation plate Vessel element Vessel elements, with perforated end walls Tracheids © 2014 Pearson Education, Inc. 11 Sieve-tube elements: 3 µm longitudinal view (LM) Sieve plate Sieve-tube element (left) and companion cell: Companion cross section (TEM) cells Sieve-tube elements Plasmodesma Sieve plate 30 µm Nucleus of companion cell 15 µm Sieve-tube elements: longitudinal view Sieve plate with pores (LM) © 2014 Pearson Education, Inc.
    [Show full text]
  • How Long Do Wood Parenchyma Cells Live in the Stem of a Scots Pine (Pinus Sylvestris L.)? Studies on Cell Nuclei Status Along the Radial and Longitudinal Stem Axes
    Article How Long Do Wood Parenchyma Cells Live in the Stem of a Scots Pine (Pinus sylvestris L.)? Studies on Cell Nuclei Status along the Radial and Longitudinal Stem Axes Mirela Tulik 1,* , Joanna Jura-Morawiec 2, Anna Bieniasz 1 and Katarzyna Marciszewska 1 1 Department of Forest Botany, Institute of Forest Sciences, Warsaw University of Life Sciences, 159 Nowoursynowska Str., 02-776 Warsaw, Poland; [email protected] (A.B.); [email protected] (K.M.) 2 Polish Academy of Sciences Botanical Garden—Centre for Biological Diversity Conservation in Powsin, 2 Prawdziwka Str., 02-973 Warsaw, Poland; [email protected] * Correspondence: [email protected]; Tel.: +48-22-593-8032 Received: 9 September 2019; Accepted: 1 November 2019; Published: 4 November 2019 Abstract: This paper deals with the spatial distribution of heartwood in Scots pine stems (Pinus sylvestris L.), determined on the basis of the absence of nuclei in parenchyma cells. Samples were collected at several heights from two Scots pine stems growing in fresh coniferous stand as codominant trees. Transverse and radial sections were cut from the samples and stained with acetocarmine to detect the nuclei and with I2KI to show starch grains. Unstained sections were also observed under ultraviolet (UV) light to reveal cell wall lignification. The shapes of the nuclei in ray and axial parenchyma cells differed: the axial parenchyma cells had rounded nuclei, while the nuclei of the ray parenchyma cells were elongated. The lifespan of the parenchyma cells was found to be 16–42 years; the longest-lived were cells from the base of the stem, and the shortest-lived were from the base of the crown.
    [Show full text]
  • Immunoprofiling of Rice Root Cortex Reveals Two Cortical Subdomains
    METHODS published: 07 January 2016 doi: 10.3389/fpls.2015.01139 Immunoprofiling of Rice Root Cortex Reveals Two Cortical Subdomains Sophia Henry, Fanchon Divol, Mathilde Bettembourg, Charlotte Bureau, Emmanuel Guiderdoni, Christophe Périn * and Anne Diévart * CIRAD, UMR AGAP, Montpellier, France The formation and differentiation of aerenchyma, i.e., air-containing cavities that are critical for flooding tolerance, take place exclusively in the cortex. The understanding of development and differentiation of the cortex is thus an important issue; however, studies on this tissue are limited, partly because of the lack of available molecular tools. We screened a commercially available library of cell wall antibodies to identify markers of cortical tissue in rice roots. Out of the 174 antibodies screened, eight were cortex-specific. Our analysis revealed that two types of cortical tissues are present in rice root seedlings. We named these cell layers “inner” and “outer” based on their location relative to the stele. We then used the antibodies to clarify cell identity in lateral roots. Without these markers, previous studies could not distinguish between the cortex and sclerenchyma in small lateral roots. By immunostaining lateral root sections, we showed that the internal ground tissue in small lateral roots has outer cortical identity. Edited by: Elison B. Blancaflor, Keywords: rice root, cortex, markers, antibodies, lateral roots, tissue identity, confocal microscopy, confocal The Samuel Roberts Noble imaging Foundation, USA Reviewed by: David Domozych, INTRODUCTION Skidmore College, USA Laura Elizabeth Bartley, Rice has a complex root architecture with a mix of embryonic and post-embryonic roots. The University of Oklahoma, USA radicle emerges first during germination, followed soon thereafter by embryonic coronary roots *Correspondence: (Rebouillat et al., 2009; Coudert et al., 2010).
    [Show full text]
  • Histological Investigations of the Secondary Phloem of Gymnosperms
    /\/A/fz#/ ^ *"/ S HISTOLOGICAL INVESTIGATIONS OF THE SECONDARY PHLOEM OF GYMNOSPERMS R. W. DEN OUTER N08201,41 1 WAGENINGEN 582.42/.47:581.824.2 634.0.174.2:634.0.168 HISTOLOGICAL INVESTIGATIONS OF THE SECONDARY PHLOEM OF GYMNOSPERMS PROEFSCHRIFT TER VERKRIJGING VAN DE GRAAD VAN DOCTOR IN DE LANDBOUWKUNDE OP GEZAG VAN DE RECTOR MAGNIFICUS, IR. F. HELLINGA, HOOGLERAAR IN DE CULTUURTECHNIEK, TE VERDEDIGEN TEGEN DE BEDENKINGEN VAN DE SENAAT VAN DE LANDBOUWHOGESCHOOL TE WAGENINGEN OP VRIJDAG 23 JUNI 1967 TE 16.00 UUR DOOR R. W. DEN OUTER H. VEENMAN & ZONEN N.V. - WAGENINGEN - 1967 STELLINGEN I De differentiatie van het vertikale systeem van de bast, loopt parallel met de reductie van de baststralen. Dit proefschrift II De eiwitcellen in debas t van het Chamaecyparispisifera type,vertone n meer overeenkomst metd e begeleidende cellen vand e Angiospermen, dan de eitwitcellen in de bast van hetPseudotsuga taxifolia type. Dit proefschrift III Deter mmergstrale n moet uitsluitend gebruikt worden voor primaire stralen, terwijl secundaire stralen, baststralen genoemd moeten worden, wanneerzi j in het secundaire phloeem voorkomen en houtstralen wanneer zij in het secun­ daire xyleem voorkomen. IV Bij de bast van Gymnospermen is, in tegenstelling met de bast van Angio­ spermen, de mate van aanwezigheid van bastvezels karakteristiek voorhe t ontwikkelingsstadium van het vertikale systeem. ZAHUR, M.S., Cornell Univ. Agr. Exp. St. Mem. 358 (1959) V De opvatting van STRASBURGERda tstippel stusse neiwithoudende -e nzetmeel - houdende systemen zouden ontbreken, isgebleke n onjuist te zijn. STRASBURGER, E., Ober denBa u undde nVerrichtunge n der Leitungsbahnen inde n Pfianzen. Jena (1891) VI De criteria, welke GREGUSS aanlegt bij de rangschikkingvan de houtstralen van de Gymnospermen in verschillende ontwikkelingsstadia, gelden niet voor de baststralen.
    [Show full text]