Endodermal Silicon Deposits and Their Linear Distribution in Developing Roots of Sorghum bicolor (L.) Moench.

Seedlings of Sorghum bicolor (L.) Moench. were cultured in nutrientsolution containing 100 p.p.m. SiO₂. Over periods up to 14 days,the progressive accumulation of Si deposits was recorded bymeans of the electron-probe microanalyser and the scanning electronmicroscope along the seminal root length. An acropetal, linear gradient of Si deposits developed in theendodermis, beginning at the proximal end of the root after1 day, and subsequently extended distally until after 7 days,the total silicified endodermal zone occupied the proximal 75per cent of the root length, a value which remained relativelyconstant thereafter, in spite of root extension. No Si was detectedbelow this zone towards the apex. This result is believed tobe related directly to the asynchronous gradient of cell maturationexhibited by the endodermis behind the apex, and specificallyto the degree of wall development therein. Opaline silica was deposited only in the endodermis, initiallyon the inner tangential wall (ITW) surface after only 1 day,as spherical masses of coalesced, primary particles for whichthe term ‘silica aggregate’ is proposed. A thinlayer of silica over the wall surface was formed as a secondaryphase. The aggregates reached mature size after approximately7 days. Conditions favourable to the inception of silica depositionare discussed including the significance of the chemical compositionof the aggregates, and the importance of the degree of cellulosicthickening, as well as the surface characteristics, of the ITW.     

Pollen Wall Development of Xiphidium coeruleum (Haemodoraceae) and its Systematic Implications

The development of the pollen grain wall in Xiphidium coeruleum(Haemodoraceae) was studied using TEM and cytochemical stainingtechniques. Microsporocyte ontogeny initiates with the degradationof the cellulosic cell wall and subsequent deposition of a thickcallosic cell wall. Following callose deposition, successivemeiosis occurs, resulting in a tetragonal tetrad of microspores.during meiosis, the cell walls of the tapetum break down, releasingthe syncytial periplasmodium. Irregular non-sporopollenous globularbodies are deposited in this peripheral periplasmodium, whichis rich in ER, golgi bodies, vesicles, and characteristic starchplastids. Within the microspore cytoplasm, vesicles, golgi bodies,and plastids are plentiful during the early tetrad stage. Atthis time the plasma membrane of the microspore develops characteristicevaginations. An extracellular membrane, the ‘white line’,is secreted outside the microspore plasma membrane, followedby callose wall degradation. Bead-like deposits of exine orprimexine are deposited at points along the ‘white line’simultaneously on inner and outer surfaces and opposite theoriginal plasma membrane evaginations. The bead-like exine depositscontinue to grow during the release of the microspores and developinto laterally appressed, rod-shaped ektexinous elements havinga tangentially oriented commissure, the vestige of the original‘white line’. The mature intine is two-layered,the outer exintine containing radially oriented vesicular structures,which are apparently derived from plasma membrane extensions.Exine development in Xiphidium is similar to ‘nexine 1’development in Lilium and may have evolved from an ancestraltectate-columellate condition by the loss of the sexine. Walldevelopment in members of the Zingiberales is strikingly similarto that reported here for the Haemodoraceae—evidence ofa possible relationship between the two taxa. Xiphidium coeruleum, Haemodoraceae, pollen, tapetum, development, exine     

Distribution of Silicified Cells in the Leaf Blades of Pleioblastus chino(Franchet et Savatier) Makino (Bambusoideae)

Distribution of silicified cells in the leaf blades of Pleioblastuschino was investigated using a light microscope and a scanningelectron microscope equipped with an energy dispersive X-raymicroanalyser. The most dense accumulation of silica was foundin epidermal tissues. Little silica was deposited in vascularbundles and chlorenchyma, while more was deposited in bundlesheath and fusoid cells. In the epidermis, silica density andfrequency of silicified cells differed depending on cell type,although silica deposition was observed in most cell types.Heavy deposition was found in silica cells, bulliform cells,micro hairs and prickle hairs. Silica cells were the cell typemost frequently silicified (96.9–99.7%) in the adaxialand abaxial epidermis. Silica may be deposited as leaf tissuesage.Copyright 2000 Annals of Botany Company Pleioblastus chino(Franchet et Savatier) Makino, bamboo, silicified cells, leaf blade, epidermis, chlorenchyma, silica, clearing method, freeze-fracturing, freeze-drying, light microscopy, scanning electron microscopy, X-ray microanalysis     

Scanning Electron Microscopy of Silica Deposits in the Culms, Floral Bracts and Awns of Barley (Hordeum sativum Jess.)

Deposits of silica in the culm internodes, floral bracts andawns of Hordeum sativum Jess (cv Deba Abed) have been investigatedusing the scanning electron microscope The deposits were isolatedfrom all organic matter by digestion with nitric and perchloricacids Two basic types of deposits were recognized, lumen andwall silicification, the latter with or without lumen infillings In the culm internodes, lumen deposits are derived from idioblasts(‘hats’), sclerenchyma and xylem vessels In thefloral bracts they are derived from idioblasts (‘hats’and astenform opals), epidermal long cells (dendriform opals),sclerenchyma and xylem vessels The shape of these deposits doesnot generally resemble the outline of the cell itself, but depositsderived from cell walls do closely resemble the infact cell.In the culm, the walls of stomatal cells, trichomes and, largelythe outer tangential walls of mature long epidermal cells, becomesilicified, together with some cork cells In the floral bracts,silica is found in most epidermal cell walls but is confinedto the trichomes, scutiform cells and costal epidermal cellsearly in their development At maturity concentrations of silicaare much higher in the floral bracts and awns than in the culmsand leaves The results are discussed in relation to the pattern of depositionand its possible functions. Hordeum sativum Jess, barley, silica deposits, opals, scanning electron microscopy     

The Ultrastructure and Analytical Microscopy of Silicon Deposits in the Roots of Saccharum officinarum (L.)

Silicon accumulation in the endodermis of the ‘set’and ‘shoot’ roots of Saccharum officinarum (L.)were investigated by scanning electron microscopy and electron-probemicroanalysis. Silicon microassay was also carried out by meansof the Corinth analytical microscope (CORA). Aggregates arelargely associated with the inner tangential wall (ITW) of theendodermis and their formation is basically similar to thoseseen in Sorghum bicolor (L.) Moench. In contrast to Sorghumthe earliest deposits in Saccharum appear in wall strata wellwithin the cell wall cytoplasm interface. An additional layerof silicon was also located along the endodermal pericycle boundaryextending some distance along the middle lamella of the radialwalls. The results are discussed in relation to those of previous studiesof silicon accumulation in endodermal cells and to possiblefactors affecting such accumulations.     

The Polarity of the Cell-wall of Valonia

Further evidence is presented to show that the systems of orientationof cellulose fibrils in the cell-walls of Valonia and Dictyosphaeriamay be described by reference to two ‘poles’ uponwhich these orientation systems converge. The ‘poles’are real structural features of the wall.     

Function of silica bodies in the epidermal system of rice (Oryza sativa L.): testing the window hypothesis

Silicon has been considered to be important for normal growthand development of the rice plant (Oryza sativa L.). To investigatethe physiological function of deposited silica in rice leaves,the hypothesis that silica bodies in the leaf epidermal systemmight act as a ‘window’ to facilitate the transmissionof light to photosynthetic mesophyll tissue was tested. Thesilica content of leaves increased with supplied silicon andwas closely correlated with the number of silica bodies perunit leaf area in the epidermal system. There was a significantdifference in silica deposition and formation of silica bodiesbetween Si-treated and non-treated leaves; silicon was polymerizedinside the silica cells and bulliform cells of the epidermis,in Si-treated leaves. Although the ‘windows’ wereonly formed in leaves with applied silicon, optical propertiesof leaf transmittance, reflectance and absorptance spectra inSi-treated and non-treated leaves were almost equal. Furthermore,light energy use efficiency and quantum yield of Si-treatedleaves were less than in leaves not containing silica bodies.Thus, silica bodies, at least based on the data, do not functionas windows in rice leaves. Key words: Silicon, window hypothesis, rice, optical property, quantum yield     

Structure and Function of Silica Bodies in the Epidermal System of Grass Shoots

Silica (SiO₂.nH₂O) is deposited in large quantities in the shootsystems of grasses. In the leaf epidermal system, it is incorporatedinto the cell wall matrix, primarily of outer epidermal walls,and within the lumena of some types of epidermal cells. This biogenic silica can be stained specifically with methylred, crystal violet lactone, and silver amine chromate. At theultrastructural level, the silica in lumens of silica cells,bulliform cells and long epidermal cells is made up of rodsabout 2.5 µm in length and 0.4µm in width. Ultimateparticles in the rods range from 1 to 2 nm in diameter. In contrast,silica in the cell wall matrix of trichomes and outer wallsof long epidermal cells is not rod-shaped, but rather, formsroughly spherical masses. Detailed analyses are presented on the frequencies of occurrenceof the different types of epidermal cells that contain silicain the leaves of representative C₃ and C₄ grasses. The C₄ grasseshave higher frequencies of bulliform cell clusters, silica cells,and long epidermal cells, whereas the C₃ grasses have higherfrequencies of trichomes. No correlation was found in the frequencyof occurrence of silica bodies in bulliform cells for C₃ grassesas compared with C₄ grasses. Of all the grasses examined, Coix,Oryza, and Eleusine had the highest densities of such bodies,and some taxa had no silica bodies apparent in their bulliformcells. The idea that silica bodies in bulliform cells and silica cellsmight act as "windows’ and trichomes might function as‘light pipes’ to facilitate light transmission throughthe epidermal system to photosynthetic mesophyll tissue belowwas tested. The experimental data presented do not support eitherof these hypotheses. C₂ and C₄ grasses, biogenic silica, light pipes, window hypothesis, silica staining, silica ultrastructure     

Leaf Anatomy, Emphasizing Unusual 'Concertina' Mesophyll Cells, of Two East African Legumes (Caesalpinieae, Caesalpinioideae, Leguminosae)

Cordeauxia edulis (Somalia and Ethiopia), andStuhlmannia moavii(Tanzania, Kenya and Madagascar) are evergreen shrubs or smalltrees of dry areas. They have similar leaf anatomy as revealedby resin sectioning and scanning electron microscopy. The cuticleis extremely thick and all vascular bundles lack bundle sheathextensions. The most unusual feature is the mesophyll, threeto seven layers consisting entirely of cylindrical palisadecells with lateral walls capable of changing vertical lengthby folding in a concertina-like manner. The matching outwardfolds of two adjacent cells always remain attached by meansof a row of wall thickenings (‘pegs’). The pegscan elongate, especially so between the widely separated mesophyllcells that occupy the substomatal chamber area. The unattachedflexible inward wall folds enable these ‘concertina’cells to shorten or lengthen vertically without disrupting cellinterconnections in the interior of each relatively long-livedleaf as it periodically loses and gains water. Concertina cellsmay be an anatomical adaptation allowing these leaves to remainevergreen and survive extended periods of drought and yet tostore water quickly when it becomes available. Leguminosae; Caesalpinioideae; Cordeauxia ; Stuhlmannia ; ‘concertina’ mesophyll cells; desert adaptation; hollow glandular trichomes; leaf anatomy; wall thickenings     

Studies on Mature Seeds of Cuscuta pedicellata and C. campestris by Electron Microscopy

The seeds of Cuscuta pedicellata have been investigated by transmissionand scanning electron microscopy. Additional observations havebeen made on seeds of C. campestris by SEM only. The seed coatconsists of an outer single epidermis, two different palisadelayers, and an inner multiparenchyma layer. The outer epidermalwall in C. pedicellata has a thick cuticle and zones rich inpectic substances. The thicker ‘U-shaped’ cell wallsin the outer palisade layer are strengthened by a wall layerof hemicellulose. The inner palisade layer has thick walledcells with a ‘light line’. The inner cell wall ofthe compressed multiparenchyma layer has a thin cuticle. A fairlythick cuticle is positioned directly on the endosperm surface.The aleurone cell walls are different from the remaining endospermwalls. The latter are thick and believed to be of galactomannans.There is a ‘clear’ zone between the plasmalemmaand the cell wall in the aleurone cells. The embryo cells arepacked with lipids and proteins. In Cuscuta campestris mostendosperm has been absorbed during the seed development. Theembryo apex has two minute leaf primordia. The features of theCuscuta seeds are discussed in relation to functional and environmentalconditions. Cuscuta pedicellata, Cuscuta campestris, seed, seed coat, cuticle, cell walls, endosperm, aleurone cells, galactomannan, embryo, TEM, SEM     

Immunological Identification of a Putative Precursor of the Insoluble Glycoprotein Framework of the Chlamydomonas Cell Wall

To identify precursors of the insoluble glycoprotein frameworkof the Chlamydomonas cell wall, a polyclonal antibody was raisedagainst the mixture of polypeptides released from the insolublewall fraction by chemical deglycosylation. This antibody preferentiallycross-reacted with a ‘150 kDa’ salt-soluble cellwall glycoprotein. The conclusion that this ‘150 kDa’glycoprotein is a putative precursor of the insoluble cell wallfraction was corroborated by the results of pulse-chase experimentsand by experiments with antibodies raised against the ‘150kDa’ salt-soluble glycoprotein and against its 100 kDadeglycosylation product, respectively. Whereas the antibodyagainst the ‘150 kDa’ glycoprotein preferentiallyrecognized carbohydrate side chains, the antibody against its100 kDa deglycosylation product was found to have essentiallythe same specificity towards glycosylated and deglycosylatedcell wall components as the antibody against the deglycosylationproducts of the insoluble wall fraction. Furthermore, the antibodyagainst the deglycosylated, insoluble wall fraction recognizedalmost the same set of peptide fragments derived by V8 proteasetreatment from the ‘150 kDa’ salt-soluble cell wallglycoprotein and its 100 kDa deglycosylation product, respectively,as the antibody against the 100 kDa deglycosylated cell wallpolypeptide. (Received April 22, 1994; Accepted November 21, 1995)     

The Developmental Anatomy of the Root System in Yam Bean, Pachyrhizus erosus Urban

Investigations revealed that the anatomy of the primary radicularroot of yam bean (Pachyrhizus erosus L.) was typically dicotyledonousexcept that the xylem was not completely developed centripetally.Most of the roots had tetrarch xylem, although a few triarchand pentarch roots were also observed. In both tuberous andnon-tuberous roots, secondary thickening occurred by the formationof the meristematic vascular cambium which formed secondarytissues in a normal fashion. Subsequently, tuberization wasinitiated in the secondary xylem by the development of anomalous‘secondary’ cambia from parenchyma cells surroundingvessel elements. Anomalous ‘secondary’ cambia alsodeveloped from parenchyma cells not associated with vessels.Subsequently, anomalous ‘tertiary’ cambia differentiatedfrom tissues produced by the anomalous ‘secondary’cambia. Activities of these anomalous cambia resulted in theproduction of parenchyma storage cells and were chiefly responsiblefor the growth of the mature tuber. Pachyrhizus erosus L., yam bean, tuberous root, anatomy, anomalous ‘secondary’ cambia, anomalous ‘tertiary’ cambia, centripetal xylem development     

Developmental Genetics and Morphological Evolution of Flowering Plants, Especially Bladderworts (Utricularia): Fuzzy Arberian Morphology Complements Classical Morphology

This review compares new developmental models on flowering andother vascular plants with evolutionary hypotheses formulatedby Agnes Arber (1879–1960) and like-minded botanists.Special emphasis is laid on philosophical basics such as perspectivism,pluralism about evolutionary modelling, continuum way of thinking,and fuzzy logic. Arber's perspective is best labelled as F uzzyA rberian M orphology (FAM Approach). Its proponents (‘FAMmers’)treat structural categories (e.g. ‘roots’, ‘shoots’,‘stems’, ‘leaves’, ‘stipules’)in vascular plants as concepts with fuzzy borderlines allowingintermediates (including transitional forms, developmental mosaics).The FAM Approach complements Cla ssical Plant M orphology (ClaMApproach), which is the traditional approach in botany. ClaMproponents (‘ClaMmers’) postulate that the structuralcategories of vascular plants are regarded as concepts withclear-cut borderlines and without intermediates. However, duringthe evolution of vascular plants, the root-shoot distinctionand the stem-leaf distinction have become blurred several timesdue to developmental changes, resulting in organs with uniquecombinations of features. This happened, for example, in thebladderworts (Utricularia, Lentibulariaceae). When focusingon the ‘leaf’, the FAM Approach is identical toArber's ‘partial-shoot theory of the leaf’ and Sinha's‘leaf shoot continuum model’. A compound leaf canrepeat the developmental pathway of the whole shoot, at leastto some degree. For example, compound leaves of Chisocheton(Meliaceae)with indeterminate apical growth and three-dimensional branchingmay be seen as developmental mosaics sharing some growth processeswith whole shoots! We focus here on the FAM Approach becausethis perspective is especially promising for developmental geneticistsstudying flowering and other vascular plants. Copyright 2001Annals of Botany Company Review, body plan, developmental mosaics, leaf development, history of botany, homeosis, homeotic genes, Lentibulariaceae, morphological evolution, process morphology, stipules, Utricularia, flowering plants     

The growing outer epidermal wall: design and physiological role of a composite structure

Background: The cells of growing plant organs secrete an extracellular fibrouscomposite (the primary wall) that allows the turgid protoplaststo expand irreversibly via wall-yielding events, which are regulatedby processes within the cytoplasm. The role of the epidermisin the control of stem elongation is described with specialreference to the outer epidermal wall (OEW), which forms a ‘tensileskin’. Novel Facts: The OEW is much thicker and less extensible than the walls ofthe inner tissues. Moreover, in the OEW the amount of celluloseper unit wall mass is considerably greater than in the innertissues. Ultrastructural studies have shown that the expandingOEW is composed of a highly ordered internal and a diffuse outerhalf, with helicoidally organized cellulose microfibrils inthe inner (load-bearing) region of this tension-stressed organwall. The structural and mechanical backbone of the wall consistsof helicoids, i.e. layers of parallel, inextensible cellulosemicrofibrils. These ‘plywood laminates’ containcrystalline ‘cables’ orientated in all directionswith respect to the axis of elongation (isotropic material).Cessation of cell elongation is accompanied by a loss of order,i.e. the OEW is a dynamic structure. Helicoidally arranged extracellularpolymers have also been found in certain bacteria, algae, fungiand animals. In the insect cuticle crystalline cutin nanofibrilsform characteristic ‘OEW-like’ herringbone patterns. Conclusions: Theoretical considerations, in vitro studies and computer simulationssuggest that extracellular biological helicoids form by directedself-assembly of the crystalline biopolymers. This spontaneousgeneration of complex design ‘without an intelligent designer’evolved independently in the protective ‘skin’ ofplants, animals and many other organisms.     

Factors Affecting the Abscission of Reproductive Organs in Yellow Lupins (Lupinus luteus L.): III. ENDOGENOUS GROWTH SUBSTANCES IN VIRUS-INFECTED AND HEALTHY PLANTS AND THEIR EFFECT ON ABSCISSION

Extracts of small and mature-size lupin pods yielded four substancesaffecting the growth of wheat-coleoptile sections: one acidpromotor (A), two acid inhibitors(B and X), and one neutralinhibitor(Y). Inhibitor B was extremely active, however, coleoptile sectionsshowed no signs of toxic effects; they resumed growth at a rapidrate after rinsing them and adding ß-indolylaceticand (IAA) to the medium. 1 µg of IAA was required to counteractthe effect of ‘B’ extracted from 230 mg. Of tissue.On an equal fresh weight basis the inhibiting action of ‘B’in lupin pods was 500–1,500 times more potent than thatof ‘inhibitor ß’ in etiolated pea seedlings. Small pods of plants infected with pea-mosaic virus yielded3 times the amount of ‘A’ of healthy plants (equivalentto 1 µg. IAA 0.3 µg. IAA per 25 g. of tissue respectively),and approximately the amount of ‘B’. Mature podsof virus-infected plants again yielded more‘A’,but also 2? times more ‘B’ than pods of healthyplants. Healthy pods yielded more ‘A’ than virus-infectedpods, and there was no difference in ‘X’. A lupin abscission test was developed and the effects of proximaland distal application of -naphthyl acetic acid (NAA) are presented,and discussed with respect to results of other abscission tests. ‘A’ accelerated abscission when applied proximally,and delayed or prevented it when applied distally. ‘B’strongly accelerated abscission when applied in either way.A possible mechanism explaining the abscission-inducing effectof developing pods on later flowers is discussed in terms ofthe substances ‘A’ and ‘B’. The partlyprevented abscission observed on virus-infected plants was foundto agree well with the proposed mechanism.     

The Nitrogen Content of Plants and the Self-thinning Rule of Plant Ecology: A Test of the Core-skin Hypothesis

The ‘core-skin’ hypothesis postulates that secondarilythickened plants behave energetically as an inert ‘core’covered by an active ‘skin’, the ‘skin’being two-imensional, the ‘core’ three-dimensional.This would explain the ‘self-thinning ‘or‘–3/2’ rule of plant ecology, that is, the tendencyfor log (dry weight per plant) and log (number of plants perunit area) to progress along a straight line relationship, withslope = – 3/2’. The hypothesis was tested as follows. Plant nitrogen contentwas used as an estimate of the mass of ‘skin’ perplant, and dry weight as an estimate of the mass of the ‘core’.As plants mature the slope of the relationship between y = log(mass of nitrogen per plant) and x = log (mass of dry matterper plant) is expected to decline from an initial value of 1.0towards a final value of 0.66. The intercept of the relationshipis expected to reflect the intrinsic content of ‘skin’per unit of ‘core’. Genotypic variation in thisparameter should cause genotypic differences in the maximumattainable yield of biomass per unit area. The expectations were investigated by fitting the function y= p+qx+r exp – x to 30 sets of data on plant nitrogencontent, plant weight and time in 18 different vegetables. Simplelinear regressions of y on x were fitted to more limited setsof data on weights and nitrogen contents of mature trees. Theexpectations were, with some minor exceptions, confirmed. Nitrogen, yield, plant competition, self-thinning     

Dimorphism and Monomorphism in the Plumbaginaceae: II. Pollen and Stigmata In the Genus Limonium

A survey of pollen- and stigma-dimorphism and monomorphism inthe genus Limonium (as understood at present) reveals considerableheterogeneity which is useful for the solution of taxonomic,phylogenetic, and phytogeographic problems. Two main pollen types (A and B) and two main stigma types (coband papillate) occur in the genus. Capitate stigmata also occur. ‘Type A’ pollen has frequently been found in conjunctionwith ‘papillate’ stigmata as a secondarily monomorphic(self-compatible) combination and this must have arisen at leastfour times in the genus as well as in Armeria. ‘Type B’pollen and ‘cob’ stigmata are recorded togetherfor the first time (also as a secondarily monomorphic, self-compatiblecombination) in L. echioides. Apomixis, already discovered insubsections Densiflorae and Dissitiflorae, has been found inL. cosyrense of the subsection Steirocladae. The taxonomic and phylogenetic significance of the facts indiscussed.     

Effects of Inorganic Phosphate on the Utilization of Sucrose by Suspension-cultured Catharanthus roseus Cells

The metabolic fate of [U-¹⁴C]sucrose in suspension culturesof Catharanthus roseus cells was monitored for 96 h after thecells were transferred to fresh complete (‘+Pi’)or to phosphate-deficient Murashige and Skoog (‘–Pi’)medium. Sucrose was hydrolysed extracellularly to glucose andfructose. The rate of uptake of sugars by the cells was 1.5–3times higher in ‘+Pi’ culture than in ‘–Pi’culture. Little difference in the rate of incorporation of radioactivityinto the ethanol-soluble fraction was found between the ‘+Pi’and ‘– Pi’ cultures during the initial 24h of culture, but after 48 h the rate in ‘ +Pi’cultures was higher than that in ‘–Pi’ cultures.Incorporation of radioactivity into ethanol-insoluble macromoleculeswas always significantly higher in the cells in ‘+Pi’cultures than in those in ‘–Pi’ cultures.The results suggest that Pi strongly affects the utilizationof sugars by cultured plant cells through the stimulation oftransport of sugars as well as through the activation of metabolism. Catharanthus roseus, Madagascar periwinkle, suspension culture, inorganic phosphate, sucrose, transport, metabolism     

Structural and Histochemical Changes in Palisade Cells of Prosopis juliflora Seed Coat in Relation to its Water Permeability

Histochemical investigations on the Prosopis juliflora seedcoat indicate the occurrence of a hydrophobic ‘strip’as the primary water barrier. Its position and the structureand histochemistry of the palisade cells of the seed coat differaccording to their location on the seed. These differences maybe responsible for differences in the water permeability ofvarious parts of the seed coat. In particular, parts of theseed coat in which the hydrophobic ‘strip’ is locatedmore superficially tend to be more water impermeable than partslike the chalaza, in which the ‘strip’ is more deeplylocated within the palisade cells. Prosopis juliflora, seed coat impermeability, palisade cells, hydrophobic ‘strip’     

CORRECTIONS, VOLUME 29

Part 1, under the frontispiece portrait of Dr. N. B. Eales,the words ‘President 1948–1951’ should havebeen added. Page 103, line 49, for ‘Newton Collection’ read‘Norman Collection (Canon Norman)’. 185, line 37, for ‘capillaris’ read ‘capillacca’. 188, Table 1, for ‘bemoralis’. read ‘nemoralis’. 188, Table 2, for ‘Cochlicella acuta (Müll)? ventrosa(Fér.)’ read ‘Cochlicella ventrosa (Fér.)’. 191, line 24, for ‘araheo-’ read ‘archeo-’.