Abscisic Acid and the Regulation of Water Loss in Plantlets of Brassica oleracea L. var. botrytisRegenerated Through Apical Meristem Culture

Water loss was studied in regenerated plantlets of Brassicaoleracea var. botrytis cv. Currawong derived through apicalmeristem culture. Hardening of plantlets was eliminated by asingle application of a polyvinyl resin (S600) sprayed immediatelyafter transplanting. Plantlets sprayed with S600 had highercuticular resistances than unsprayed plantlets; this treatmenthad no effect on stomatal resistance. Leaves formed during theculture period showed very little wax formation and using markedleaves it was found that only reduced levels of wax formed onthese leaves even after transplanting. New leaves formed aftertransplanting, showed typical wax formation compared to seedgrown plants. Abscisic acid (ABA) at 10^–4 M applied as a leaf sprayto transplants did not cause a substantial increase in stomatalresistance in leaves which had been initiated during the cultureperiod. Leaves of seed-grown plants as well as leaves of plantletsformed after transplanting did respond to a leaf spray of ABAat 10^–4 M by a large increase in stomatal resistance. Relative concentrations of K, Na, Ca, P, S and Mg in guard cellswere calculated for each leaf type by X-ray micro-probe analysis.K/Na values decreased in the order: seedling > leaves formedafter transplanting > leaves intiated during culture. A highpositive correlation was also found between K/Na and K/P forthe three leaf types. K:Mg and K:Ca ratios for leaves formedduring culture were low in comparison to the values obtainedfor leaves formed after transplanting and seedlings for whichthe values were similar. Brassica oleracea var. botrytis, cauliflower, regenerated plantlets, meristem culture, stomatal resistance, water loss, abscisic acid, X-ray micro-probe analysis     

Cuticular permeability of the three tree species Prunus Iaurocerasus L., Ginkgo biloba L. and Juglans regia L.: comparative investigation of the transport properties of intact leaves, isolated cuticles and reconstituted cuticular waxes

Cuticular transport properties of intact leaves, isolated cuticularmembranes and reconstituted cuticular waxes of the three treespecies Prunus laurocerasus L., Ginkgo biloba L. and Juglansregia L. were measured using six different ¹⁴C-labelled compounds,benzoic acid, salicylic acid, 2,4-dichlorophenoxy acid, metribuzin,4-nitrophenol, and atrazine. For the same compound and the samespecies, the permeance of the intact leaf and the isolated cuticlewas equal. This provides strong evidence demonstrating thattransport properties of cuticles are not altered during isolation.Additionally, diffusion coefficients of the ¹⁴C-labelled compoundsin isolated and subsequently reconstituted cuticular wax ofthe three tree species were measured. Permeances of intact leavesand isolated cuticles could be predicted from diffusion coefficients,wax/water partition coefficients and the thickness of the transport-limitingwax layer with a mean deviation of about 1.7. This providesevidence that transport properties of recrystallized cuticularwaxes do indeed reflect barrier properties of isolated cuticularmembranes and intact leaves with in situ waxes. Thus, it canbe concluded that the investigation of cuticular permeabilityusing the three independent experimental systems of differentcomplexity give comparable results. Finally, it was observedthat permeances and diffusion coefficients measured with P.laurocerasus were always significantly lower than those measuredwith G. biloba and J. regia. This is interpreted as an ecologicaladaptation of the respective species. The evergreen speciesP. laurocerasus must be more adapted to environmental stresssuch as drought and frost injury compared to the two deciduousspecies G. biloba and J. regia. Key words: Cuticular permeability, diffusion coefficient, leaf surface, permeance, plant cuticle, transport     

Epicuticular Wax Columns in CultivatedBrassicaSpecies and in their Close Wild Relatives

Three different types of epicuticular wax columns were foundinBrassicaspecies with a chromosome number (n)=9: long columns(LC), short columns (SC) and netted columns (NC). LC were foundinB. incanaandB. rupestris.SC were found inB. villosa, B. macrocarpa,B. cretica, B. hilarionisand also inB. montana. B. insulariscolumnswere intermediate. NC waxes were found inB. oleraceaand itsclose alliesB. alboglabraandB. bourgeaui.Samples ofB. rapa (n=10)andB.nigra (n=8)examined did not show any wax columns but their amphidiploidswithB. oleracea (B. napusandB. carinata,respectively) seemedto inherit the NC type of wax present inB. oleracea.Copyright1999 Annals of Botany Company Brassica, waxes, wax columns, leaf surface.     

Morphological, Physical and Chemical Characteristics of Epicuticular Wax on Ornamental Plants Regenerated In Vitro

The morphological and physical characteristics of epicuticularwax of Maranta, Dieffenbachia, Chrysanthemum, Spathiphyllum,and Gerbera grown in a greenhouse, growth chamber, or in vitro,were determined by scanning electron microscopy (SEM) and gravimetricanalysis. Morphological characteristics varied among the differentspecies ranging from ridges in Dieffenbachia to smooth surfacesin Chrysanthemum and Gerbera. There was no consistent appearanceof wax of plants grown in vitro. Gravimetric analysis was necessaryto determine the amounts of wax accurately. Thin-layer chromatographyand gas-liquid chromatography revealed chemical differencesin the wax from different treatments within each species. Therewas no correlation between survival in the greenhouse or amountof leaf damage and the amounts of epicuticular wax present onplants at time of transfer. A comparison of results from gravimetricanalysis and SEM indicated that SEM alone cannot be used withconfidence in determining either the presence or the relativeamounts of epicuticular wax present. In addition, morphologicaldifferences in epicuticular wax of greenhouse, growth chamber,and cultured plants cannot be predicted from the growth environmentof plants and must be determined individually for each speciesunder study. Dieffenbachia maculata, Maranta leuconeura, Chrysanthemum morifolium, Gerbera jamesonii, Spathiphyllum wallissii, micropropagation, epicuticular wax     

Seasonal Changes of Bioelements in the Litter and their Potential Return to Green Leaves in four Species of the Argentine Subtropical Forest

The aim of this work was to analyse the nutrient concentrationsof N, P, Ca, Mg, K and Na in mature leaves, branches and fruitsand to investigate relationships between the contents of thesebioelements in senescent and fresh leaves in four forest species:Gleditsia amorphoides ( Espina Corona), Patagonula americana(Guayaibí),Chlorophora tinctoria ( Mora) and Astroniumbalansae (Urunday). The study site was located in the ColoniaBenítez Estricta Nature Research (Chaco, Argentina).In this subtropical forest, total litter was collected monthlyand was sorted into three groups: (1) leaves; (2) branches andfruit; (3) unidentified. Total dry matter was recorded and analysedfor N, P, Ca, Mg, K and Na. Espina Corona had the highest leafconcentrations of N, while Mora had the highest concentrationsof Ca and Mg. The highest leaf concentrations of P were foundin Espina Corona, Mora and Urunday. No significant differencesin K were found among the different species. Na concentrationswere higher in Espina Corona and Guayaibí than Mora andUrunday. A marked seasonal variability was observed in the concentrationsof N, P and K, with no important differences for Ca and Mg,except in Espina Corona. These variations in nutrient concentrationswere greater in leaves than in branches and fruits. N and Pwere translocated to other tree organs and Ca, Mg and Na wereaccumulated in mature leaves. The bioelement K is the only onethat undergoes leaching and mobilization in all species. ResorbedN and P can be used for the production of new leaf organs inthe following annual cycle. This resorption supports a portionof the production of new foliage, diminishing the demand fromsoil.Copyright 2000 Annals of Botany Company Above-ground production, potential return, nutrient resorption, leaf analysis, tropical forest, Gleditsia amorphoides, Patagonula americana, Chlorophora tinctoria, Astronium balansae, Espina Corona, Guayaibí, Mora, Urunday.     

Comparative Leaf Surface Morphology and the Glossy Characteristic of Sorghum, Maize, and Pearl Millet

Leaf surfaces of seven genotypes of Sorghum bicolor, two ofmaize, Zea mays, and two pearl millet, Pennisetum americanum,were examined by scanning electron microscopy for possible morphologicaldifferences. Leaves 1, 3, 5 and 7 were photographed and printswere used to estimate waxiness, hairiness or pubescence andstomatal density. Glossiness was determined by spraying water,which adhered to the glossy leaves. Cuticular transpirationof detached third and fifth leaves was estimated from the rateof water loss after abscisic acid induced stomatal closure.Sorghum lines SC283, CSM63, CSM90, and pearl millets Souna andTiotioni (all from Mali), were non-glossy, well covered withwax, and exhibited variable hairiness. Older leaves of sorghumvarieties Martin and Redlan were glossy and, like older leavesof the other glossy lines SC1096 and SC90, had little or nowax deposits on their cuticles. The two maize cultivars, NB611and N7A, were non-glossy with dense wax covering; no trichomeswere observed until the 5 to 7 leaf stage. Thus, the glossycharacter was correlated with the reduction or absence of waxdeposits on the leaf surfaces, while hairiness might occur ineither glossy or non-glossy genotypes. Unlike sorghum and maize,in which all leaves after the fifth or seventh were glossy,pearl millet showed no glossiness through the ninth leaf. Measurementsshowed that cuticular transpiration of glossy leaves was oftenmore than double that of non-glossy leaves. Comparisons amongsorghums showed that non-glossy lines had higher stomatal densitiesthan glossy lines. Epicuticular wax, trichome, glossy mutant, stomata, cuticular transpiration, Sorghum bicolor, (L.) Moench, Zea mays L., Pennisetum americanum, (L.) Leeke     

Sclerophylly and Plant Water Relations in Three Mediterranean Quercus Species

The possible role in drought resistance played by sclerophyllywas studied in the Mediterranean oaks Quercus ilex, Q. suberand Q. pubescens. Studies were conducted on leaves at 30, 50and 80% of their final surface area, as well as on mature leavesof the current year's growth in June and September and on 1-year-oldleaves. Leaves of different ages of the three species showed quite differentdegrees of sclerophylly (DS). Q. ilex leaves reached the definitiveDS of 1.75 g dm^–2 during leaf expansion; Q. pubescensleaves hardened at the end of their expansion, with a finalDS of 0.93 g dm^–2; Q. suber showed the lowest DS of 0.76g dm^–2. Leaf conductance to water vapour (g₁) of 1-year-old leaves ofQ. ilex, measured in the field, showed a duration of the g₁peak values about twice that of the other two species. The minimumleaf relative water content (RWC), however, was near the samein the three species, indicating that water loss was recoveredpartly by Q. ilex leaves. This was apparently due to the higherbulk modulus of elasticity (     

Phloem Mobility of Boron is Species Dependent: Evidence for Phloem Mobility in Sorbitol-rich Species

Boron is generally considered to be phloem immobile or to haveonly limited phloem mobility in higher plants. Evidence suggests,however, that B may be mobile in some species within thePyrus,Malus andPrunusgenera. These genera utilize sorbitol as a primarytranslocated photosynthate and it has been clearly demonstratedthat B forms stable complexes with sorbitolin vitro.In the researchpresented here we demonstrate, further, that B is freely phloemmobile inPyrus, MalusandPrunusspecies and suggest that thisis mediated by the formation and transport of B-sorbitol complexes. The pattern of B distribution within shoot organs and the translocationof foliar-applied, isotopically-enriched¹⁰B was studied in sixtree species. Results demonstrate that in species in which sorbitolis a major sugar (sorbitol-rich), B is freely mobile while inspecies that produce little or no sorbitol (sorbitol-poor) Bis largely immobile. The sorbitol-rich species used here werealmond [Prunus amygdalusB. syn.P. dulcis(Mill.)], apple (MalusdomesticaB.) and nectarine (Prunus persicaL. B. var.nectarinaM.),sorbitol-poor species included fig (Ficus caricaL.), pistachio(Pistacia veraL.) and walnut (Juglans regiaL.). In sorbitol-richspecies foliar applied¹⁰B was transported from the treated leavesto adjacent fruit and specifically to the fruit tissues (hull,shell or kernel) that developed during the experimental period.Whereas, foliar-applied¹⁰B was rapidly translocated out of leaves,only a small percentage of the¹¹B present in the leaf at thetime of foliar application was retranslocated. In sorbitol-richspecies, B concentrations differed only slightly between oldand young leaves while fruit tissue had significantly greaterB concentrations than leaves. In contrast, sorbitol-poor specieshad significantly higher B concentrations in older leaves thanyoung leaves while fruit tissue had the lowest B concentration.This occurred irrespective the source of plant B (soil, solutionor foliar-applied). In a subsequent experiment the growth ofapple trees in solutions free of applied B was maintained solelyby foliar applications of B to mature leaves. These resultsindicate that B is mobile in species that produce significantamounts of sorbitol. We propose that the mobility of B in thesespecies is mediated by the formation of B-sorbitol complexes. Almond; Prunus amygdalus ; apple; Malus domestica; nectarine; Prunus persica; fig; Ficus carica; pistachio; Pistacia vera; walnut; Juglans regia; boron; phloem mobility; deficiency; toxicity; inductively coupled plasma-mass; spectrometer     

Effectiveness of short‐tongued bees as pollinators of apparently ornithophilous New Zealand mistletoes

Abstract The flowers of two species of threatened New Zealand mistletoes (Peraxilla tetrapetala and Peraxilla colensoi, Loranthaceae) have explosive buds that do not open unless force is applied by birds or two species of native short‐tongued bees. Opened flowers are visited by a variety of birds and insects. Although both species of Peraxilla conform to a pollination syndrome of ornithophily, bees may be effective alternative pollinators. We investigated the effectiveness of bees and birds as pollinators of P. colensoi at one site and P. tetrapetala at two sites in the South Island. Bees and other insects outnumbered birds as flower visitors at all three sites. By excluding birds with wire cages, we showed that two bee species regularly open flowers of P. tetrapetala, but only rarely open flowers of P. colensoi. Few pollen grains were deposited when either birds or bees opened buds, so opening buds was not by itself sufficient for adequate pollination. Instead, pollen continued to accumulate over the next 6 or 7 days, even inside cages that excluded birds. Both populations of P. tetrapetala were regularly pollen‐limited, but in different ways. At Ohau, opened flowers gained enough pollen to produce seeds, but many buds were not opened and hence failed to set seed. In contrast, at Craigieburn, nearly all buds were opened, but many of these did not receive enough pollen. These results demonstrate that native bees can partially replace birds as pollinators of mistletoes, despite their apparent ornithophilous syndrome. Ongoing reductions in New Zealand forest bird numbers means that the service bees provide may be important for the long‐term future of these plants.     

Seasonal Dimorphism in the Mediterranean Cistus incanus L. subsp. incanus

Mediterranean perennial species are described as being sclerophyllous,or summer deciduous, or seasonally dimorphic. Field observationin the coastal maquis of Castelvolturno Nature Reserve, southernItaly, showed thatCistus incanus L. subsp. incanus is a seasonallydimorphic species as it develops brachyblasts with small leavesin summer, and dolichoblasts with large leaves in winter. Fieldbiometric data confirmed that winter shoots were 14-times longerthan those developed in summer and had many more leaves. Thearea of single winter leaves was five-times that of summer leaves.Anatomical leaf structure also changed with the season: winterleaves were flat while summer leaves had a crimped lamina whichwas partially rolled to form crypts in the lower surface. Leaveswere covered by considerably more trichomes in summer than inwinter. Stomata were uniformly distributed along the lower epidermisof winter leaves but were only present in the crypts of summerleaves. In summer leaves, a palisade layer was often found onboth sides of the lamina, the mesophyll cells were generallysmaller and the intercellular spaces were reduced. Winter leaveshad a dorsiventral structure and larger intercellular spaces.Seasonal dimorphism is generally reported to be an adaptationto summer drought. However, the morphology and anatomy of C.incanus L. subsp.incanus showed that the subspecies has notonly developed a strategy to survive summer drought, but hasevolved two different habits, one more xerophytic than the other,to optimize adaptation to the seasonal climatic changes occurringin Mediterranean environments. Copyright 2001 Annals of BotanyCompany Cistus, Cistus incanus L. subsp. incanus, climatic changes, leaf anatomy, leaf dimorphism, Mediterranean shrubs, phenology, seasonal dimorphism     

Limnocalanus macrurus (Copepoda: Calanoida) retains a marine arctic lipid and life cycle strategy in Lake Michigan

Limnocalanus macrurus, an omnivorous calanoid copepod with strongcarnivorous tendencies that invaded fresh water during the Pleistoceneglaciation, retains a marine arctic lipid and life cycle strategyin the hypolimnion of Lake Michigan. Its maximum lipid concentrationof 67% of dry mass—consisting largely of wax esters—isthe highest reported for freshwater zooplankton and is amongthe highest reported for marine polar species. The high lipidconcentration of L.macrurus runs counter to the paradigm thathigh wax ester concentrations are found in herbivorous, butnot in carnivorous, polar species. Lipids are drawn down toextremely low levels (10% of dry mass) during the reproductiveperiod, November–May. Reproduction in this univoltinespecies appears to be timed so that the new generation developsduring the high abundance of prey (crustacean microzooplanktonand net phytoplankton) in spring. A high wax ester content mayallow egg production to start in winter when the prey concentrationis low. In contrast to many polar species, the new generationmoves through all copepodid stages to adult without diapausing.Copepodid 5 females have a low lipid concentration, and lipidsare slowly built up in new generation adults during summer andfail before reproduction commences. This lipid and life cyclestrategy may have given L.macrurus an advantage over potentialfreshwater competitors, such as the arctic freshwater cyclopoidcopepod Cyclops scutifer, in the hypolimnia of glaciated lakes.     

Distribution of enzymes related to C3 and C4 pathway of photosynthesis between mesophyll and bundle sheath cells of Panicum hians and Panicum milioides

Enzymes of the C₄, C₃ pathway and photorespiration have beenanalyzed for P. hians and P. milioides, which have chlorenchymatousbundle sheath cells in the leaves. On whole leaf extracts thelevels of PEP carboxylase are relatively low compared to C₄species, RuDP carboxylase is typical of C₃ species, and enzymesof photorespiratory metabolism appear somewhat intermediatebetween C₃ and C₄. Substantial levels of PEP carboxylase, RuDPcarboxylase, and photorespiratory enzymes were found in bothmesophyll and bundle sheath cells. Low levels of C₄-acid decarboxylatingenzymes may limit the capacity for C₄ photosynthesis in P. hiansand P. milioides. The results on enzyme activity and distributionbetween mesophyll and bundle sheath cells are consistent withCO₂ fixation via C₃ pathway in these two species. ¹ This research was supported by the College of Agriculturaland Life Sciences, University of Wisconsin, Madison; and bythe University of Wisconsin Research Committee with funds fromthe Wisconsin Alumni Research Foundation; and by the NationalScience Foundation Grant BMS 74-09611. (Received September 16, 1975; )     

Structure and Development of Stomata in Some Leptosporangiate Ferns

The structure and development of stomata are described for 17species of leptosporangiate ferns. In these species the maturestomata are anomocytic, diacytic, Pyrrosia(applied), tetracytic,suspended, or floating type. Stomata are present on both surfacesof floating as well as sub merged leaves of Azolla and Marsilea.In a few species twin stomata, arrested development, and persistentstomatal initials are present Floating stomata result from disintegrationof the anticlinal suspending wall in Pleopeltis, and by detachmentand displacement in Azolla pinnata. The development of stomatais haplocheilic, syndetocheilic, or syndetohaplocheilic. InCyathea spinulosa the guard cell nuclei divide amitoticallyand the resulting two daughter nuclei occupy the opposite polesof the guard cells     

Leaf and stem epicuticular wax structures in Lonicera species (Caprifoliaceae)

Epicuticular waxes are found on the surface of the plant epidermis as crystal structures which show morphological diversity and may be useful in plant systematics. The aim of this study was to recognise the diversity of the epicuticular wax cover on leaves and stems of Lonicera species (Caprifoliaceae) and to estimate the taxonomic value of wax traits. Adaxial and abaxial sides of the leaves and the stem surface in 35 taxa were investigated through a scanning electron microscope (SEM). The assessment was prepared on the basis of the presence or absence of basic types of wax structures and their dimensions, using categorical response analysis, multiple correspondence analysis and cluster analysis. In the analysed species, we found differences in the wax layer structure on the surfaces of the leaves and stems. Apart from the smooth layer, tubules and platelets can be found. Tubules are considerably more frequent than platelets. In many cases, the same plant part produces more than just one wax type. Our analysis indicates that wax structures are not very informative for the taxonomy of Lonicera, because we observed only a weak correspondence between the presence or absence of some types of wax tubules and the infrageneric classification of the genus. However, in particular cases these new data can be used for species identification.     

The zoeal stages and megalopa of Portunus rubromarginatus (Lanchester) (Decapoda: Portnnidae), reared in the laboratory

The present state of knowledge concerning Portunus larvae isreviewed, and the three zoeal and the megalopa stages of P.rubromarginatus are described and figured. Details of appendagesetation are tabulated. This species is unusual amongst knownPortunus spp. in having only three zoeal stages and, like otherPortunus spp. but in contrast with other Portuninae, it has4 + 4, or 4 + 1 + 4, setae on the posterior telson border. When compared with larvae of the five other Indo-West PacificPortunus species whose larvae are known P. rubromarginatus zoeaeare readily distinguished from all, except P. hastatoides, usingthe key features given by Kurata (1975). Comparison was madebetween first zoeae of these two species, and also of P. pelagicusand P. sanguinolentus, using larvae reared by the authors. Itwas found telson characters alone allow distinction betweenlarvae of these four species. These characters are tabulated. P. rubromarginatus megalopae differ from those known for congenitorsin having a large spine on the uchium of the first pereiopod,but not on the carpus, and in having relatively very small sternalcornuae. Several of these features disagree with those previously thoughtto characterise larval Portuninae or Portunus species.     

Light Distribution and Photosynthesis in Field Crops

In a new model of light distribution in field crops a parameters is the fraction of light passing through unit leaf layer withoutinterception. Radiation profiles measured with solarimetersand photocells give values of s from 0.7 for grasses to 0.4for species with prostrate leaves. Knowing s, leaf transmissionT and leaf-area index L the light distribution in a field cropmay be described by a binomial expansion of the form {s+(I-s)T)^L.To calculate crop photosynthesis at given light intensity thisexpansion is combined with two parameters describing the shapeof the light-response curve of single leaves. Finally, the assumptionthat solar radiation varies sinusoidally allows daily totalphotosynthesis to be estimated from daylength and insolation. The theory predicts about the same potential photosynthesisin a cloudy temperte climate with long days as in a more sunnyequatorial climate with short days. When L < 3 photosynthesisincreases as s decreases, i.e. as leaves become more prostrate;but when L > 5, photosynthesis increases as s increases,i. e. as leaves become more erect. Assuming that respirationis proportional to leaf area, estimated dry-matter productionagrees well with field measurements on sugar-beet, sugar-cane,kale, and subterranean clover. Estimates of maximum gross photosynthesis(for sugar-cane and maize) range from 60 to 9 g m^–2 day^–1depending on insolation.     

Lipids in Acanthodiaptomus denticomis during starvation and fed on three different algae

Variations in the levels of triglycerides, wax esters and polarlipids were determined in adults of the calanoid copepod Acanthodiaptomusdenticornis when freshly caught, starved or fed on the followingalgae: Anabaena spiroides, Cyclotella pseudostelligera and Pediastrumduplex. Over 7 days starvation, triglycerides and wax esterswere almost entirely used up by the copepods. Subsequent feedingover 20 days partially restored triglycerides but restored onlya relatively small fraction (<20%) of wax esters in the animals.Differences in the lipid restoration were found: the restoredtriglyceride level was higher in animals feeding on Cyclotellapseudostelligera or Pediastrum duplex than in those feedingon Anabaena spiroides. Fatty acid composition of neutral lipidswas closely linked to fatty acid composition of algae. The resultssuggest that lipid and fatty acid contents of Acanthodiaptomusdenticornis are good indices of the copepod's nutritional statusand short-term (0–20 days) feeding history.     

Performance of adult psyllids in no-choice experiments on juvenile and adult leaves of Eucalyptus globulus

The presence of glaucous juvenile leaves and glossy adult leaves in the canopy of the heteroblastic plant Eucalyptus globulus Labill., is a source of within-tree variation that affects herbivory by three psyllid species (Ctenarytaina eucalypti Maskell, C. spatulata Taylor and Glycaspis brimblecombei Moore) (Homoptera, Psyllidae). In no-choice field experiments with adult female psyllids in clip-on cages, we compared (1) leaf-settling, honeydew production, and survival of the Ctenarytaina species on juvenile and adult leaves of E. globulus, (2) leaf-settling and survival of G. brimblecombei on juvenile and adult leaves, (3) leaf-settling and survival of the three species on waxy (untreated) juvenile leaves and de-waxed (rubbed) juvenile leaves, and (4) leaf-settling and survival of C. spatulata on juvenile leaves from which wax was repeatedly removed. Leaf-settling by C. eucalypti was significantly greater on juvenile than adult leaves, however, honeydew production and survival were equal on both leaf types. In contrast, leaf-settling, honeydew production, and survival by C. spatulata were significantly greater on adult than juvenile leaves. Similarly, leaf-settling and survival by G. brimblecombei were significantly greater on adult than juvenile leaves. Wax removal from juvenile leaves significantly increased leaf-settling and survival of C. spatulata and G. brimblecombei. Although wax removal decreased leaf-settling by C. eucalypti, it did not affect survival. Repeated removal of regenerating wax from juvenile leaves did not affect leaf-settling or survival of C. spatulata. These results suggest that the epicuticular wax of juvenile leaves plays a role in resistance to C. spatulata and G. brimblecombei, however other unknown factors are probably also involved.     

Major Element Composition of Epidermal and Mesophyll Tissues2Commelina Communis L. and Vicia Faba L.: Some Further Considerations of the Role of Ions in Stomatal Functioning

Epidermal and mesophyll tissues of Commelina communis L. andVicia faba L. were analysed by atomic absorption spectrometryfor the major plant inorganic cations and anions (K, Na, Ca,Mg, P, NO₃-N, Cl) when stomata of the leaf were open and closed.Water-soluble and residual levels of the elements were estimatedand a charge balance of the soluble fraction made. The major portion of K, Na, Cl, and P was extracted in the water-solublefraction of the epidermal and mesophyll tissues of both species.In both species the bulk of Ca remained in the insoluble residueof the epidermis whereas in mesophyll tissue it was equallydistributed be-between the two fractions in C. communis butmainly in the insoluble residue in V. faba. Magnesium was predominantlyfound in the water-soluble fraction of V. faba mesophyll tissueand distributed approximately equally between the two fractionsin the epidermal tissue. In C. communis Mg was slightly moreabundant in the water-soluble fraction of both mesophyll andepidermis. In both species no statistically significant differences inthe levels of the elements could be detected between epidermaland mesophyll tissues from leaves with open stomata and thesame tissues from leaves with closed stomata, suggesting thatthere was no major flux of ions between mesophyll and epidermisduring stomatal movements. Regardless of whether the stomata were open or closed, therewere considerably more water-soluble inorganic cations thananions present in all tissues of both species with K being themajor cation and Cl being the major anion. In V.faba and C-communis epidermis there was 49–53 per cent and 56%68per cent excess cation respectively. In the mesophyll tissuethe excess cation was 63–75 per cent and 75%78 per centin V.faba and C. communis respectively. When the partitioning of the levels of the elements betweenepidermis and mesophyll of a leaf is considered, except forNO₃-N in both species and Na in V. faba, 20 per cent or lessof each element was present in the epidermis.     

Flavan-3-ols in Trichomes, Pistils and Phelloderm of Some Tree Species

Tissues from nine tree species were examined histochemicallyfor the presence of flavan-3-ols including the catechins. Itwas possible to stain these phenolics selectively with p-dimethylaminocinnamaldehyde(DMACA) and to show that they were located in trichomes, pistilsand shoot phelloderm. The staining intensity of the tissueswas categorized into four groups. The flavan-3-ols were extractedfrom three tree species and the diverse components were distinguishedusing a combination of HPLC and chemical reaction detection(CRD). Twelve flavan-3-ols were isolated from pistils of Tiliagrandifolia and 32 from leaves of Acer platanoides. The hairsof the leaves of dormant buds from Aesculus hippocastanum yielded13 components. Epicatechin and ( + )-catechin were present inall three species. Trees, trichomes, pistils, phelloderm, histochemistry, HPLC, CRD