Quantitative comparison of foliage development amongDryopteris monticola,D. tokyoensis and a putative hybrid,D. kominatoensis in Northern Japan

Developmental leaf architecture was quantitatively described in terms of measurements of various parameters on leaf blade from different size of sporophytes inDryopteris monticola, D. tokyoensis and a putative hybrid,D. kominatoensis in the natural site of Hokkaido, to compare the ontogenetic differentiation in foliage structure among allied ferns. The morphological stage of leaf and sporophyte was tentatively quantified by the number of midrib branches of the leaf (NV, number of veins), which exhibited a significant correlation to the leaf-shape complexity from a circle (DI=marginal length/2×(3.14×square)^1/2) of leaf blade. D. kominatoensis showed intermediate values between others in following characters; DI increase, maximum NV (also blade length), maximum number of costa branches of pinnae (NVMP), number of costa branches of the lowest pinna (NVLP), difference between NVMP and NVLP (NVMP-NVLP), during heteroblastic leaf development. A larger number of leaves per sporophyte was found inD. kominatoensis than in others. The fertility rate (%) and initiation of fertility (IF) in the relative developmental stage (RDS) ofD. kominatoensis shifted to that ofD. tokyoensis, while the order of pinnae with NVMP shifted to that ofD. monticola. Even in the intermediate characters inD. kominatoensis, slight shifts in characters to those of putative parents were found during heteroblastic leaf development. Contribution No. 3145 from the Institute of Low Temperature Science, Hokkaido University.     

THE ORGANIZATION OF THE VASCULAR SYSTEM IN THE STEMS OF THE NYMPHAEACEAE. I. NYMPHAEA SUBGENERA CASTALIA AND HYDROCALLIS

The vascular system in the stems of Nymphaea odorata and N. mexicana subgenus Castalia, and N. blanda subgenus Hydrocallis consists of continuing axial stem bundles with eight being the usual number. The stem bundles are concentric and xylem maturation is mesarch. Xylem elements consist of tracheids with spirally or weakly reticulated secondary wall thickenings. The phloem is made up of companion cells and short sieve tube members with simple sieve plates that are nearly transverse. At the node each leaf is supplied with two lateral leaf traces and a median leaf trace. A root trace is also present and supplies a series of adventitious roots borne on the leaf base. Flowers and vegetative buds develop directly from the apical meristem and occupy leaf sites in a single genetic spiral. Each flower or vegetative bud is related to a leaf through specific spatial and vascular association. The related leaf is separated from the related flower by three members of the genetic spiral and occupies an adjacent orthostichy. Vascular tissue for the related flower arises from the inner surfaces of the four stem bundles supplying leaf traces to the related leaf and extends through the pith to the flower or vegetative bud via a peduncle fusion bundle. The vascular system organization in the investigated species of Castalia and Hydrocallis is not typically monocotyledonous or dicotyledonous, nor can it be considered transitional between them. The ontogeny of the vascular system is similar to typical dicotyledons and the investigated species of Nymphaea can, therefore, be considered to represent highly specialized and modified dicotyledons.     

Tissue-specific antigens secreted by suspension-cultured callus cells of Prunus avium L.

A number of antigenic components are secreted into the medium by P. avium callus cells derived from different tissues and grown in suspension culture. These antigens have been detected using antiserum raised in rabbits to a protein fraction secreted by P. avium leaf callus. One antigen is specific to leaf tissue and is secreted by callus cells derived from stem, pistil and anthers as well as leaves. A second antigen is, in intact organs, restricted to styles of a particular self-incompatibility (S) genotype, but is also secreted by callus cells derived from the leaf. Another antigen, apparently not organ-specific, is secreted by all calli tested, including Rosa (cv. Paul's Scarlet).     

酸枣叶片结构可塑性对自然梯度干旱生境的适应特征

叶片是植物体暴露于环境中面积最大的器官,其最易感知环境变化而发生形态和结构上的改变。为探究植株叶片结构对不同生境的适应机理,研究以生长在烟台-石家庄-宁夏-新疆不同地域气候条件形成的自然梯度干旱环境中的酸枣为试验材料,应用植物显微技术研究酸枣叶片的结构的可塑性对不同自然梯度干旱环境的适应特征。结果表明:酸枣叶表皮着生有表皮毛,表皮细胞外覆有角质层与蜡质。叶肉为全栅型,栅栏组织发达,海绵组织退化,叶肉中有晶体及大量的分泌细胞。从烟台至新疆随生境梯度干旱加剧,酸枣叶片叶面积逐渐变小,叶片厚度依次增加,叶表皮角质层加厚,且上角质层厚度大于下角质层厚度;叶片上下表皮细胞长径及短径先增后降,栅栏组织总厚度和密度依次增大、层数减少,各层栅栏组织细胞的长径逐渐增加。叶脉薄壁细胞相对厚度逐渐减小,导管管径增大,晶体(草酸钙晶体)数增多。在梯度干旱环境中酸枣植株通过减小叶面积、提高栅栏组织密度、增加叶片及角质层厚度降低蒸腾作用,减少水分散失;通过增大导管管径提高水分利用率;通过增加晶体数量提高叶片机械性能,改变细胞的渗透势、提高吸水和保水能力。上述叶片结构的变化是酸枣植株长期对不同自然梯度干旱生境的适应特征。由此可知,叶片形态结构中叶面积、叶片厚度、角质层及叶肉组织(栅栏组织)随环境变化的可塑性较大。     

Coordination of cell proliferation and cell expansion in the control of leaf size in Arabidopsis thaliana

Size is an important parameter in the characterization of organ morphology and function. To understand the mechanisms that control leaf size, we previously isolated a number of Arabidopsis thaliana mutants with altered leaf size. Because leaf morphogenesis depends on determinate cell proliferation, the size of a mature leaf is controlled by variation in cell size and number. Therefore, leaf-size mutants should be classified according to the effects of the mutations on the cell number and/or size. A group of mutants represented by angustifolia3/grf-interacting factor1 and aintegumenta exhibits an intriguing cellular phenotype termed compensation: when the leaf cell number is decreased due to the mutation, the leaf cell size increases, leading to compensation in leaf area. Several lines of genetic evidence suggest that compensation is probably not a result of the uncoupling of cell division from cell growth. Rather, the evidence suggests an organ-wide mechanism that coordinates cell proliferation with cell expansion during leaf development. Our results provide a key, novel concept that explains how leaf size is controlled at the organ level.     

THE ORGANIZATION OF THE VASCULAR SYSTEM IN THE STEMS OF THE NYMPHAEACEAE. III. VICTORIA AND EURYALE

Organization of the stem vascular system was analyzed in Victoria species and Euryale ferox. The stem vascular system consists of a number of concentrically-organized continuing axial stem bundles. At the node each leaf is supplied with a root trace, two lateral leaf traces, and a median leaf trace. A peduncle fusion bundle is also present at each node. The peduncle fusion bundle supplies vascular tissue to the median leaf trace and to the peduncle trace. Flowers are nonmedian axillary but have specific vascular, spatial, and developmental relationships to leaves in a manner that resembles the genus Nymphaea. On the basis of the analysis of the stem vascular system, Victoria and Euryale are more similar to each other than to Nymphaea. However, the vascular system in Victoria and Euryale is similar enough to Nymphaea to suggest that Nymphaea, Victoria, and Euryale form a natural taxon of unique angiosperms. The organization of the stem vascular system in Victoria and Euryale is dicotyledonous.     

Population Tendencies of Pseudomonas cichorii and P. syringae pv. garcae in Young and Mature Coffee Leaves

The population tendencies of Pseudomonas cichorii and P. syringae pv. garcae in young and mature coffee leaves were determined by inoculating streptomycin resistant bacterial cells from 24 h cultures into young and mature coffee leaves. The leaves were then sampled daily for 5 days and the number of bacterial cells per g of leaf tissue was determined. Pseudomonas cichorii increased in mature leaves only while P. syringae pv. garcae increased in young leaves. Symptom development was dependent on the presence of a large number of bacterial cells in the host tissue and coincided with the maximum content of bacterial cells in the leaf.     

Potential of Ulocladium atrum for biocontrol of onion leaf spot through suppression of sporulation of Botrytis spp.

Epidemics of onion leaf spotcaused by Botrytis spp. depend onnecrotic leaf tissue for inoculum build up inthe crop. Ulocladium atrum Preuss. is astrong competitor on necrotic above-groundplant tissues. The potential of the antagonistto reduce colonisation of necrotic leaf tissueby Botrytis spp. and subsequentsporulation was studied in two fieldexperiments. U. atrum colonised necrotictissues and consistently reduced thesporulation of fungal competitors. Althoughincidence of Botrytis spp. was low,significantly lower spore loads of Botrytis spp. were found on spore trapslocated within U. atrum treated onionplots as compared to untreated control plots.The number of leaf spots caused by Botrytis spp. was low in both fieldexperiments but was significantly reduced by60% after U. atrum applications in thesecond experiment. Spraying of the fungicideRonilan resulted in the same control level.Results show that U. atrum has apotential for biological control against diseases caused by Botrytis spp. in onions.     

Morphological and anatomical analyses of rheophytic Rhododendron ripense Makino (Ericaceae)

The comparative morphology and anatomy of the leaves of the rheophytic Rhododendron ripense and the closely related inland species Rhododendron macrosepalum were examined. The leaf of R. ripense is thinner than that of R. macrosepalum, with leaf length to width ratios (leaf index) of 2.92 and 1.91, respectively. Moreover, the leaf of R. ripense consists of fewer cells than the leaf of R. macrosepalum, suggesting stenophyllization of R. ripense caused by the decreased number of cells. In addition, leaf thickness and the number of stomata per leaf of R. ripense were significantly greater than those of R. macrosepalum, but the density of the short glandular pilose hairs on the leaf of R. ripense was lower. The observed morphological differences between the two species may be explained by certain aspects of the riparian environment, such as high irradiation and frequent flooding after heavy rainfall, to which R. ripense is exposed.     

BRANCH GEOMETRY AND EFFECTIVE LEAF AREA: A STUDY OF TERMINAUA-BRANCHING PATTERN. 1. THEORETICAL TREES

Single lateral branches and branch tiers of Terminalia catappa L. are simulated and drawn by computer. Leaf clusters on the branches are approximated by discs, and the effective leaf areas are determined by use of Dirichlet domains. Theoretical optimal branching angles which produce the maximum effective leaf area are obtained from simulations. Symmetrical and asymmetrical branching angles are contrasted; the latter characterize real trees. Varying leaf disc radius and ratio of branch-unit lengths affects optimal branching angles, as does the symmetry of a tier of five branches. Leaf area indices for individual branches and branch tiers are given for all simulations. The number of branches in a tier has a major effect on leaf area index and effective leaf area. The theoretical optimal branching angles of many simulations are very close to the values observed in real trees of T. catappa. We conclude that the observed branching angles and number of branches in a tier of this species optimize light interception within constraints of a fixed pattern of branching, one that is widespread among tropical trees.     

EVOLUTION OF LEAF ARCHITECTURE IN THE CHAPARRAL SPECIES FREMONTODENDRON CALIFORNICUM SSP. CALIFORNICUM (STERCULIACEAE)

The chaparral species Fremontodendron californicum ssp. californicum and the cloud forest species Cheirostemon platanoides arose from a common mesophytic stock. The leaf of C. platanoides is proposed as a model for the ancestral leaf and provides an architectural baseline allowing identification of the types and relative magnitudes of morphological and anatomical modifications which have occurred in the leaf of F. californicum. The leaf of F. californicum reflects intense selection for reduced surface area; however, both deletion and addition of lobes has occurred. Vein density has increased due to a greater number of more highly branched terminal veinlets. Mechanical structures, i.e., sclerenchyma, cuticle, show a quantitative reduction; whereas, water storage tissue, i.e., mucilage cells, has been augmented at the expense of spongy mesophyll. The leaf has become weakly isolateral and the number of palisade strata has increased. No increase in the volume of palisade tissue per unit volume of mesophyll is apparent due to a reduction in palisade cell length and palisade packing density. Total leaf thickness has not increased. The indumentum shows selection for non-living, pedestalled stellate trichomes which form a transpiration-limiting canopy above the stomata. Stomatal density has decreased while guard cell dimensions have become larger. Some structural modifications in F. californicum appear to have evolved directly in response to long-term water stress, others seem more directly related to leaf diminution. Xeroplastic changes in foliar structure are in some cases unreliable indicators of ultimate xeromorphic modifications arising in an evolutionary context.     

Oviposition preference and neonate performance of Mnesampela privata in relation to heterophylly in Eucalyptus dunnii and E. globulus

Abstract

• 1 The autumn gum moth, Mnesampela privata, is an endemic Australian geometrid that utilizes a number of species within the genus Eucalyptus as hosts. Based on field observations, the moth is thought to be leaf‐type specific for juvenile as opposed to adult eucalypt foliage.
• 2 Laboratory binary choice assays of the oviposition preference of host novice M. privata confirmed that eggs were more likely to be laid upon juvenile rather than adult foliage of Eucalyptus dunnii and two subspecies of E. globulus. This oviposition preference was not influenced by differences in leaf size or adherence to leaves by ovipositing moths. The high specific leaf weights common to adult leaves were associated with reduced oviposition.
• 3 Although neonates fed on both juvenile and adult leaves of most of the trees studied, performance was greater on juvenile as opposed to adult foliage. Juvenile leaves typically had lower specific leaf weights and were nutritionally superior to their adult counterparts. Specific leaf weights above 0.236 mg/mm² (associated with low water, i.e. = 56.5%, and nitrogen, i.e. = 1.23%, contents) were associated with reduced larval performance. Younger adult leaves, those with lower specific leaf weights, allowed slightly greater larval consumption.
• 4 When ovipositing, this eucalypt‐specific moth discriminates between leaf types of its heterophyllous hosts in favour of types with the lowest specific leaf weight. Less tough leaf types, which are also higher in nitrogen, enable neonates to attain larger body weights.

     

Primulina maciejewskii sp. nov. (Gesneriaceae) from Guangdong,China

Primulina maciejewskii F. Wen, R.L. Zhang & A.Q. Dong, a new species of Primulina (Gesneriaceae) from Guangdong, China, is described and illustrated. It is similar to P. lobulata and P. danxiaensis in leaf and flower shape, but can be distinguished by bract shape, peduncle, pedicel, and bract size, filament and anther indumentum, and number of bracts, staminodes and stigma.     

Autochthonous leaf assemblages as records of deciduous forest communities: an actualistic study

How well do autochthonous leaf assemblages reflect live plant communities? How do leaf assemblages accumulating over different time scales compare in paleoecologic information content? Forest-floor leaf assemblages accumulating over ten-day intervals (referred to here as short-term assemblages) and over a five-month season of leaf abscission (referred to here as a long-term assemblage) were compared with the surrounding community in a modern temperate deciduous forest in northern Ohio. Leaf number in the long-term leaf assemblage is strongly correlated with the abundance of taxa (stem number) around the accumulation site and weakly correlated with both average taxon size (stem circumference) and average taxon distance from the accumulation site. Of the variance in leaf number, 45% is explained solely by stem number and 67% by stem number and average distance together. Average size explains an insignificant amount of the variance in leaf number. Like the long-term assemblage, leaf number in the short-term leaf assemblages is usually strongly correlated with stem number and usually weakly correlated with average taxon size and average taxon distance. However, these patterns are not consistent, and the correlations are highly variable. Similarly, there is high variability in the degree to which stem number, average taxon size and average taxon distance account for variance in leaf number. Short-term leaf assemblages are characterized by great fluctuations in taxonomic relative abundance, caused by seasonal variation in the timing and rate of leaf abscission among taxa. While autochthonous leaf assemblages accumulating over several months can reflect the surrounding community with fair accuracy, leaf assemblages accumulating over shorter time spans are inconsistent records of the surrounding community. The depositional circumstances producing short-term assemblages (i.e. event burial) may result in well-preserved specimens, but community data from such assemblages should be treated with caution and, if possible, compared with data from contemporaneous long-term assemblages.Paleobotany, taphonomy, actualism, paleocommunity reconstruction, time-averaging. Keith H. Meldahl, Damon Scott and Karen Carney, Department of Geology, Oberlin College, Oberlin, Ohio, 44074, USA; 6th June, 1994; revised 8th February, 1995.     

Rheum neyshabourense sp. nov. (Polygonaceae) from Iran

Rheum neyshabourense Baradaran & Jafari from northeastern Iran (Khorassan Razavi Province) is newly described. It is similar to R. ribes but differs in the number of prominent leaf veins, the position of the joint on the pedicle, fruit shape, epidermal cell shape and the type of stele in the inflorescence axis. A key to Rheum species in Iran is also provided.     

Correlation between leaf growth variables suggest intrinsic and early controls of leaf size in Arabidopsis thaliana

Leaf development is affected by both internal (genetic) and external (environmental) regulatory factors. The aim of this work was to investigate how leaf growth variables are related to one another in a range of environments. The leaf growth variables of wild-type Arabidopsis thaliana and leaf development mutants (ang4, ron2-1, elo1, elo2 and elo4) were studied under different incident light treatments (light and shade). The leaves studied were altered in various leaf development variables, such as the duration of expansion, relative and absolute expansion rates, epidermal cell size, epidermal cell number and initiation rate. Final leaf area was correlated to maximal absolute leaf expansion rate and cell number, but not to duration of leaf expansion or cell size. These relationships were common to all studied genotypes and light conditions, suggesting that leaf size is determined early in development. In addition, the early variables involved in leaf development were correlated to one another, and initial relative expansion rate was negatively correlated to the duration of expansion. These relationships between the leaf development variables were used to construct a conceptual model of leaf size control.     

Functional consequences of stenophylly for leaf productivity: comparison of the anatomy and physiology of a rheophyte, Farfugium japonicum var. luchuence, and a related non-rheophyte, F. japonicum (Asteraceae)

We investigated the anatomical and physiological characteristics of stenophyllous leaves of a rheophyte, Farfugium japonicum var. luchuence, and sun and shade leaves of a non-rheophyte, F. japonicum, comparing three different populations from coastal, forest floor, and riparian habitats. Light adaptation resulted in smaller leaves, and riparian adaptation resulted in narrower leaves (stenophylly). The light-saturated rate of photosynthesis (P _max) per unit leaf area corresponded to the light availability of the habitat. Irrespective of leaf size, the P _max per unit leaf mass was similar for sun and shade leaves. However, the P _max per mass of stenophyllous leaves was significantly lower than that of sun and shade leaves. This was because the number and size of mesophyll cells were greater than that required for intercellular CO₂ diffusion, which resulted in a larger leaf mass per unit leaf area. Higher cell density increases contact between mesophyll cells and enhances leaf toughness. Stenophyllous leaves of the rheophyte are frequently exposed to a strong water flow when the water level rises, suggesting a mechanical constraint caused by physical stress.     

Capparis dongvanensis sp. nov. (Capparaceae) from Vietnam

Capparis dongvanensis (Capparaceae) is described as a new species and illustrated from Ha Giang Province of Vietnam. It is morphologically similar to C. lanceolaris and C. fengii, but differs in the number of flowers on peduncles, length of spine and petiole, apex of the leaf, type of inflorescence, petal color, cylindrical ovary without any beak, fruit shape and number of seeds per fruit. Diagnostic morphological characters along with pollen and seed SEM images of C. dongvanensis and allied species are provided. Its ecology, habitat and conservation status are also described.     

Salt-stress effects on avocado rootstock growth. I. Establishing criteria for determination of shoot growth sensitivity to the stress

The mechanisms of shoot growth inhibition under salt-stress are not yet understood. Comparative evaluation of growth tolerance level of plant material used for mechanistic studies into stress effect on growth processes is a critical step towards establishing a plant model system for studies of stress effects on growth.In the present study, numerous vegetative shoot-growth parameters were evaluated as criteria for determination of shoot growth sensitivity of avocado rootstocks (Persea americana Mill.) to salt-stress. Seven different West-Indian rootstocks were investigated for their growth response to the stress. The plants, grown in 50 L soil-filled containers, were treated with 4 mM Na and 6 mM Cl (control) or 18 mM Na and 20 mM Cl (salt) for a period of 3 years. Changes in trunk diameter, branch diameter, number of new branches, branch fresh weight (FW) and dry weight (DW), leaf length, leaf area, leaf number, leaf FW and DW and distribution of the leaf population into size classes, were quantified during the season of rapid shoot growth, and used for grading growth sensitivity.The seven rootstocks studied were ranked according to the sensitivity of their vegetative growth to the stress. The order of sensitivity was found to be similar when the ranking was based on changes in DW and FW deposition per branch, cumulative leaf area and leaf weight per branch, or branch stem weight. Stress effects on leaf FW deposition were similar to the effect on total branch FW. Stress effects on branch stem FW were closely related to total branch DW deposition. Inhibition of cumulative leaf area per branch was less sensitive to the stress than deposition of FW or DW biomass. Biomass production per branch, or alternatively leaf biomass production per branch, is suggested as a practical parameter for evaluation of avocado rootstock shoot growth sensitivity to salt-stress.     

Kinetin regulates plant growth and biochemical changes during maturation and senescence of leaves,flowers, and pods of <Emphasis Type="Italic">Cajanus cajan</Emphasis> L.

Aspects of plant growth such as height, branch number, leaf number, leaf area, pod area, 100-seed mass, etc., were correlated with biochemical changes such as contents of chlorophyll (Chl), proteins, DNA, and RNA, and protease activity during development and senescent phases in leaves, flowers, and pods of Cajanus cajan L. cv. UPAS-120 after treatments with kinetin (Kn). A significant increase was noticed in branch number, leaf number, leaf area, and seed mass while other growth processes registered a small increase after Kn application. Effectiveness of 5 μM Kn was also noticed in minimizing the loss of Chls, proteins, and nucleic acids as well as reducing the protease activity during maturity and senescence. Chl a/b ratio maintained a high value up to 30-d followed by a decline in leaves while flowers registered much lower ratio at 20-d-age. Pods were unique in having relatively lower ratio of Chl a/b in comparison to leaves.