Search

AbstractAs a key component of lightweight impact-protection devices, thin-walled structures with marvelous specific energy absorption (SEA) have attracted wide attention. Inspired by leaf venation in royal water lily, a hybrid multi-cell thin-walled structure with fractal and hierarchy architectures is proposed. Its crashworthiness is compared with traditional cylinder by combining finite element simulation and experiment, and corresponding mechanism is revealed. The results show that due to more folds and smaller folded wavelength, the venation-like structure exhibits better crashworthiness than the cylinder. Increasing the initial bifurcation number and hierarchy level of venation-like structure will introduce massive corner constraints, especially the hierarchy level, which benefits folding deformation and improving effectively crashworthiness. Further, a fully hybrid venation-like structure is designed by introducing gradient architecture. With the increase of length-gradient or thickness-gradient, the SEA first linearly increases and then slightly decreases. Under the optimal length-gradient, majority of area exhibits high internal energy. By taking the gradient length and thickness simultaneously, a kind of hybrid deformation mode with quasi-uniform small folding and overall large folding appears, where multiple small folds interacts strongly, achieving good load-bearing capacity. The optimal SEA of venation-like structure is 81.5% higher than that of the cylinder. [ABSTRACT FROM AUTHOR]

Nature-inspired microfluidic networks are revolutionizing microphysiological systems, allowing for the precise emulation of human physiology. This article delves into the fabrication techniques of leaf-venation-inspired (LVI) microfluidic networks and explores their transformative applications in organ-on-a-chip and tissue engineering, showcasing their pivotal role in advancing biomedical research. [ABSTRACT FROM AUTHOR]

The classification of Mussaenda L. has been controversial due to the complex interspecific variation and hybridization within the genus. In order to explore the taxonomical significance of leaf venation characteristics between Mussaenda and its relative genera (Schizomussaenda Li and Psudomussaenda Wernham), and to provide data for the identification, development and utilization when they were regarded as the medical and garden plant resources, the leaf venation characteristics of 22 species of this group were observed by using the cleaning method. The cluster analysis was carried out based on the characteristics of leaf venation, and a classification key of the species was compiled. The results were as follows: (1) The characteristics of the leaf venation of Mussaenda and its relative genera had consistency, which were mainly reflected on that the primary veins were all pinnate, the frequency of inter-secondary veins was less than one per areolation, the angles between the major secondary veins and the midveins were acute, the tertiary veins were mostly penetrating, and the arrangement of the areolation were all irregular. (2) The characteristics of the leaf venation with taxonomic value among genera or species within genera included the type of major secondary vein venation type, the angle between major secondary vein and midvein, the major secondary vein spacing, the connection between major secondary vein and midvein, the existence of inter-secondary vein and intramarginal secondary vein, the penetration type of intercostal tertiary vein, the type of quaternary vein, the branching of freely ending veinlet, and the areole development. (3) According to the cluster analysis, 22 species of this group were clustered into 12 branches, and Schizomussaenda and Psudomussaenda were not clustered into one branch respectively, showing a relatively close genetic relationship. In conclusion, the leaf venation characteristics of Mussaenda and its related taxa can provide new information for the classification of the plants. [ABSTRACT FROM AUTHOR]

Summary: We investigated the mining mode of insect feeding, involving larval consumption of a plant's internal tissues, from the Middle Jurassic (165 million years ago) Daohugou locality of Northeastern China. Documentation of mining from the Jurassic Period is virtually unknown, and results from this time interval would address mining evolution during the temporal gap of mine–seed plant diversifications from the previous Late Triassic to the subsequent Early Cretaceous.Plant fossils were examined with standard microscopic procedures for herbivory and used the standard functional feeding group–damage‐type system of categorizing damage. All fossil mines were photographed and databased.We examined 2014 plant specimens, of which 27 occurrences on 14 specimens resulted in eight, new, mine damage types (DTs) present on six genera of bennettitalean, ginkgoalean, and pinalean gymnosperms.Three conclusions emerge from this study. First, these mid‐Mesozoic mines are morphologically conservative and track plant host anatomical structure rather than plant phylogeny. Second, likely insect fabricators of these mines were three basal lineages of polyphagan beetles, four basal lineages of monotrysian moths, and a basal lineage tenthredinoid sawflies. Third, the nutrition hypothesis, indicating that miners had greater access to nutritious, inner tissues of new plant lineages, best explains mine evolution during the mid‐Mesozoic. See also the Commentary on this article by McLoughlin & Santos, 242: 2391–2393. [ABSTRACT FROM AUTHOR]

The dataset contains leaf venation architecture and functional traits for a phylogenetically diverse set of 122 plant species (including ferns, basal angiosperms, monocots, basal eudicots, asterids, and rosids) collected from the living collections of the University of California Botanical Garden at Berkeley (37.87° N, 122.23° W; CA, USA) from February to September 2021. The sampled species originated from all continents, except Antarctica, and are distributed in different growth forms (aquatic, herb, climbing, tree, shrub). The functional dataset comprises 31 traits (mechanical, hydraulic, anatomical, physiological, economical, and chemical) and describes six main leaf functional axes (hydraulic conductance, resistance and resilience to damages caused by drought and herbivory, mechanical support, and construction cost). It also describes how architecture features vary across venation networks. Our trait dataset is suitable for (1) functional and architectural characterization of plant species; (2) identification of venation architecture‐function trade‐offs; (3) investigation of evolutionary trends in leaf venation networks; and (4) mechanistic modeling of leaf function. Data are made available under the Open Data Commons Attribution License. [ABSTRACT FROM AUTHOR]

Leaf morphoanatomy can provide useful information for the taxonomy of morphologically similar species or the recognition of infraspecific taxa. Here, we evaluated the taxonomic utility of leaf morphological and anatomical characters for the recognition of distinct morphologies currently placed under Oxalis polymorpha Mart. ex Zucc., a highly polymorphic species of Oxalis from the Brazilian Atlantic Forest. We analyzed leaves of 13 specimens gathered from five populations throughout the species' geographic distribution. Leaf samples were analyzed under light and scanning electron microscopy. We observed differences in the leaf blade venation patterns, in the indumentum of petioles and leaf blades, in the pulvinar vascular tissue configuration, and in the midrib tissue organization. The variation in these characters allowed us to recognize four different morphotypes among these samples. These morphotypes are geographically disjunct and differ among each other in additional morphological features, such as leaf arrangement along the stem, leaflet shape, inflorescence position, petal color, and fruit shape. Oxalis polymorpha is a good candidate for investigating if phylogenetic relationships support recognition of each of its morphotypes at the species level. [ABSTRACT FROM AUTHOR]

Background and Aims Ferns are the second largest group of vascular plants and are distributed nearly worldwide. Although ferns have been integrated into some comparative ecological studies focusing on hydathodes, there is a considerable gap in our understanding of the functional anatomy of these secretory tissues that are found on the vein endings of many fern leaves. In this study, we aimed to investigate the phylogenetic distribution, structure and function of fern hydathodes. Methods We performed a global review on fern hydathodes and their phylogenetic distribution, carried out an ancestral character state reconstruction, and studied the structure, guttation and elemental composition of salt residues of eight species, and the diurnal patterns of xylem pressure of two species. Key Results Hydathodes are known from 1189 fern species, 92 genera and 19 families of 2 orders, Equisetales and Polypodiales. Stochastic character mapping indicated multiple gains and losses of hydathodes at the genus level, occurring especially during the last 50 million years of fern evolution. Hydathodes were located on the adaxial leaf surface and characterized by a cytoplasm-rich, pore-free epidermis, and became functional for several weeks after nearly complete leaf expansion. In two species, positive xylem pressure built up at night, potentially facilitating guttation. Guttation fluid was rich in Ca and often Si, but also contained P, Mg, Na and Al. Conclusions Stochastic character mapping and the structural and functional diversity of hydathodes indicate multiple origins, and their presence/absence in closely related taxa implies secondary losses during fern evolution. Positive xylem pressure and high air humidity play an important role as drivers of guttation. Hydathodes may contribute to the regulation of leaf nutrient stoichiometry by the release of excessive compounds and minerals other than waste products, but the presence of essential chemical elements in salt residues also indicates possible leakage. [ABSTRACT FROM AUTHOR]

Premise: Angiosperm leaves present a classic identification problem due to their morphological complexity. Computer‐vision algorithms can identify diagnostic regions in images, and heat map outputs illustrate those regions for identification, providing novel insights through visual feedback. We investigate the potential of analyzing leaf heat maps to reveal novel, human‐friendly botanical information with applications for extant‐ and fossil‐leaf identification. Methods: We developed a manual scoring system for hotspot locations on published computer‐vision heat maps of cleared leaves that showed diagnostic regions for family identification. Heat maps of 3114 cleared leaves of 930 genera in 14 angiosperm families were analyzed. The top‐5 and top‐1 hotspot regions of highest diagnostic value were scored for 21 leaf locations. The resulting data were viewed using box plots and analyzed using cluster and principal component analyses. We manually identified similar features in fossil leaves to informally demonstrate potential fossil applications. Results: The method successfully mapped machine strategy using standard botanical language, and distinctive patterns emerged for each family. Hotspots were concentrated on secondary veins (Salicaceae, Myrtaceae, Anacardiaceae), tooth apices (Betulaceae, Rosaceae), and on the little‐studied margins of untoothed leaves (Rubiaceae, Annonaceae, Ericaceae). Similar features drove the results from multivariate analyses. The results echo many traditional observations, while also showing that most diagnostic leaf features remain undescribed. Conclusions: Machine‐derived heat maps that initially appear to be dominated by noise can be translated into human‐interpretable knowledge, highlighting paths forward for botanists and paleobotanists to discover new diagnostic botanical characters. [ABSTRACT FROM AUTHOR]

With the aim of recognizing and identifying both fertile and sterile specimens of Ocotea from the Brazilian state of Bahia, we analyzed the leaf venation pattern of 55 species, 21 of them being described and illustrated for the first time. A dichotomous identification key was built from a matrix of 12 venation characters and 36 states, which allowed to distinguish the taxa. [ABSTRACT FROM AUTHOR]

With the aim of recognizing and identifying both fertile and sterile specimens of Lauraceae from the Reserva Natural Vale, Linhares, we analyzed the leaf venation pattern of 20 species belonging to 11 genera. The venation patterns of 12 species are described and illustrated for the first time here. A dichotomous identification key was built from a matrix of 12 venation characters with 38 states, which allowes to distinguish the taxa. [ABSTRACT FROM AUTHOR]

Leaf venation is an important trait used for specifying and grouping plants. In the present study leaf venation types of 30 Saxifraga L. species, found in Indian Western Himalaya, were studied. Out of these, leaf venation patterns of 20 species were not previously studied. In total, five major types of leaf venations viz. acrodomous (perfect-basal; perfect-suprabasal; imperfect-suprabasal), camptodromous (eucamptodromous), campylodromous, hyphodromous, and palinactinodromous – were recorded. Section Micranthes showed palinactinodromous; section Ciliatae showed mainly acrodromous; section Mesogyne showed palinactinodromous; and sect. Porphyrion showed acrodromous, eucamptodromous and hyphodromous types of venations. Palinactinodromous venation type was found to be the ancestral type. Further molecular study is needed to be done to solve the taxonomic complexity of the genus. [ABSTRACT FROM AUTHOR]

With the aim of recognizing and identifying both fertile and sterile specimens of Lauraceae from the Brazilian state of Bahia, we analyzed the leaf venation pattern of 56 species belonging to 14 genera (excluding Ocotea), 30 of them described and illustrated for the first time. A dichotomous identification key was built from a matrix of 12 venation characters and 36 states, which allowed to distinguish the taxa. [ABSTRACT FROM AUTHOR]

In this research, the vein architecture of leaves belonging to 14 plant species having different morphological features were comparatively analyzed. Plant leaf samples were collected from various localities in Samsun province and were dried. The vein patterns were analyzed by applying a clearing and staining process to dried leaves. Significant differences were determined across the leaves of the studied species in terms of characters such as leaf perimeter and area, no of nodes and edges, total network length and total network area, mean length, mean width, mean 2D and 3D surface areas and mean volume of the edges. When the clearing and staining stages are applied carefully, the morphometric properties of the vascularization may provide reliable characters that will contribute to the research in many fields such as systematic, physiology and ecology. [ABSTRACT FROM AUTHOR]

Persea psammophila, a new species of Lauraceae collected near the border between the states of Bahia, municipality of Maiquinique, and Minas Gerais, municipality of Jordânia, Brazil, is described and illustrated. The new species belongs to Persea subg. Eriodaphne. It is distinguished from other Neotropical Persea species by the treelet habit in combination with sparsely pubescent twigs, elliptic to mainly obovate leaves, adaxially glabrous, abaxially sparsely pubescent and papillose, sparsely pubescent inflorescences, pubescent, relatively small flowers, and floral parts smaller than congeneric species in the Atlantic rainforest. Its putative relationships within the genus are discussed. Illustrations and comments on micromorphological and anatomical features of leaves of this new species are provided, comparing them to those of congeners. [ABSTRACT FROM AUTHOR]

With the aim of recognizing and identifying both fertile and sterile specimens of Ocotea from the Reserva Natural Vale, Linhares, we analyzed the leaf venation pattern of 31 species, 13 of them being described and illustrated for the first time. A dichotomous identification key was built from a matrix of 12 venation characters and 36 states, which allowed to distinguish the taxa. [ABSTRACT FROM AUTHOR]

The sharpshooter Tapajosa rubromarginata (Signoret) (Hemiptera: Cicadellidae, Proconiini), a vector of the bacterium Xylella fastidiosa Wells et al. (Xanthomonadaceae) that causes citrus variegated chlorosis, has more than 30 reported host plant species. The fitness of a phytophagous insect is determined by the host plant suitability, plant resistance, and the natural enemies. The aim of this study was to: (1) identify plant species utilized as oviposition substrate by T. rubromarginata in the field; (2) establish the relationship between plants and clutch size; (3) establish the relationship among host plants, clutch size, and level of parasitism; and (4) establish variations in parasitoid composition and abundance in the various host plants. Egg masses of the sharpshooter were surveyed on plants reported as hosts, or those that were abundant in the study site. The number of eggs of the sharpshooter and emerged parasitoids were recorded for all the collected masses. We found egg masses of T. rubromarginata on 12 out of 21 plant species sampled. The size of the egg masses was greatly influenced by the type of leaf venation and to a lesser extent by the plant species. Parasitism rates were influenced by both leaf venation and host plant. Trichogrammatidae species were mostly associated with egg masses in plants with parallel‐veined leaves, whereas Mymaridae attacked masses laid in reticular‐veined leaves. The choice between a good host plant, but heavily attacked by parasitoids, and the host plants that are less suitable for nymphs but less frequently attacked by natural enemies, was a trade‐off for T. rubromarginata females to increase their fitness. We conclude that the host plant utilization by T. rubromarginata females in the field could be influenced by leaf structure and the strategy to avoid parasitism by selecting plants that were less attractive for parasitoids. [ABSTRACT FROM AUTHOR]

We analyzed vein and stomatal traits (vein density and vein volume per leaf area, stomatal density, stomatal pore length and pore index) and their relationships with other morphological traits [leaf area, leaf thickness and leaf mass per unit area (LMA)] of three co-occurring Mediterranean tree species with contrasting leaf habits [Quercus faginea Lam., Q. suber L. and Q. ilex L. subsp. ballota (Desf.) Samp.]. The results showed that leaf size, thickness and LMA varied among the species in parallel with the differences in leaf longevity. By contrast, the traits most related to water use showed inconsistent differences among the three species. Stomatal pore index was lowest in the species with intermediate leaf life span. The species with longest leaf longevity had highest vein density but minimum vein volume per area. Vein and stomatal traits also varied independently from other leaf traits within each species. The absence of association between LMA and vein volume suggests that a large LMA is the result of the accumulation of other tissues, and not necessarily veins. We concluded that in contrast with most economic leaf traits that tend to vary in parallel with leaf life span, traits related to water use varied inconsistently with leaf duration in the three species studied. Stomatal and vein traits, in addition, were not related to the maximum stomatal conductance of the different species. [ABSTRACT FROM AUTHOR]

Premise: Clearing leaves is a highly useful practice for many taxonomic, ecological, physiological, and eco‐physiological aspects of research. Using traditional methods, the procedure for clearing a leaf (referred to as diaphanization) can take several days or even weeks. In our laboratory we developed a technique, originally used for dissociating wood, that yields excellent epidermal and leaf venation preparations clearly showing the details of epidermal cells, hydathodes, trichomes, leaf margins, and leaf venation, in a maximum of three days. Methods and Results: A solution originally used to macerate wood (Franklin's solution) was used to accelerate the process of clearing leaves. Using this approach, it is possible to obtain clear images of the leaf adaxial and abaxial epidermal surfaces and leaf venation. Our technique works with both fragile and sturdy leaves, as well as with thin roots and stems. A few examples are presented. Conclusions: Franklin's solution is very simple to prepare and easy to manipulate. This new technique has the advantage of separating the leaf epidermal layers and venations, which can then be clearly observed. [ABSTRACT FROM AUTHOR]

Premise: Physiological processes may vary within leaf laminae; however, the accompanying heterogeneity in leaf venation is rarely investigated because its quantification can be time consuming. Here we introduce accelerated protocols using existing software to increase sample throughput and ask whether laminae venation varies among three crop types and four subspecies of Brassica rapa. Methods: FAA (formaldehyde, glacial acetic acid, and ethanol)‐fixed samples were stored in ethanol. Without performing any additional clearing or staining, we tested two methods of image acquisition at three locations along the proximal‐distal axis of the laminae and estimated the patterns of venation using the program phenoVein. We developed and made available an R script to handle the phenoVein output and then analyzed our data using linear mixed‐effects models. Results: Beyond fixation and storage, staining and clearing are not necessary to estimate leaf venation using phenoVein if the images are acquired using a stereomicroscope. All estimates of venation required some manual adjustment. We found a significant effect of location within the laminae for all aspects of venation. Discussion: By removing the clearing and staining steps and utilizing the semi‐automated program phenoVein, we quickly and cheaply acquired leaf venation data. Venation may be an important target for crop breeding efforts, particularly if intralaminar variation correlates with variation in physiological processes, which remains an open question. [ABSTRACT FROM AUTHOR]

Molecular phylogenetic results had shown that Tephroseris, a genus differentiated from its closest relatives by its pinnately veined leaves, also contains species with palmate leaf venation. This had led to the conclusion that leaf venation is a homoplasious character in the lineage containing Tephroseris. We here take a closer look at leaf venation in Tephroseris and other species of Asteraceae-Senecioneae. We found that leaf venation in Tephroseris is distinct from leaf venation in Jacobaea vulgaris and Senecio vulgaris, which both have pinnately veined leaves as typical for most species of their respective genera, and that description of the leaves of Tephroseris as pinnately veined is incorrect. Instead, leaf venation in Tephroseris is very similar to that of upper cauline leaves of Ligularia stenocephala, a species with clearly palmately veined basal and lower cauline leaves. Both L. stenocephala and Tephroseris are part of the Ligularia - Cremanthodium - Parasenecio (L - C - P) complex. We conclude that leaf venation in Tephroseris is best regarded as derived from palmate leaf venation found in the large majority of species in the L - C - P complex, and presents no morphological obstacle to the circumscription of the genus. [ABSTRACT FROM AUTHOR]

The purpose of this study is to identify plant species using leaf venation features. Leaf venation features were obtained through the extraction of leaf venation features. The leaf image segmentation was performed to obtain the binary image of the leaf venation which is then determined the branching point and ending point. From these points, the extraction of leaf venation feature was performed by calculating the value of straightness, a different angle, length ratio, scale projection, skeleton length, number of segments, total skeleton length, number of branching points and number of ending points. So that from the extraction of leaf venation features 19 features were obtained. Identification of plant species was carried out using Support Vector Machine (SVM) with RBF kernel. The learning model was built using 75% of the training data. The testing results using 25% of the data on the training model, obtained an accuracy of 82.67%, with an average of precision of 84% and recall of 83%. [ABSTRACT FROM AUTHOR]

Molecular phylogenetic results had shown that Tephroseris, a genus differentiated from its closest relatives by its pinnately veined leaves, also contains species with palmate leaf venation. This had led to the conclusion that leaf venation is a homoplasious character in the lineage containing Tephroseris. We here take a closer look at leaf venation in Tephroseris and other species of Asteraceae–Senecioneae. We found that leaf venation in Tephroseris is distinct from leaf venation in Jacobaea vulgaris and Senecio vulgaris, which both have pinnately veined leaves as typical for most species of their respective genera, and that description of the leaves of Tephroseris as pinnately veined is incorrect. Instead, leaf venation in Tephroseris is very similar to that of upper cauline leaves of Ligularia stenocephala, a species with clearly palmately veined basal and lower cauline leaves. Both L. stenocephala and Tephroseris are part of the Ligularia–Cremanthodium–Parasenecio (L–C–P) complex. We conclude that leaf venation in Tephroseris is best regarded as derived from palmate leaf venation found in the large majority of species in the L–C–P complex, and presents no morphological obstacle to the circumscription of the genus. Citation: Kadereit J. W. & Bohley K. 2020: A note on leaf venation and the circumscription of Tephroseris (Asteraceae–Senecioneae). – Willdenowia 50: 113–117. https://doi.org/10.3372/wi.50.50111 Version of record first published online on 23 March 2020 ahead of inclusion in April 2020 issue. [ABSTRACT FROM AUTHOR]

As a member of the CLAVATA3 (CLV3)/EMBRYO SURROUNDING REGION-related (CLE) peptide family, tracheary element differentiation inhibitory factor (TDIF) plays crucial roles in vascular meristem maintenance by promoting cell proliferation and inhibiting xylem cell differentiation. In Populus trichocarpa , six TDIF-encoding genes are all expressed in vascular tissues, and in Arabidopsis PtTDIFpro:GUS lines, the expression driven by PtTDIF promoters were predominantly detected in stem vascular bundles, initiating leaves and leaf veins. Although exogenous application of two poplar TDIF peptides did not evidently affect the shoot growth in vitro , overexpression of PtTDIF genes in hybrid poplar severely retarded the internodal elongation by upregulating the expression of GA2ox and GA20ox genes and thus decreasing the level of endogenous gibberellins (GAs), which phenotypic defect could be rescued by exogenously applied GA3. In addition, TDIF overexpression unexpectedly induced a more complex venation pattern in poplar leaves, which was underpinned by the elevated expression of WOX4 and WOX13 genes. Upon TDIF treatment, the DR5:GUS poplar leaves revealed a higher GUS activity and in TDIF -overexpressing leaves, the transcript abundances of several PIN-FORMED (PIN) genes, especially that of PIN1 , were increased, which implied an integration of TDIF and auxin in mediating this process. Collectively, data of this work presented novel activities of TDIF involved in internode elongation and leaf vein formation, thus revealing the divergent functions of TDIF in perennial tree species from those in annual herbaceous Arabidopsis. [ABSTRACT FROM AUTHOR]

Premise: The proportion of woody dicots with toothed leaves increases toward colder regions, a relationship used to reconstruct past mean annual temperatures. Recent hypotheses explaining this relationship are that (1) leaves in colder regions are thinner, requiring thick veins for support and water supply, with the resulting craspedodromous venation leading to marginal teeth (support–supply hypothesis) or that (2) teeth are associated with the packing of leaf primordia in winter buds (bud‐packing hypothesis). Methods: We addressed these hypotheses by examining leaf thickness, number of primordia in buds, growing season length (mean annual temperature, MAT), and other traits in 151 deciduous woody species using georeferenced occurrences and a Bayesian model controlling for phylogeny. We excluded evergreen species because longer leaf life spans correlate with higher leaf mass per area, precluding the detection of independent effects of leaf thickness on leaf‐margin type. Results: The best model predicted toothed leaves with 94% accuracy, with growing season length the strongest predictor. Neither leaf thickness nor number of leaves preformed in buds significantly influenced margin type, rejecting the support–supply and bud‐packing hypotheses. Conclusions: A direct selective benefit of leaf teeth via a carbon gain early in the spring as proposed by Royer and Wilf (2006) would match the strong correlation between toothed species occurrence and short growing season found here using Bayesian hierarchical models. Efforts should be directed to physiological work quantifying seasonal photosynthate production in toothed and nontoothed leaves. [ABSTRACT FROM AUTHOR]

Premise of research. Although the Nymphaeaceae are an ancient angiosperm family, fossil leaves with nymphaeacean affinities from the Paleogene have nearly always been assigned to modern genera. Yet during the diversification of this group, it is extremely likely that transitional forms in this family evolved since its origin over 100 million years ago and should show up in the fossil record. Here, we describe an extinct genus of nymphaeacean leaf with transitional characters from the Eocene Lake Messel locality, which is, according to phylogenetic analysis, a member of the main Nymphaeaceae clade excluding Nuphar. Methodology. Over 39 fossil leaves from the Messel Pit near Darmstadt, Germany, were studied, coded for 40 of 55 morphological and leaf architecture characters, and analyzed phylogenetically. Analyses were run with PAUP* of the Messel leaf morphotype combined with living taxa and then together with previously described fossil Nymphaeales. Pivotal results. Inclusion of the Messel leaf with living taxa results in three trees with similar topology except for the relationship within Nuphar. Bootstrap data strongly support inclusion of the Messel leaf in the order Nymphaeales and the family Nymphaeaceae. In analyses with only living taxa, the Messel leaf places beyond Nuphar within the remaining Nymphaeaceae. In analyses with living and other fossil taxa, it places at the base of the Nuphar clade. Based on its suite of characters, the Messel leaf is recognized here as an intermediate between existing genera and described as a new extinct genus and species. Conclusions. The Eocene water lily from Messel is described here as a new genus and species, Nuphaea engelhardtii Gee and David W. Taylor gen. et sp. nov., and is represented by leaves with characters that are transitional to those of modern Nuphar , Nymphaea , and other Nymphaeaceae. This study offers new evidence of greater biodiversity in Nymphaeaceae in the Cenozoic. [ABSTRACT FROM AUTHOR]

This paper presents a novel approach to classify the leaf shape and to identify plant species using venation detection. The proposed approach consists of five main steps to extract the leaf venation, including canny edge detection, remove leaf boundary, extract curve, and produce hue normalization image and image fusion. Moreover, to localize the edge direction efficiently, the lines that extracted from pre-processing are further divided into smaller segments. Thirty-two leaf images of Malaysian plants are analysed and evaluated with two different datasets, Flavia and Acer. The average accuracy is obtained by 98.6 and 89.83% for Flavia and Acer datasets, respectively. Experimental results show the effectiveness of the proposed approach for shape recognition with high accuracy. [ABSTRACT FROM AUTHOR]

In this contribution, the diversity of functional leaf architecture and its association with climate is studied for extant woody dicot species of North America and Europe/South West Asia. The results are compared to fossil leaves of seventeen locations in Central Europe ranging from the Paleogene to Neogene. Four functional leaf traits, lobation, margin, type of primary and secondary venation, were selected as defining sixteen basic functional architectures (Trait Combination Types, TCT). Diversity of leaf architecture was studied as Shannon diversity (meaning frequency and evenness of TCT occurrence) as realized by site-specific species composition. The extant data indicate significant positive correlations of Shannon diversity of leaf architecture with temperature particularly for North America. After having reached a peak at about 18 °C MAT, functional diversity of leaf architecture then declines in North America with rising MAT. This decline occurs mostly for drier sites, probably because humidity becomes more influential at higher MAT, with low water availability driving selective pressure towards adaptive convergence. The data indicate that warm environments are able to accommodate a higher variety of leaf types than colder environments, unless water supply is scarce. The fossil data essentially agree with the recent data, with the exception of sites harbouring fossil leaves preserved in marine sediments. Here, the diversity of leaf architecture is lower which is probably due to taphonomic bias. Highest leaf architecture diversity was found for the Pliocene sites, although no distinct relationship with stratigraphic age could be identified. The results of this study indicate that diversity of leaf architecture may be a useful source of information for palaeoecology and palaeoclimate and merits further study. • Leaf diversity-climate relationship is studied for North America and Europe-South West Asia. • Functional leaf diversity increases with mean annual temperature. • Humidity modulates leaf diversity in warmer climates. • Fossil leaf diversity are mostly consistent with these results. • Leaf diversity is suggested as a relevant source of information for palaeoclimate. [ABSTRACT FROM AUTHOR]

Premise of the Study: Studies across diverse species have established theory for the contribution of leaf traits to plant drought tolerance. For example, species in more arid climates tend to have smaller leaves of higher vein density, higher leaf mass per area, and more negative osmotic potential at turgor loss point (πTLP). However, few studies have tested these associations for species within a given lineage that have diversified across an aridity gradient. Methods: We analyzed the anatomy and physiology of 10 Ceanothus (Rhamnaceae) species grown in a common garden for variation between and within "wet" and "dry" subgenera (Ceanothus and Cerastes, respectively) and analyzed a database for 35 species for leaf size and leaf mass per area (LMA). We used a phylogenetic generalized least squares approach to test hypothesized relationships among traits, and of traits with climatic aridity in the native range. We also tested for allometric relationships among anatomical traits. Key Results: Leaf form, anatomy, and drought tolerance varied strongly among species within and between subgenera. Cerastes species had specialized anatomy including hypodermis and encrypted stomata that may confer superior water storage and retention. The osmotic potentials at turgor loss point (πTLP) and full turgor (πo) showed evolutionary correlations with the aridity index (AI) and precipitation of the 10 species' native distributions, and LMA with potential evapotranspiration for the 35 species in the larger database. We found an allometric correlation between upper and lower epidermal cell wall thicknesses, but other anatomical traits diversified independently. Conclusions: Leaf traits and drought tolerance evolved within and across lineages of Ceanothus consistently with climatic distributions. The πTLP has signal to indicate the evolution of drought tolerance within small clades. [ABSTRACT FROM AUTHOR]

* Background and Aims The structural properties of leaf venation and xylem anatomy strongly influence leaf hydraulics, including the ability of leaves to maintain hydraulic function during drought. Here we examined the strength of the links between different leaf venation traits and leaf hydraulic vulnerability to drought (expressed as P50leaf by rehydration kinetics) in a diverse group of 26 woody angiosperm species, representing a wide range of leaf vulnerabilities, from four low-nutrient sites with contrasting rainfall across eastern Australia. v Methods For each species we measured key aspects of leaf venation design, xylem anatomy and leaf morphology. We also assessed for the first time the scaling relationships between hydraulically weighted vessel wall thickness (th) and lumen breadth (bh) across vein orders and habitats. * Key Results Across species, variation in P50leaf was strongly correlated with the ratio of vessel wall thickness (th) to lumen breadth (bh) [(t/b)h; an index of conduit reinforcement] at each leaf vein order. Concomitantly, the scaling relationship between th and bh was similar across vein orders, with a log-log slope less than 1 indicating greater xylem reinforcement in smaller vessels. In contrast, P50leaf was not related to th and bh individually, to major vein density (Dvmajor) or to leaf size. Principal components analysis revealed two largely orthogonal trait groupings linked to variation in leaf size and drought tolerance. * Conclusions Our results indicate that xylem conduit reinforcement occurs throughout leaf venation, and remains closely linked to leaf drought tolerance irrespective of leaf size. [ABSTRACT FROM AUTHOR]

Abstract: Nature offers structural solutions to various optimization problems. For example, an optimal, low‐shedding water transport at various scales is achieved with quasi‐fractal structures, shown to be close to optimal. In a series of projects, metallic network analogs of some of these solutions to make high‐efficiency transparent conductors are studied. Specifically, transparent conductors are developed by directly metalizing leaf venations, spider webs, and other organic fibers. Also, the natural process of self‐cracking, similar to that occurring in the mud of dried‐out riverbeds, is employed to develop masks for metallic network fabrications. These comprehensive studies and developments contributed to, and in some cases initiate new directions in the field of network transparent conductors. These structures offer performance exceeding those of conventional oxide‐based films, while providing a possibility of reduced processing expense. This paper provides a concise, comparative review of this study and other groups' efforts in recent years. In the context of applications, the performance criteria are defined, and with those as a guideline, practicality of the most promising networks is discussed. [ABSTRACT FROM AUTHOR]

We undertook a comparative study of the leaf venation characteristics of Dioscorea species from all seven sections distributed in China (33 species, 1 subspecies and 3 varieties). We established that leaf venation has a taxonomic significance in Dioscorea. The sections Combili, Opsophyton Lasiophyton and Shannicorea all show consistent acrodromous venation (a subtype of palmate venation), with Botryosicyos exhibiting consistent pinnate venation. However, sections Stenophora and Enantiophyllum show obvious intrasectional differences. For example, D. simulans and D. biformifolia of section Stenophora have acrodromously veined middle leaflets, whereas the side leaflets are pinnately veined; D. cirrhosa and D. cirrhosa var. cylindrica of section Enantiophyllum show dichotomous veinlets. Other species in the same section show either one-branched veinlets or multiple branched veinlets. In addition to the discrepancy in venation patterns, differences in many other important morphological characteristics and chemical components were also observed. Therefore, D. simulans and D. biformifolia can be reasonably excluded from section Stenophora, and section Illigerestrum can be rebuilt using these two species. In addition, D. cirrhosa and D. cirrhosa var. cylindrica should be removed from section Enantiophyllum and placed into another new section. D. simulans and D. biformifolia show pinnate venation, and the complexity of their leaf organization (with both simple and compound leaves) also points to variations between the pinnate and acrodromous veins in Dioscorea. The repeated presence of palmate and pinnate venation in multiple angiosperm clades also suggests that the formation and evolution of venation are likely the result of evolutionary adaptation to ecological environments. [ABSTRACT FROM AUTHOR]

Growth of the tocopherol-deficient vte1 mutant and Col-0 wild type of Arabidopsis thaliana in a sunlit glasshouse revealed both similarities and differences between genotypes. Photosynthetic capacity and leaf mesophyll features did not differ between mutant and wild type. Likewise, the total volume of water conduits (tracheary elements, TEs), sugar conduits (sieve elements, SEs), and sugar-loading cells (companion and phloem parenchyma cells) on a leaf area basis were unaffected by tocopherol deficiency. However, tocopherol deficiency yielded smaller and more numerous minor veins with fewer phloem cells and smaller TEs, resulting in greater ratios of TEs to SEs. The smaller TEs in the vte1 mutant may present a decreased risk for cavitation under high evaporative demand or in response to freezing. In turn, compensation for fewer phloem cells and smaller TEs by more numerous veins may bolster resistance to cavitation at no cost to photosynthetic capacity. [ABSTRACT FROM AUTHOR]

A comparative study of leaf anatomy was conducted on some Ficus taxa namely as F. binnendykii var. coriacea, F. beccarii, F. kerkhovenii, F. sinuata, F. crassiramea and F. parietalis. The objective of this study is to determine the taxonomic value of leaf anatomical characteristics in selected Ficus taxa. Methods employed include transverse section of leaf lamina and margin using sliding microtome. The presence of continuous sclerenchyma cells surrounding vascular bundles in the leaf lamina, cystolith cells and swollen tracheids in leaf venation are common characteristics shared by all taxa studied. Taxa studied can be distinguished by the shape of marginal outline, presence and types of trichomes, types of lamina venation, presence of secretory cells, solitary crystal, druses, hypodermis and the layers of palisade cells underneath the adaxial epidermis and also in the present of cuticle. Some characters, such as the presence of collenchyma cells underneath the adaxial epidermis and above the palisade cells of primary vascular bundles in the leaf lamina in F. sinuata, complex veinlets of leaf venation in F. kerkhovenii, cystolith trichomes in F. beccarii and presence of short-stalked capitate (bicellular terminal) trichomes in F. parietalis are unique to certain species and are therefore useful as diagnostic characters. This study showed that anatomical characteristics of leaf lamina have taxonomic significance that can be used in differentiation and identification in Ficus taxa studied. [ABSTRACT FROM AUTHOR]

A study on the variation of leaf venation pattern was undertaken on 43 taxa belonging to 19 genera of Sapindaceae in Malaysia. Results showed that there were 17 venation patterns observed based on the leaf lamina venation, ultimate marginal and veinlet patterns. A total of 15 taxa showed bi-veinlets, 15 taxa uni-veinlets, eight taxa simple veinlets, three taxa triveinlet patterns and two other taxa with no ending veinlets. The presence of idioblast cells on the leaf lamina surfaces, presence and localization of simple trichomes on the leaf veins or on the leaf epidermis are the diagnostic characteristics that can be used in identification of Guioa, Harpullia and Glenneia. Druses observed on the leaves lamina can be very useful for species identification of Filicium decipiens (Wight & Arn.) Thwaites. Combination of variation in the leaf venation and diagnostic characteristics found in this study have taxonomic value especially in species and genus identification and differentiation in Sapindaceae in Malaysia. [ABSTRACT FROM AUTHOR]

Background: The analysis of complex networks both in general and in particular as pertaining to real biological systems has been the focus of intense scientific attention in the past and present. In this paper we introduce two tools that provide fast and efficient means for the processing and quantification of biological networks like Drosophila tracheoles or leaf venation patterns: the Network Extraction Tool (NET) to extract data and the Graph-edit-GUI (GeGUI) to visualize and modify networks. Results: NET is especially designed for high-throughput semi-automated analysis of biological datasets containing digital images of networks. The framework starts with the segmentation of the image and then proceeds to vectorization using methodologies from optical character recognition. After a series of steps to clean and improve the quality of the extracted data the framework produces a graph in which the network is represented only by its nodes and neighborhood-relations. The final output contains information about the adjacency matrix of the graph, the width of the edges and the positions of the nodes in space. NET also provides tools for statistical analysis of the network properties, such as the number of nodes or total network length. Other, more complex metrics can be calculated by importing the vectorized network to specialized network analysis packages. GeGUI is designed to facilitate manual correction of non-planar networks as these may contain artifacts or spurious junctions due to branches crossing each other. It is tailored for but not limited to the processing of networks from microscopy images of Drosophila tracheoles. Conclusion: The networks extracted by NET closely approximate the network depicted in the original image. NET is fast, yields reproducible results and is able to capture the full geometry of the network, including curved branches. Additionally GeGUI allows easy handling and visualization of the networks. [ABSTRACT FROM AUTHOR]

Background: Global Plants, a collaborative between JSTOR and some 300 herbaria, now contains about 2.48 million high-resolution images of plant specimens, a number that continues to grow, and collections that are digitizing their specimens at high resolution are allocating considerable recourses to the maintenance of computer hardware (e.g., servers) and to acquiring digital storage space. We here apply machine learning, specifically the training of a Support-Vector-Machine, to classify specimen images into categories, ideally at the species level, using the 26 most common tree species in Germany as a test case. Results: We designed an analysis pipeline and classification system consisting of segmentation, normalization, feature extraction, and classification steps and evaluated the system in two test sets, one with 26 species, the other with 17, in each case using 10 images per species of plants collected between 1820 and 1995, which simulates the empirical situation that most named species are represented in herbaria and databases, such as JSTOR, by few specimens. We achieved 73.21% accuracy of species assignments in the larger test set, and 84.88% in the smaller test set. Conclusions: The results of this first application of a computer vision algorithm trained on images of herbarium specimens shows that despite the problem of overlapping leaves, leaf-architectural features can be used to categorize specimens to species with good accuracy. Computer vision is poised to play a significant role in future rapid identification at least for frequently collected genera or species in the European flora. [ABSTRACT FROM AUTHOR]

A fundamental goal in ecology is to link variation in species function to performance, but functional trait-performance investigations have had mixed success. This indicates that less commonly measured functional traits may more clearly elucidate trait-performance relationships. Despite the potential importance of leaf vein traits, which are expected to be related to resource delivery rates and photosynthetic capacity, there are few studies, which examine associations between these traits and demographic performance in communities. Here, we examined the associations between species traits including leaf venation traits and demographic rates (Relative Growth Rate, RGR and mortality) as well as the spatial distributions of traits along soil environment for 54 co-occurring species in a subtropical forest. Size-related changes in demographic rates were estimated using a hierarchical Bayesian approach. Next, Kendall's rank correlations were quantified between traits and estimated demographic rates at a given size and between traits and species-average soil environment. Species with denser venation, smaller areoles, less succulent, or thinner leaves showed higher RGR for a wide range of size classes. Species with leaves of denser veins, larger area, cheaper construction costs or thinner, or low-density wood were associated with high mortality rates only in small size classes. Lastly, contrary to our expectations, acquisitive traits were not related to resource-rich edaphic conditions. This study shows that leaf vein traits are weakly, but significantly related to tree demographic performance together with other species traits. Because leaf traits associated with an acquisitive strategy such as denser venation, less succulence, and thinner leaves showed higher growth rate, but similar leaf traits were not associated with mortality, different pathways may shape species growth and survival. This study suggests that we are still not measuring some of key traits related to resource-use strategies, which dictate the demography and distributions of species. [ABSTRACT FROM AUTHOR]

The Plant Research Laboratory at The New York Botanical Garden maintains a variety of research samples for biodiversity studies. The collections are the products of botanical exploration, laboratory research, collaborations, and donations from the scientific community. These collections are enumerated, and information about herbarium voucher specimens, the history of the collections, and their current use is provided. [ABSTRACT FROM AUTHOR]

Understanding the extremely variable, complex shape and venation characters of angiosperm leaves is one of the most challenging problems in botany. Machine learning offers opportunities to analyze large numbers of specimens, to discover novel leaf features of angiosperm clades that may have phylogenetic significance, and to use those characters to classify unknowns. Previous computer vision approaches have primarily focused on leaf identification at the species level. It remains an open question whether learning and classification are possible among major evolutionary groups such as families and orders, which usually contain hundreds to thousands of species each and exhibit many times the foliar variation of individual species. Here, we tested whether a computer vision algorithm could use a database of 7,597 leaf images from 2,001 genera to learn features of botanical families and orders, then classify novel images. The images are of cleared leaves, specimens that are chemically bleached, then stained to reveal venation. Machine learning was used to learn a codebook of visual elements representing leaf shape and venation patterns. The resulting automated system learned to classify images into families and orders with a success rate many times greater than chance. Of direct botanical interest, the responses of diagnostic features can be visualized on leaf images as heat maps, which are likely to prompt recognition and evolutionary interpretation of a wealth of novel morphological characters. With assistance from computer vision, leaves are poised to make numerous new contributions to systematic and paleobotanical studies. [ABSTRACT FROM AUTHOR]

Background and Aims The influence of leaf mechanical properties on local ecosystem processes, such as trophic transfer, decomposition and nutrient cycling, has resulted in a growing interest in including leaf mechanical resistance in large-scale databases of plant functional traits. 'Specific work to shear' and 'force to tear' are two properties commonly used to describe mechanical resistance (toughness or strength) of leaves. Two methodologies have been widely used to measure them across large datasets. This study aimed to assess correlations and standardization between the two methods, as measured by two widely used apparatuses, in order to inter-convert existing data in those global datasets. Methods Specific work to shear (WSS) and force to tear (FT) were measured in leaves of 72 species from southeastern Australia. The measurements were made including and excluding midribs. Relationships between the variables were tested by Spearman correlations and ordinary least square regressions. Key Results A positive and significant correlation was found between the methods, but coefficients varied according to the inclusion or exclusion of the midrib in the measurements. Equations for prediction varied according to leaf venation pattern. A positive and significant (r=0.90, P<0.0001) correlation was also found between WSS values for fresh and rehydrated leaves, which is considered to be of practical relevance. Conclusions In the context of broad-scale ecological hypotheses and used within the constraints recommended here, leaf mechanical resistance data obtained with both methodologies could be pooled together into a single coarser variable, using the equations provided in this paper. However, more detailed datasets of FT cannot be safely filled inwith estimations based on WSS, or vice versa. In addition, WSS values of green leaves can be predicted with good accuracy from WSS of rehydrated leaves of the same species. [ABSTRACT FROM AUTHOR]

Leaf venation of 28 species and 2 variety species of Berberis (Berberidaceae) in Guizhou were made a comparative observation to search new taxonomic evidences and make a study of its systematic significance in Berberis by the means of making leaf venation specimens and clearing leaf specimens. The results showed that venation pattern could be divided into five types: semicraspedodromous, festooned semicraspedodromous, simple brochidodromous, festooned brochidodromous and the mixed. The highest vein order is fifth-order course. Primary veins framework were all pinnate and had a single fint-order vein, the size included massive, stout, moderate and weak four types and the branching ways include monopodial and sympodial. Major secondary vein framework include two types: one type was that major secondaries branch to the margin, one of the branches terminates at the margin, and the others joined the superjacent major secondary or formed more than one set of loops; the other was that major secondaries joined in a series of prominent arches and loops of secondary gauge or branched into multiple sets of loops of secondary gauge, often with accessory loops of higher gauge and all the major secondaries did not reach the margin, variation of major secondaries angle to midvein separately. Interior secondaries present or absent, formed loops of secondary gauge or branched to the base of the leaf and midvein if present; minor secondary course included semicraspedodromous, simple brochidodromous and eucamptodromous; intersecondary veins were complicated, but the average number of in-tersecondry veins per intercostal area were different among the species. Tertiary veins crossed between adjacent secondaries , anastomose with other tertiary veins and secondary veins to form a net or branch without forming a tertiary reticulum. Quaternary and quinternary veins were formed by fourth-order vein and fifth-order vein courses, and always mixed, they anastomosed with other veins to form a net or branch freely and to be the fines vein-order the leaf exhibits, besides, they were also components of freely ending veinlets. The present of the areolation was from poor development to good development. Freely ending veinlets changed from unbranched to branch unequal. Marginal ultimate venations included the absent, incomplete, spiked and looped. Mott species had leaf teeth along the margin, number of teeth per centimeter and gland characters in the tooth are different among the species, and had identifica- tion values, but other tooth characters such as tooth spacing and shape were complicated and changeful or had little differences among the species, at the same time, venation in the teeth were unstable, too. Besides, leaf teeth had an effett on the leaf venation pattern. Different kinds of leaf venation patterns presented among the species and had a important significance in taxonomy, variations of leaf venation patterns and complicated degrees showed the evolvement characters of the Berberis ; present of the leaf teeth and its characters also had certain significance in taxonomy and systematology. Main leaf venation characters of the species were summarized in a table for the species of Berberis in Guizhou, based on the leaf venation characters with main diagnostic morphologically. [ABSTRACT FROM AUTHOR]

A relationship exists between the two-dimensional shape of leaves and their venation architecture, such that broad or broad-lobed leaves can have leaf tissue far from major veins, potentially creating stronger gradients in water potential -- and associated photosynthetic function -- than found across narrow counterparts. We examined the spatial patterns of photosynthetic efficiency (ΔF/F[sub m]') and non-photochemical quenching (NPQ) in response to increased vapour pressure deficit (VPD) using two morphs of Lomatia tinctoria (Labill.) R.Br: those with broad-lobed and those with narrow-lobed leaves. Stomatal conductance (g[sub s]), instantaneous water use efficiency (WUE), stomatal and minor veins density also were measured. ΔF/F[sub m]' decreased with stress but was higher and less spatially heterogeneous across broad than narrow lobes. The strongest depression in ΔF/F[sub m]' in broad lobes was at the edges and in narrow lobes, the tips. Non-photochemical quenching was spatially more varied in broad lobes, increasing at the edges and tips. Variation in photosynthetic function could not be explained by g[sub s], WUE or minor vein density, whereas proximity to major veins appeared to mitigate water stress at the tips only for broad lobes. Our findings indicate that the relationship between venation architecture and water delivery alone can partially explain the spatial pattern of photosynthetic function. [ABSTRACT FROM AUTHOR]

A study on the variation of leaf venation patterns was conducted on 21 taxa of the genus Ficus in Peninsular Malaysia. The results showed the existence of eight leaf venation patterns based on veinlets, the ultimate marginal and areolar venation. The majority of species, such as F. annulata, F. benghalensis, F. benjamina, F. deltoidea var. angustifolia, F. deltoidea var. kunstleri, F. depressa, F. elastica, F. hispida, F. microcarpa, F. religiosa, F. tinctoria, F. ucinata and F. vasculosa, show tri-veinlets. The others exhibit the following: bi-veinlets in F. aurata and F. heteropleura; uni-veinlets in F. lepicarpa, F. schwarzii and F. superba; and simple veinlets in F. aurantiacea and F. fulva. F. sagittata presents no veinlets for areolar venation. The presence of tracheid or swollen veins at the centre of the lamina and the presence of cystolith cells and trichomes are common anatomical characteristics that could assist in group classification of the studied species. Variations in leaf venation patterns are not only valuable in identifying a taxon group, but can also be used to differentiate between species in the genus Ficus. [ABSTRACT FROM AUTHOR]

The main role of leaf venation is to supply water across the photosynthetic surface to keep stomata open and allow access to atmospheric CO2 despite evaporative demand. The optimal uniform delivery of water occurs when the distance between veins equals the depth of vein placement within the leaf away from the evaporative surface. As presented here, only angiosperms maintain this anatomical optimum across all leaf thicknesses and different habitats, including sheltered environments where this optimization need not be required. Intriguingly, basal angiosperm lineages tend to be underinvested hydraulically; uniformly high optimization is derived independently in the magnoliids, monocots and core eudicots. Gymnosperms and ferns, including available fossils, are limited by their inability to produce high vein densities. The common association of ferns with shaded humid environments may, in part, be a direct evolutionary consequence of their inability to produce hydraulically optimized leaves. Some gymnosperms do approach optimal vein placement, but only by virtue of their ability to produce thick leaves most appropriate in environments requiring water conservation. Thus, this simple anatomical metric presents an important perspective on the evolution and phylogenetic distribution of plant ecologies and further evidence that the vegetative biology of flowering plants�not just their reproductive biology�is unique. [ABSTRACT FROM AUTHOR]

A study on some leaf anatomical characteristics was undertaken on two genera in Malvaceae s.l namely Byttneria L. and Pterocymbium R. Br. The objective was to determine the taxonomic value of leaf venation characteristics especially in identification and classification of species. In the study, five species were chosen, three Byttneria species, namely B. curtisii, B. jackiana, B. maingayi, and two Pterocymbium species, namely P. tinctorium and P. tubulatum. Byttneria and Pterocymbium have been split into two subfamilies, Byttneroideae and Sterculoideae, of Malvaceae s.l respectively. Leaf clearing, staining, mounting and observation under a light microscope were techniques used for the study. Results showed that the similarities and differences in leaf venation could be useful in classification and identification of species. The common characteristics found in all species studied were the presence of entire marginal venation and closed system venation with minimum free ending veinlets in the areolar venation. The variations in the leaf venation can be used to distinguish species, which are complete ultimate marginal venation in B. curtisii and B. maingayi; curved to looped pattern and incomplete, ultimate marginal venation in B. jackiana, P. tubulatum and P. tinctorium. The presence of simple unicellular trichomes in B. jackiana and two types of trichomes (simple unicellular trichomes and multicellular glandular trichomes) and crystals alongside veinlets in P. tubulatum can also be used to further identify these two species from other species studied. Therefore, the study showed that leaf anatomical characteristics in Byttneria and Pterocymbium can be used in species identification and have taxonomic value. [ABSTRACT FROM AUTHOR]

Background and Aims The large distance between peripheral leaf regions and the petiole in large leaves is expected to cause stronger negative water potentials at the leaf apex and marginal zones compared with more central or basal leaf regions. Leaf zone-specific differences in water supply and/or gas exchange may therefore be anticipated. In this study, an investigation was made to see whether zonal differences in gas exchange regulation can be detected in large leaves. Methods The diurnal course of stomatal conductance, gs, was monitored at defined lamina zones during two consecutive vegetation periods in the liana Aristolochia macrophylla that has large leaves. Local climate and stem water potential were also monitored to include parameters involved in stomatal response. Additionally, leaf zonal vein densities were measured to assess possible trends in local hydraulic supply. Key Results It was found that the diurnal pattern of gs depends on the position within a leaf in A. macrophylla. The highest values during the early morning were shown by the apical region, with subsequent decline later in the morning and a further gradual decline towards the evening. The diurnal pattern of gs at the marginal regions was similar to that of the leaf tip but showed a time lag of about 1 h. At the leaf base, the diurnal pattern of gs was similar to that of the margins but with lower maximum gs. At the the leaf centre regions, gs tended to show quite constant moderate values during most of the day. Densities of minor veins were lower at the margin and tip compared with the centre and base. Conclusions Gas exchange regulation appears to be zone specific in A. macrophylla leaves. It is suggested that the spatial–diurnal pattern of gs expressed by A. macrophylla leaves represents a strategy to prevent leaf zonal water stress and subsequent vein embolism. [ABSTRACT FROM PUBLISHER]

To provide a comparative framework to understand the evolution of auxin regulation in vascular plants, the effect of perturbed auxin homeostasis was examined in the lycophyte Selaginella kraussiana., Polar auxin transport was measured by tracing tritiated IAA in excised shoots. Shoots were cultured in the presence of auxin efflux inhibitors and exogenous auxin, and developmental abnormalities were documented., Auxin transport in Selaginella shoots is exclusively basipetal, as in angiosperms. Perturbed auxin transport results in the loss of meristem maintenance and abnormal shoot architecture. Dichotomous root branching in Selaginella appears to be regulated by an antagonistic relationship between auxin and cytokinin., The results suggest that basipetal polar auxin transport occurred in the common ancestor of lycophytes and euphyllophytes. Although the mechanisms of auxin transport appear to be conserved across all vascular plants, distinct auxin responses govern shoot growth and development in lycophytes and euphyllophytes. [ABSTRACT FROM AUTHOR]

Leaf venation patterns vary considerably between species and between leaves within a species. A mechanism based on canalization of auxin transport has been suggested as the means by which plastic yet organized venation patterns are generated. This study assessed the plasticity of Arabidopsis thaliana leaf venation in response to ectopic ground or procambial cell divisions and auxin transport inhibition (ATI). Ectopic ground cell divisions resulted in vascular fragments between major veins, whereas ectopic procambial cell divisions resulted in additional, abnormal vessels along major veins, with more severely perturbed lines forming incomplete secondary and higher-order venation. These responses imply limited vascular plasticity in response to unscheduled cell divisions. Surprisingly, a combination of ectopic ground cell divisions and ATI resulted in massive vascular overgrowth. It is hypothesized that the vascular overproduction in auxin transport-inhibited wild-type leaves is limited by simultaneous differentiation of ground cells into mesophyll cells. Ectopic ground cell divisions may negate this effect by providing undifferentiated ground cells that respond to accumulated auxin by differentiation into vascular cells. [ABSTRACT FROM PUBLISHER]

Abstract: This paper presents a method for crowd simulation based on a biologically motivated space colonization algorithm. This algorithm was originally introduced to model leaf venation patterns and the branching architecture of trees. It operates by simulating the competition for space between growing veins or branches. Adapted to crowd modeling, the space colonization algorithm focuses on the competition for space among moving agents. Several behaviors observed in real crowds, including collision avoidance, relationship of crowd density and speed of agents, and the formation of lanes in which people follow each other, are emergent properties of the algorithm. The proposed crowd modeling method is free-of-collision, simple to implement, robust, computationally efficient, and suited to the interactive control of simulated crowds. [Copyright &y& Elsevier]