Variation In Leaf Morphology Research Articles

Esenbeckia cowanii(Rutaceae), Epitypification and Emendation

A complete description of Esenbeckia cowanii Kaastra (Rutaceae) is presented, including new details for floral morphology. The original type of this taxon included only fruiting material, thus we designate an epitype with flowers. In addition, we provide taxonomic emendation to E. cowanii, including its leaf morphology variation, details of the fruit and seed, and an update of its geographic distribution.

Leaf macro- and micro-morphological altitudinal variability of Carpinus betulus in the Hyrcanian forest (Iran)

We investigated the altitudinal variation of Carpinus betulus L. in the Hyrcanian forest using leaf macro-morphological and micro-morphological traits. We collected a total of 1600 leaves from two locations. In each location, we sampled six populations along an altitudinal gradient ranging from 100 m to 1,150 m. We found that trees in the higher elevations have smaller leaf lamina than those in the lower elevations. In contrast, leaf mass per area was high at low altitudes and increased newly at the higher ones. Stomatal dimension was negatively correlated with elevation, while stomatal density was positively correlated with elevation. We also found that two transects showed the same plasticity trend. Leaf area showed the highest plasticity, while the number of veins showed the lowest plasticity. This study shows that altitude, and related temperature and rainfall, represents an important driving force in Carpinus betulus leaf morphological variation. Moreover, our results suggest that leaf area, leaf mass per area and stomatal density could influence the species responses to different ecological conditions.

A note on baobab (Adansonia digitata L.) in Kordofan, Sudan

The isolated Sudanese baobab (Adansonia digitata L.) populations, located at the northernmost limit of the East African distributional range of the species, are regarded as important genetic resources. The morphological variation in fruits of selected baobab trees in Kordofan, Sudan, was evaluated by sampling fruits and assessing their characteristics. Furthermore, locations and stem diameter at breast height of 240 baobabs were mapped for a stand in Kordofan. Our preliminary results indicated a high diversity in fruit phenotypes. Ventricose, crescent-shaped, globose and fusiform fruit types were identified. Fruit shape varied between trees but was consistent within each individual tree. Percentage of fruit pulp varied between the different fruit types with 14, 15, 18, and 21 % recorded for ventricose, fusiform, crescent-shaped and globose fruits, respectively. Interesting was also the observation of baobab morphotypes that retained leaves during the dry season. Variation in leaf morphology could also be recognised. Measurements of baobab trees revealed a density of 0.72 individuals ha−1. Stem diameters ranged from 0.06 to 4.77 m. The size class distribution (SCD) showed an inverse J-shaped curve with a SCD slope of −0.57 which indicates a viable regenerating population. Based on the results recorded, enhancement of scientific research activities on the almost unstudied baobabs in Kordofan, Sudan is highly recommended.

Variation in leaf morphology of the invasive cat's claw creeper Dolichandra unguis-cati (Bignoniaceae)

The invasive liana cat’s claw creeper Dolichandra unguis-cati (L.) L.G. Lohmann (syn. Macfadyena unguis-cati (L.) A.H. Gentry) exhibits intraspecific variation in leaf morphology, but this is rarely noted in the published literature. The present study documents variation in leaf morphology in two forms of the species that occur in Australia (long pod and short pod). Leaf morphology is compared between the two forms and the position of the shoots (trunk and ground) at the only two sites in which they co-occur. Leaves were categorised on the basis of leaflet number and the presence or absence of tendrils. Simple leaves were produced mainly on shoots growing along the ground and were more abundant in the short-pod form. Long-pod plants were dominated by bifoliate leaves with tendrils. Cat’s claw creeper exhibits considerably wider variation in leaf morphology than recorded previously. Variations in leaf morphology may be linked to differences in the genotype, developmental stage and plastic responses of the plants. Understanding these variations may have implications for taxonomic delimitation and improved management, particularly biological control involving leaf-feeding insects.

Leaf morphological variation among paper birch (<i>Betula papyrifera</i> Marsh.) genotypes across Canada

Variations in leaf morphological characteristics have been extensively studied at both interand intraspecific levels although not explicitly on paper birch (Betula papyrifera Marsh). Paper birch populations might have considerable genotypic and leaf morphological variations that have allowed them to inhabit wide environmental gradients. In this study, we analyzed variations in leaf morphological characteristics in 23 paper birch populations collected across Canada and grown in a greenhouse. Furthermore, we examined whether the variations in leaf morphological characteristics observed were related to the climate of the population’s origin. We found significant genotypic differences in all leaf morphological characteristics (p five principal components (PC) explaining 84.74% of the total variance in the original data. PCs accumulated with specific leaf area, petiole and leaf width were positively related to latitudinal, longitudinal, and elevational gradients at the population’s origin. Unpredictably, these PCs were significantly negatively correlated to precipitation and aridity index at the origin. Thus, we analyzed if correlations within leaf morphological characteristics had supported the birch populations to acclimate and produce unpredictable relations with the environment of origin. Our results showed that the populations originated in limited precipitation (during growing season) had large leaf width and petiole size but low leaf hairs on adaxial surface. Thus, all these leaf morphological features provide a basis for the birch to reduce water loss from leaves and balance water use efficiency in reduced precipitation. Furthermore, the leaf characteristics measured may also include phenotypic plasticity of the birch as an acclimation to the environment as in the greenhouse.

White-Tailed Deer Alter Specialist and Generalist Insect Herbivory Through Plant Traits

Within a plant species, leaf traits can vary across environmental, genetic, spatial, and temporal gradients, even showing drastic differences within individuals. Herbivory can also induce variation in leaf morphology, defensive structure, and chemistry including nutritional content. Indirect effects of prior insect herbivory on later herbivores have been well documented, but the induction of trait changes after vertebrate herbivory has been little explored. Here, we examined how browsing of spicebush (Lindera benzoin L.), a dominant understory shrub in eastern mesic forests, by white-tailed deer (Odocoileus virginianus L.) altered plant quality and subsequent foliar herbivory by insects. Browsing history explained ≈ 10% of overall leaf trait variation; regenerated leaves had greater water content and specific leaf area (P = 0.009), but were lower in nitrogen and greater in carbon (P < 0.001), than leaves on unbrowsed plants. However, browsing did not shift terpene chemistry as revealed by GC-MS. In the lab, caterpillars of the specialist spicebush swallowtail (Papilio troilus L.) preferred (P = 0.02) and grew 20% faster (P = 0.02) on foliage from browsed plants; whereas total herbivory in the field, including generalist insect herbivory, was twice as high on unbrowsed plants (P = 0.016). These results suggest that the ecological impacts of deer in forest understories can have cascading impacts on arthropod communities by changing the suitability of host-plants to insect herbivores.

Preference of whitefly, Bemisia tabaci, towards black gram genotypes: Role of morphological leaf characteristics

Considering that certain morphological leaf characteristics and foliar pubescence may affect insect feeding preference on plant genotypes, the present studies were undertaken to study the variation in leaf morphology and to further evaluate the influence of leaf characteristics in imparting resistance to black gram (Vigna mungo (L.) Hepper) genotypes against Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). Evaluation of nine black gram genotypes against B. tabaci in multiple-choice test revealed that moderately resistant genotypes KU 99-20 and NDU 5-7 recorded significantly lowest whitefly population (egg, nymph and adult) as compared to the susceptible genotypes IPU 02-043, KU 7-602, KU 7-605, KU 7-618 and Mash 1-1 and highly susceptible genotypes KU 7-504 and KU 7-505. Evidence for morphological leaf characteristics was gathered using data from leaf area meter, fluorescent, electron microscopy as well as direct visual observations. Correlations between morphological leaf characteristics of black gram genotypes and the whitefly population were examined. Leaf area, lamina thickness and trichome length were significantly and positively correlated with whitefly eggs, nymphs and adults whereas trichome density and angle were negatively correlated. Thus, black gram genotypes with narrow, thin and highly pubescent leaves having short, but erect trichomes should be selected for developing black gram varieties resistant to whitefly.

Leaf morphological and genetic differentiation between Quercus rubra L. and Q. ellipsoidalis E.J. Hill populations in contrasting environments

Hybridization is considered to play an important role in speciation and evolution. Given the predicted northward tree migration in the eastern USA due to the impact of climate change, hybridization between related species is expected to become more frequent due to overlapping distribution ranges in the future. Oak species are “hot spots” of contemporary hybridization, serving as model organisms in the development of ecological species concepts. Q. rubra L. and Q. ellipsoidalis E.J. Hill were selected as study species, since they show different ecological requirements but hybridize with each other where both species co-occur. To identify morphological species and differentiation patterns in this species pair in ten populations on the Upper Peninsula of Michigan we investigated both leaf morphological variation, and genetic variation at highly variable microsatellite markers. Cluster analyses using leaf morphological characters revealed two distinct clusters for directly measured leaf characters and three clusters when additionally leaf shape characters were considered. Two populations growing on dry and sandy sites and identified as Q. ellipsoidalis in the field and by genetic assignment analyses were differentiated from the other eight populations at leaf morphological characters. Strong and significant correlations of leaf morphological differences with genetic distances at microsatellite markers but not with geographic distances are consistent with a pattern of isolation by adaptation. Differentiation at genetic and leaf morphological characters between neighboring populations in contrasting environments suggested reproductive isolation between populations of different species, possibly as the result of divergent selection. More extensive sampling along the distribution range of both species and reciprocal transplant experiments between parental environments are necessary to better understand the role of interspecific gene flow and selection in the maintenance of species identity in red oak species (Quercus section Lobatae).

Variations in leaf morphology and DNA methylation following in vitro culture of Malus xiaojinensis

Juvenile trees of Malus xiaojinensis produce leaves with three to five lobes; however, adult trees do not. Thus, M. xiaojinensis serves as a model plant for studies on rejuvenation of woody perennials. To better understand effects of in vitro culture, number of passages, and plant growth regulators on observed somaclonal variations in leaf morphology, total levels of DNA methylation and expression of associated genes, including DRM2 and MET1, of apical shoot meristems of M. xiaojinensis, were evaluated. Following 17 passages of nodal stem segment culture and four passages of callus culture, levels of DNA methylation and expression of DRM2 and MET1 were determined, and found to decrease from the 11th passage of nodal stem segment culture or adventitious bud culture and from the first passage of callus culture. Levels of DNA methylation increased with increasing 2,4-dichlorophenoxyacetic acid concentrations, but decreased significantly with increasing 6-benzyladenine (BA) concentrations. Expression of DRM2 and MET1 in regenerated plantlets were negatively correlated with BA concentrations in the culture medium. Overall, less than 11 passages of nodal stem segment or adventitious bud culture did not contribute to incidence of somaclonal variation, even in the presence of low concentrations of BA (<0.5 mg/L) in the culture medium. Moreover, when nodal stem segment cultures were maintained for up to 17 passages, complete rejuvenation was observed. However, epigenetic changes were detected following the first passage of callus cultures.

A revision of theDombeya rigidacomplex (Malvaceae)

A revision of Dombeya subsect. Rigidae, which comprises two Malagasy species (D. linearifolia and D. rigida), is presented. The classification of these species within Dombeya is preferred to an alternate placement within Helmiopsis. Three subspecies of D. rigida are recognized: subsp. parvifolia, characterized by small leaves, is newly described, and subsp. guazumifolia is newly recognized at that rank. Arènes' two subspecies of D. linearifolia are synonymized, and a new subsp. muricata, characterized by fruit similar to that of D. rigida, is described. Both species display considerable variation in leaf and fruit morphology in the north, but variation is discontinuous, indicating that the species are usually reproductively isolated.

Leaf Morphology, Taxonomy and Geometric Morphometrics: A Simplified Protocol for Beginners

Taxonomy relies greatly on morphology to discriminate groups. Computerized geometric morphometric methods for quantitative shape analysis measure, test and visualize differences in form in a highly effective, reproducible, accurate and statistically powerful way. Plant leaves are commonly used in taxonomic analyses and are particularly suitable to landmark based geometric morphometrics. However, botanists do not yet seem to have taken advantage of this set of methods in their studies as much as zoologists have done. Using free software and an example dataset from two geographical populations of sessile oak leaves, we describe in detailed but simple terms how to: a) compute size and shape variables using Procrustes methods; b) test measurement error and the main levels of variation (population and trees) using a hierachical design; c) estimate the accuracy of group discrimination; d) repeat this estimate after controlling for the effect of size differences on shape (i.e., allometry). Measurement error was completely negligible; individual variation in leaf morphology was large and differences between trees were generally bigger than within trees; differences between the two geographic populations were small in both size and shape; despite a weak allometric trend, controlling for the effect of size on shape slighly increased discrimination accuracy. Procrustes based methods for the analysis of landmarks were highly efficient in measuring the hierarchical structure of differences in leaves and in revealing very small-scale variation. In taxonomy and many other fields of botany and biology, the application of geometric morphometrics contributes to increase scientific rigour in the description of important aspects of the phenotypic dimension of biodiversity. Easy to follow but detailed step by step example studies can promote a more extensive use of these numerical methods, as they provide an introduction to the discipline which, for many biologists, is less intimidating than the often inaccessible specialistic literature.

Whole organ, venation and epidermal cell morphological variations are correlated in the leaves of Arabidopsis mutants

Despite the large number of genes known to affect leaf shape or size, we still have a relatively poor understanding of how leaf morphology is established. For example, little is known about how cell division and cell expansion are controlled and coordinated within a growing leaf to eventually develop into a laminar organ of a definite size. To obtain a global perspective of the cellular basis of variations in leaf morphology at the organ, tissue and cell levels, we studied a collection of 111 non-allelic mutants with abnormally shaped and/or sized leaves, which broadly represent the mutational variations in Arabidopsis thaliana leaf morphology not associated with lethality. We used image-processing techniques on these mutants to quantify morphological parameters running the gamut from the palisade mesophyll and epidermal cells to the venation, whole leaf and rosette levels. We found positive correlations between epidermal cell size and leaf area, which is consistent with long-standing Avery's hypothesis that the epidermis drives leaf growth. In addition, venation parameters were positively correlated with leaf area, suggesting that leaf growth and vein patterning share some genetic controls. Positional cloning of the genes affected by the studied mutations will eventually establish functional links between genotypes, molecular functions, cellular parameters and leaf phenotypes.

Characterization and identification of leaf morphology of Populus deltoides Bartr. clones

Leaves are of fundamental importance to plants, representing their facility to generate power and are the sensing units of plants towards the environment. An attempt was made to characterize and compare the variations of leaf morphology of various Populus deltoides Bartr. clones by studying the winter buds and other leaf parameters of fully developed leaves. To achieve these objectives, forty-three exotic and indigenous clones of P. deltoides Bartr. were evaluated for different parameters. On the basis of various morphological characteristics the results reveal that each clone has a distinct color pattern of leaves. Different colors observed in these clones varied from light green through green to dark green. Two distinct lengths of the leaf apex were found, i.e., short and long; as well both acuminate and acute apex types were found. Erratic distribution of serration of leaves was also found. In this study, the morphological traits of leaves provided discriminatory grounds for separating various populations of P. deltoides Bartr. clones. Winter bud studies indicate that different clones vary considerably with regard to shape, color, shape of leaf scars and exudation.

Herbivore resistance of invasive Fallopia species and their hybrids

Hybridization has been proposed as a mechanism by which exotic plants can increase their invasiveness. By generating novel recombinants, hybridization may result in phenotypes that are better adapted to the new environment than their parental species. We experimentally assessed the resistance of five exotic Fallopia taxa, F. japonica var. japonica, F. sachalinensis and F. baldschuanica, the two hybrids F. × bohemica and F. × conollyana, and the common European plants Rumex obtusifolius and Taraxacum officinale to four native European herbivores, the slug Arion lusitanicus, the moth Noctua pronuba, the grasshopper Metrioptera roeselii and the beetle Gastrophysa viridula. Leaf area consumed and relative growth rate of the herbivores differed significantly between the Fallopia taxa and the native species, as well as among the Fallopia taxa, and was partly influenced by interspecific variation in leaf morphology and physiology. Fallopia japonica, the most abundant Fallopia taxon in Europe, showed the highest level of resistance against all herbivores tested. The level of resistance of the hybrids compared to that of their parental species varied depending on hybrid taxon and herbivore species. Genotypes of the hybrid F. × bohemica varied significantly in herbivore resistance, but no evidence was found that hybridization has generated novel recombinants that are inherently better defended against resident herbivores than their parental species, thereby increasing the hybrid's invasion success. In general, exotic Fallopia taxa showed higher levels of herbivore resistance than the two native plant species, suggesting that both parental and hybrid Fallopia taxa largely escape from herbivory in Europe.

Leaf morphological variation in beech (Fagus sylvatica L.) populations in Greece and its relation to their post-glacial origin

Diversity in leaf morphological traits was assessed in 38 Greek Fagus sylvatica populations, covering the distribution of the species in the country. The relationship between the post-glacial origin of these populations and leaf morphology was investigated. The results showed a complex and geographically continuous morphological diversity pattern, influenced mainly by traits expressing leaf size, leaf shape and petiole length. Two simultaneous trends appeared to be responsible for the existing diversity pattern. One was geographical, with leaf types resembling F. sylvatica subsp. sylvatica occurring in the western part of the distribution of beech in Greece and types resembling F. sylvatica subsp. orientalis being dominant in the eastern part. A second trend seemed to be connected with the post-glacial origin of the populations, as described by previous plastid DNA haplotype studies of the same trees. The genetic background and the possible adaptation of beech populations to different environmental conditions have resulted in a complex morphological pattern, especially in areas in which different post-glacial lineages appear to meet. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 165, 422–436.

Phylogeography and climatic niche evolution in live oaks (Quercus series Virentes) from the tropics to the temperate zone

Aim We investigated the phylogeography, geographical variation in leaf morphology, freezing tolerance and climatic niches of two widespread evergreen sister oak species (Quercus) in the series Virentes. Location South-eastern USA, Mexico and Central America. Methods Nuclear microsatellites and non-recombining nuclear and chloroplast DNA sequences were obtained from trees throughout the range of two sister lineages of live oaks, represented by Quercus virginiana in the temperate zone and Q. oleoides in the tropics. Divergence times were estimated for the two major geographical and genetic breaks. Differentiation in leaf morphology, analysed from field specimens, was compared with the molecular data. Freezing sensitivities of Q. virginiana and Q. oleoides populations were assessed in common garden experiments. Results The geographical break between Q. virginiana and Q. oleoides was associated with strong genetic differentiation of possible early Pleistocene origin and with differentiation in freezing sensitivity, climatic envelopes and leaf morphology. A second important geographical and genetic break within Q. oleoides between Costa Rica and the rest of Central America showed a mid-Pleistocene divergence time and no differentiation in leaf morphology. Population genetic differentiation was greater but genetic diversity was lower within the temperate Q. virginiana than within the tropical Q. oleoides, and genetic breaks largely corresponded to breaks in leaf morphology. Main conclusions Two major breaks, one between Mexico and the USA at the boundary of the two species, and a more recent one within Q. oleoides between Honduras and Costa Rica, implicate climatic changes as potential causes. The latter break may be associated with the formation of the Cordillera de Guanacaste, which was followed by seasonal changes in precipitation. In the former case, an ‘out of the tropics’ scenario is hypothesized, in which the acquisition of freezing tolerance in Q. virginiana permitted colonization of and expansion in the temperate zone, while differences in climatic tolerances between the species limited secondary contact. More pronounced Pleistocene changes in climate and sea level in the south-eastern USA relative to coastal Mexico and Central America may explain the greater population differentiation within temperate Q. virginiana and greater genetic diversity in tropical Q. oleoides. These patterns are predicted to hold for other taxa that span temperate and tropical zones of North and Central America.

Life history variation inArabidopsis lyrataacross its range: effects of climate, population size and herbivory

For plants with wide distributional areas, covering a wide range of ecologically distinct habitats, evolutionary divergence can lead to substantial phenotypic variation across a species’ range. These intraspecific trait differences can be very informative about the nature of the selective environment as they potentially reflect different environmental selection pressures while controlling for other species characteristics.In this study, multiple regression and structural equation models were used to examine the relative importance of environmental, ecological, population size and population density effects for variation in growth, reproduction and leaf morphology among 36 populations of the perennial plantArabidopsis lyratassp.petraeaacross its northwest European range.Substantial variation in temperature, soil nutrient levels and herbivory was observed across the species’ range. In addition, large differences in flowering percentage and individual seed production were found. Leaf morphology varied considerably, with a substantial amount of variation in specific leaf area and trichome density among populations.Structural equation modeling suggested that this species is sensitive to small population sizes, eutrophication and herbivory. Reproductive output was negatively related to herbivory. In addition population size was negatively associated with soil nutrient concentrations. Leaf morphology was shown to be mainly associated with temperature and herbivory. Lower specific leaf areas and lower trichome densities were related to colder areas and high trichomes densities were related to high levels of herbivory.These model results are consistent with the interpretation that, in addition to changing environmental effects across its range, ecological effects such as herbivory contribute to the large variation in life history and morphology of this species. The results reveal a strong negative effect of herbivory on the reproductive output of this species, not only via direct effects of herbivory on flowers and seeds, but also indirectly via a shift in life history strategy.

Contrasting leaf characteristics of trees and lianas in secondary and mature forests in southwestern China

We compared variation in sun-canopy leaf anatomy, morphology and photosynthetic rates of coexisting woody species (trees and lianas) in an 8-year-old secondary forest (SF) and mature forest (MF) in the wet season in Xishuangbanna, SW China. Variability of leaf traits of 66 species within growth-form groups in each forest was quantified using coefficients of variation (CV). For the mean values, the woody species in the SF had significantly higher leaf thickness and stomatal density, but lower nonmesophyll/mesophyll ratios than those in the MF. The average leaf area and leaf mass area (LMA) in the studied woody species did not change greatly during the successional process, but differed significantly between the growth forms, with trees having higher values than lianas. The light-saturated photosynthetic rate per unit leaf area (A a) of the woody species in the SF ranged from 11.2 to 34.5 μmol m−2 s−1, similarly to pioneer tree species from literature data in southeast Asia. The A a and photosynthetic nitrogen-use efficiency (PNUE) were significantly higher than those in the MF; whereas A a in the MF ranged between 9 to 21 μmol m−2 s−1, with similar values between lianas and trees. For all woody species in both SF and MF, there were no significant differences in the average values of the CV of all measured variables for both lianas and trees. However, considerable variation in leaf anatomy, morphology, and photosynthetic rates within both growth forms and forests existed, as well as substantial variation in leaf size and stomatal density. We concluded that the tropical woody species formed a heterogeneous functional group in terms of leaf morphology and physiology in both secondary and mature forests.

Development of SCAR Markers for Species Identification in the Genus Shorea (Dipterocarpaceae)

Abstract The development of molecular markers unambiguously distinguishing groups at different taxonomic levels has numerous forensic applications. The identification of tropical timber is of particular interest in this context. We describe the development of SCAR (Sequence Characterized Amplified Region) markers for forensic applications taking the example of two closely related species of the tropical tree family Shorea (Dipterocarpaceae). Two AFLP (Amplified Fragment Length Polymorphism) fragments have been described earlier showing strong differentiation between S. leprosula and S. parvifolia. The AFLP markers were isolated from a gel, re-amplified, cloned and sequenced. Primer sets were designed from these sequences and AFLP fragments were converted into SCAR markers. The SCAR markers and PCR-RFLP markers of the chloroplast region trnLF digested with HinfI were used to screen in total 557 samples of S. parvifolia and S. leprosula from nineteen widely separated populations in Indonesia. Complete genetic differentiation between species was observed based on the putatively nuclear SCAR marker and the PCR-RFLP of the cpDNA region. We found a good agreement between leaf morphological variation and species identification based on both marker types and no indication for interspecific hybridization.

Variability of Leaf Morphology and Stomatal Conductance in Soybean [Glycine max (L.) Merr.] Cultivars

Leaf epidermal structure is an important determinant of leaf gas exchange in soybeans [Glycine max (L.) Merr.] and can be used as an indirect criterion for the selection of gas exchange traits. The objective of this study was to assess the genetic variation of leaf morphology among soybean cultivars and to examine how U.S. and Japanese cultivars differ with respect to gas exchange. Over 70 cultivars, including U.S. and Japanese soybean, were grown in the field over 2 yr to determine stomatal density, guard cell length, and potential stomatal conductance, along with other morphological leaf traits. Among cultivars, stomatal density ranged from 148 to 334 mm−2 Large variation was found in potential stomatal conductance (gp), which was closely associated with stomatal conductance in the field for representative genotypes (r = 0.89, P &lt; 0.01). United States cultivars had larger gp values than Japanese and other Asian cultivars. This potential may give a physiological and morphological basis for the greater productivity observed in U.S. cultivars. On the other hand, PI 416937 showed lower stomatal conductance, which is consistent with the ability to conserve water. This study indicates the importance of leaf structure in determining gas exchange and suggests that these characteristics may be optimized to enhance dry matter productivity and water use.