Differences In Leaf Morphology Research Articles

Natural selection drives leaf divergence in experimental populations of Senecio lautus under natural conditions.

Leaf morphology is highly variable both within and between plant species. This study employs a combination of common garden and reciprocal transplant experiments to determine whether differences in leaf shape between Senecio lautus ecotypes has evolved as an adaptive response to divergent ecological conditions.We created a synthetic population of hybrid genotypes to segregate morphological variation between three ecotypes and performed reciprocal transplants where this hybrid population was transplanted into the three adjacent native environments. We measured nine leaf morphology traits across the experimental and natural populations at these sites.We found significant divergence in multivariate leaf morphology toward the native character in each environment, suggesting environmental conditions at each site exert selective pressure that results in a phenotypic shift toward the local phenotype of the wild populations.These associations suggest that differences in leaf morphology between S. lautus ecotypes have arisen as a result of divergent selection on leaf shape or associated traits that confer an adaptive advantage in each environment, which has led to the formation of morphologically distinct ecotypes.

Enhanced Expression of QTL qLL9/DEP1 Facilitates the Improvement of Leaf Morphology and Grain Yield in Rice.

In molecular breeding of super rice, it is essential to isolate the best quantitative trait loci (QTLs) and genes of leaf shape and explore yield potential using large germplasm collections and genetic populations. In this study, a recombinant inbred line (RIL) population was used, which was derived from a cross between the following parental lines: hybrid rice Chunyou84, that is, japonica maintainer line Chunjiang16B (CJ16); and indica restorer line Chunhui 84 (C84) with remarkable leaf morphological differences. QTLs mapping of leaf shape traits was analyzed at the heading stage under different environmental conditions in Hainan (HN) and Hangzhou (HZ). A major QTL qLL9 for leaf length was detected and its function was studied using a population derived from a single residual heterozygote (RH), which was identified in the original population. qLL9 was delimitated to a 16.17 kb region flanked by molecular markers C-1640 and C-1642, which contained three open reading frames (ORFs). We found that the candidate gene for qLL9 is allelic to DEP1 using quantitative real-time polymerase chain reaction (qRT-PCR), sequence comparison, and the clustered regularly interspaced short palindromic repeat-associated Cas9 nuclease (CRISPR/Cas9) genome editing techniques. To identify the effect of qLL9 on yield, leaf shape and grain traits were measured in near isogenic lines (NILs) NIL-qLL9CJ16 and NIL-qLL9C84, as well as a chromosome segment substitution line (CSSL) CSSL-qLL9KASA with a Kasalath introgressed segment covering qLL9 in the Wuyunjing (WYJ) 7 backgrounds. Our results showed that the flag leaf lengths of NIL-qLL9C84 and CSSL-qLL9KASA were significantly different from those of NIL-qLL9CJ16 and WYJ 7, respectively. Compared with NIL-qLL9CJ16, the spike length, grain size, and thousand-grain weight of NIL-qLL9C84 were significantly higher, resulting in a significant increase in yield of 15.08%. Exploring and pyramiding beneficial genes resembling qLL9C84 for super rice breeding could increase both the source (e.g., leaf length and leaf area) and the sink (e.g., yield traits). This study provides a foundation for future investigation of the molecular mechanisms underlying the source–sink balance and high-yield potential of rice, benefiting high-yield molecular design breeding for global food security.

Functional relationships between leaves and stem across canopy layers in two contrasting clones of Populus nigra L.

Populus nigra L. represents a model system for plant biology and has a productive interest in breeding for short rotation forestry. The growth potential and adaptive capacity of this species are well characterized, but the canopy effect is poorly investigated. We analyzed morphological and functional leaf traits across a multilayer canopy profile in two contrasting clones of this species, 58–861 and Poli, respectively from northern and southern Italy, grown in field plantation. The results revealed how the variation of leaf functional traits was structured within the canopy. The two clones showed differences in leaf morphology and water use efficiency, but organized a similar functional canopy structure along a vertical profile, related to a gradient of light radiation. An acropetal enrichment gradient of carbon stable isotope was found both in leaves and stem wood across a vertical canopy profile and a tight correlation was found between carbon stable isotopes of leaves and of the respective stem section. Such a functional relationship indicates that substrates for stem growth were sourced from leaf assimilates of the closest canopy layer. These results characterize the physiology of black poplar under micro-environmental conditions at intra-canopy scale and contribute to clarify the canopy effect in young trees.

Notes on Matthiola spathulata Conti (Brassicaceae)

Matthiola spathulata Conti (1900: 49) was described as a new species in the first monograph of the genus. Apart from the type, which was collected from Iran, no other collections of the species have ever been recorded in the literature (Chernyakovskaya 1939; Cullen 1965; Rechinger 1968; Townsend 1980; Gowler 1998). During a revision of Matthiola W.T.Aiton for the Flora of Iran and neighboring countries, the authors studied many specimens of the genus from NW Iran and southern Armenia that fit the description and type of M. spathulata. Then, in the process of taxonomic studies of this genus, we found that M. iranica Zeraatkar et al. (2016: 145) and M. odoratissima var. dentata Boissier (1867: 149) are conspecific with M. spathulata. The slight differences in leaf morphology, noted in the description of M. odoratissima var. dentata, occurs sometimes throughout most of the range of M. spathulata. Rechinger (1968: 234) considered that M. odoratissima var. dentata and M. farinosa Bunge ex Boissier (1867: 150) as conspecific and cited the type gathering of the former among the studied material of the latter, but no formal synonymy has been proposed by him. Matthiola spathulata is closely related to M. odoratissima W.T.Aiton (1812: 120) but differs in its entire leaves, longer petals, pedicels and fruits (Figs. 1 & 2 M–N; see below). The former is quite different from M. odoratissima in morphological characters and distribution patterns. Matthiola spathulata is distributed in NW Iran and southern Armenia. By contrast, M. odoratissima is mostly distributed along the Black Sea coast (Fig. 2O). Finally, M. spathulata was previously known only from one locality in Iran and is recorded herein for the first time from Armenia.

Altitudinal differentiation of Quercus robur in Bosnia and Herzegovina

Morphological variation based on eight measured and four derived traits was studied to establish whether there was significant variation between populations and to identify the influence of the altitude on morphological differentiation among 44 natural stands of common oak (Quercus robur L.) in Bosnia and Herzegovina, ranging from 82 to 860 m. The results point to significant intra- and inter-population differences. Elevation-related variation is less pronounced and determined largely by microclimatic factors. The results could provide management strategies for species reintroduction in the study area. There are no differences in leaf morphology between the different branches of individual trees. However, there are important variations between the altitudinal groups and closely linked to environmental factors in all traits. An important recommendation is to use seeds from oak with attention to their altitudinal origin.

Toward extending terrestrial laser scanning applications in forestry: a case study of broad- and needle-leaf tree classification

Tree species information is essential for forest research and management purposes, which in turn require approaches for accurate and precise classification of tree species. One such remote sensing technology, terrestrial laser scanning (TLS), has proved to be capable of characterizing detailed tree structures, such as tree stem geometry. Can TLS further differentiate between broad- and needle-leaves? If the answer is positive, TLS data can be used for classification of taxonomic tree groups by directly examining their differences in leaf morphology. An analysis was proposed to assess TLS-represented broad- and needle-leaf structures, followed by a Bayes classifier to perform the classification. Tests indicated that the proposed method can basically implement the task, with an overall accuracy of 77.78%. This study indicates a way of implementing the classification of the two major broad- and needle-leaf taxonomies measured by TLS in accordance to their literal definitions, and manifests the potential of extending TLS applications in forestry.

Comparison of growth traits between abundant and uncommon forms of a non-native vine, Dolichandra unguis-cati (Bignoniaceae) in Australia

Cat’s claw creeper vine, Dolichandra unguis-cati (L.) Lohmann (syn. Macfadyena unguis-cati (L.) Gentry) (Bignoniaceae), is a major environmental weed in Australia. Two distinct forms of this weed (‘long’ and ‘short’ pod), with differences in leaf morphology and fruit size, occur in Australia. The long pod form has only been reported in less than fifteen localities in the whole of south-east Queensland, while the short pod form is widely distributed in Queensland and New South Wales. This study sought to compare growth traits such as specific leaf area, relative growth rate, stem length, shoot/root ratio, tuber biomass and branching architecture between these forms. These traits were monitored under glasshouse conditions over a period of 18 months. Short pod exhibited higher values of relative growth rates, stem length, number of tubers and specific leaf area than long pod, but only after 10 months of plant growth. Prior to this, long and short pod did not differ significantly. Higher values for these traits have been described as characteristics of successful colonizers. Results from this study could partly explain why the short pod form is more widely distributed in Australia while long pod is confined to a few localities.

Effects of light intensity on leaf photosynthetic characteristics, chloroplast structure, and alkaloid content of Mahonia bodinieri (Gagnep.) Laferr.

The variation of light intensity has obvious effects on leaf external morphology, internal anatomy, and physiological characteristics; it even induces changes in secondary metabolite production. The effects of different irradiance levels on biomass, gas exchange parameters, and photosynthetic pigment contents in Mahonia bodinieri (Gagnep.) Laferr. were analyzed here. Combined analyses of physiology, cytology, and HPLC were used to study the differences in leaf morphology, structure, physiological characters, and alkaloid content in response to different irradiances. The results indicated that the highest foliar biomass was observed under I 50 (50 % of full sunlight) followed by I 30 (30 % of full sunlight), the highest net photosynthetic rate, stomatal conductance, transpiration rate values were observed under I 30 followed by I 50, and lower values occurred in I 10 (10 % of full sunlight) and I 100 (full sunlight). With increased light intensity, total leaf area and the contents of chlorophyll a (Chl a), chlorophyll b (Chl b), and chlorophyll (Chl a+b) per unit leaf area were clearly reduced, whereas leaf mass per area, carotenoid content, leaf thickness, thickness of palisade and spongy parenchyma, and stomatal density were all significantly increased. Electron microscopic observation revealed that the number of grana, stroma lamellae and the number of starch grains in chloroplasts were decreased, the number of plastoglobuli was increased when irradiance levels increased. The estimated total yield of alkaloids in a single plant was higher under I 30 and I 50 than under I 10 or I 100 as a result of the higher biomass of the plants. Therefore, I 30 and I 50 were not only beneficial to increase biomass, but also suitable for the synthesis and accumulation of the major secondary metabolites (alkaloids). Our findings provide valuable data for the determination and regulation of irradiance levels during artificial cultivation of M. bodinieri.

Genetic and phenotypic correlations among volume, wood specific gravity and foliar traits in white spruce (Picea glauca (Moench) Voss)

AbstractWhite spruce is highly valued by the forest products industry in North America. Through tree improvement efforts, selected genotypes can exceed wild sources by 30% in volume. Negative correlations between growth and wood specific gravity have been established, but differences in leaf morphology between high and low performing genotypes are less well understood. We sampled five trees from each of 30 families at each of two locations in a 25-year old progeny test in Minnesota. One wood core was collected from each tree to sample wood specific gravity (WSG), along with a branch collected from the upper crown to examine foliar traits. We confirmed negative correlations between stem volume and WSG, but several families combined high wood volume with only small reductions in WSG. Leaf area ratio and specific leaf area were positively, genetically correlated with volume growth but not correlated with WSG. Increased growth rates of selected genotypes may be attributed, in part, to shifts in allocation to leaves and in leaf morphology that may optimize light interception.

Clonal variability of several grapevine cultivars ( V. vinifera L.) grown in the Emilia-Romagna

Clonal selection has been performed over the past 2 decades by the University of Bologna to maintain the traditional grapevine cultivars grown in the Emilia-Romagna. Around 1980 budwood canes from several biotypes of the cvs Lambrusco di Sorbara, Lambrusco Salamino, Lambrusco Grasparossa, Lambrusco Maestri and Fortana were collected from old vineyards and used to establish a preliminary trial. The vines were tested for their virus status and compared for yield, grape quality, leaf characters and phenological phases in order to evaluate the biotype variability and clonal repeatability within each cultivar. L. Salamino, L. Grasparossa and L. Maestri showed very low degrees of genetic determination for yield and quality, while Fortana and L Sorbara exhibited quite high degrees. The results in both cases were independent on the virus status of the vines. While for cvs L. Salamino, L. Maestri and L. Grasparossa selection can be made only on the basis of virus status, good selection potentials were found with cvs L. Sorbara and Fortana. Fortana also exhibited marked differences in leaf morphology and phenological phases. Further investigations are needed to better characterize the diversity among biotypes of this variety, since the delimitation between cultivars and clones remains questionable.

Differences in light-harvesting, acclimation to growth-light environment, and leaf structural development between Swedish and Italian ecotypes of Arabidopsis thaliana.

Leaf morphological differences have an impact on light distribution within the leaf, photosynthesis, and photoprotection in Arabidopsis thaliana ecotypes from near the limits of this species' latitudinal distribution in Europe. Leaf morphology, photosynthesis, and photoprotection were characterized in two Arabidopsis ecotypes from near the limits of this species' latitudinal distribution in Europe (63°N and 42°N). The Swedish ecotype formed thicker leaves and upregulated photosynthesis more substantially than the Italian ecotype in high-light environments. Conversely, the smaller rosette formed, and lesser aboveground biomass accumulated, by the Swedish versus the Italian ecotype in low growth-light environments is consistent with a lesser shade tolerance of the Swedish ecotype. The response of the thinner leaves of the Italian ecotype to evenly spaced daily periods of higher light against a background of otherwise non-fluctuating low light was to perform the same rate of photosynthesis with less chlorophyll, rather than exhibiting greater rates of photosynthesis. In contrast, the thicker leaves of the Swedish ecotype showed elevated photosynthetic performance in response to daily supplemental higher light periods in a low-light growth environment. These findings suggest significant self-shading in the lower depths of leaves of the Swedish ecotype by the chloroplasts residing in the upper portions of the leaf, resulting in a requirement for higher incident light to trigger photosynthetic upregulation in the lower portions of its thicker leaves. Conversely, photoprotective responses in the Italian ecotype suggest that more excess light penetrated into the lower depths of this ecotype's leaves. It is speculated that light absorption and the degree of utilization of this absorbed light inform cellular signaling networks that orchestrate leaf structural development, which, in turn, affects light distribution and the level of absorbed versus photosynthetically utilized light in a leaf.

Insights into the differences in leaf functional traits of heterophyllous Syringa oblata under different light intensities

Many plants exhibit heterophylly; the spatially and temporally remarkable ontogenetic differences in leaf morphology may play an adaptative role in their success under diverse habitats. Thus, this study aimed to gain insights into differences in leaf functional traits of heterophyllous Syringa oblata Lindl., which has been widely used as an ornamental tree around the world under different light intensities in East China. No significant differences existed in specific leaf area (SLA) between lanceolate- and heart-shaped leaves. Differences in the investment per unit of light capture surface area deployed between lanceolate- and heart-shaped leaves may be not obvious. This may be attributing to the fact that single leaf wet and dry weight of heart-shaped leaves were significantly higher than those of lanceolate leaves but leaf length and leaf thickness of heart-shaped leaves were significantly lower than those of lanceolate leaves. The SLA of shade trees was significantly higher than that of sun trees. The investment per unit of light capture surface of shade trees was lower than that of sun trees, making it possible to increase light capture and use efficiency in low-light environments. The phenotypic plasticity of most leaf functional traits of lanceolate leaves was higher than those of heart-shaped leaves because the former is the juvenile and the latter is the adult leaf shape during the process of phylogenetic development of S. oblate. The higher range of phenotypic plasticity of leaf thickness and leaf moisture for sun trees may be beneficial to obtain a more efficient control of water loss and nutrient deprivation in high-light environments, and the lower range of phenotypic plasticity of single leaf wet and dry weight, and SLA for shade trees may gain an advantage to increase resource (especially light) capture and use efficiency in low-light environments. In brief, the successfully ecological strategy of plants is to find an optimal mode for the trade-off between various functional traits to obtain more living resources and achieve more fitness advantage as much as possible in the multivariate environment.

Habitat-specific responses of leaf traits to soil water conditions in species from a novel alpine swamp meadow community.

Species originally from alpine wetland and alpine meadow communities now coexist in a novel 'alpine swamp meadow' community as a consequence of wetland drying in the eastern Tibetan Plateau. Considering the projected increase in the fluctuation of water supply from precipitation during the growing season in this area in the future, it is important to investigate the responses of the species that make up this new community to soil water availability. Using a transplant experimental design, we compared the response of leaf traits and growth to different water conditions for species grouped according to their original habitat of wetland or meadow. Twelve perennial herbaceous species, which form an alpine swamp meadow community in Maqu County in the eastern Tibetan Plateau, were used in this study and subjected to two water treatments, namely waterlogged and dry-down. Overall, significant differences in leaf production in response to soil water availability were found for these two groups, indicating strongly different effects of water availability on their growth. Furthermore, the meadow group had lower specific leaf area, leaf area and relative leaf water content, but thicker leaves than those of the wetland group, indicating significant habitat-specific differences in leaf morphology. Regarding physiological traits, the wetland group had significantly higher photosynthetic rates in inundated conditions, whereas for the meadow group the photosynthetic rate was greatest in cyclically dry conditions. Likewise, a similar pattern was observed for stomatal conductance; however, both groups achieved higher instantaneous water use efficiency during the dry-down treatment. The results of this study indicate that the composition of the alpine swamp meadow could be sensitive to changes in precipitation and might be changed substantially by future declines in water supply, as predicted by global climate change models for this region. This potential for compositional change of the community should be considered when management and conservation decisions are made.

Coordination and plasticity in leaf anatomical traits of invasive and native vine species.

• Plant invasiveness can be promoted by higher values of adaptive traits (e.g., photosynthetic capacity, biomass accumulation), greater plasticity and coordination of these traits, and by higher and positive relative influence of these functionalities on fitness, such as increasing reproductive output. However, the data set for this premise rarely includes linkages between epidermal-stomatal traits, leaf internal anatomy, and physiological performance.• Three ecological pairs of invasive vs. noninvasive (native) woody vine species of South-East Queensland, Australia were investigated for trait differences in leaf morphology and anatomy under varying light intensity. The linkages of these traits with physiological performance (e.g., water-use efficiency, photosynthesis, and leaf construction cost) and plant adaptive traits of specific leaf area, biomass, and relative growth rates were also explored.• Except for stomatal size, mean leaf anatomical traits differed significantly between the two groups. Plasticity of traits and, to a very limited extent, their phenotypic integration were higher in the invasive relative to the native species. ANOVA, ordination, and analysis of similarity suggest that for leaf morphology and anatomy, the three functional strategies contribute to the differences between the two groups in the order phenotypic plasticity > trait means > phenotypic integration.• The linkages demonstrated in the study between stomatal complex/gross anatomy and physiology are scarce in the ecological literature of plant invasiveness, but the findings suggest that leaf anatomical traits need to be considered routinely as part of weed species assessment and in the worldwide leaf economic spectrum.

Ecotypic differentiation in seed and seedling morphology and physiology among Cicuta virosa populations

There are three different Cicuta virosa habitats in Korea: Pyeongchang (PC), a fenced wet meadow with a water shortage in spring; Hoengseng (HS), a 12 year old abandoned paddy field and narrow streamlet holding shallow water throughout the year; Gunsan (GS), a 1m deep reservoir with a floating mat composed of organic matter located 2° south of HS and PC and at very low altitude. These three populations with different altitudes, climates, water regimes and nutrient availability showed differences in leaf morphology and flowering time. We compared seed and seedling morphology and tested the sensitivity of seedlings to dryness and shade and the germination responses to light and temperature to identify intraspecific variation as ecotypic differences in C. virosa populations (p≤0.05). The seed length of GS (2.04±0.03mm) was significantly shorter than that of PC (2.44±0.05mm) and HS (2.60±0.03mm). Seed weight of GS (0.83±0.01mg) was significantly lighter than that of the others (PC: 1.47±0.02mg, HS: 1.33±0.02mg). PC and HS seedlings had larger root: shoot ratio values and GS had significantly higher relative growth rate (RGR) through 8 weeks of growth. GS seedlings were more sensitive to dryness than PC and HS in leaf chlorophyll contents, specific leaf area (SLA) and RGR. The pattern of germination responses was similar among the three populations but germination rate (%) was very different. Maximum germination percentages were 63.0%, 23.9% and 96.9% in PC, HS, and GS, respectively, under 28/18°C/14h photoperiod. The nonviable seed (%) of GS (18.1±0.7%) was significantly higher than that of the others (PC: 3.1±1.6%, HS: 3.4±0.6%) in the tetrazolium tests result. Seed mass which was correlated to other plant traits (i.e., root:shoot ratio, RGR) and germination rate were the most discriminating variables in the discriminant analysis. Seed weight was negatively correlated with temperature in January and water level and germination rate was significantly related with water level and water temperature in August. Based on these results under uniform conditions, we suggest that these three C. virosa populations from different habitats are ecotypes.

A quantitative genetic basis for leaf morphology in a set of precisely defined tomato introgression lines.

Introgression lines (ILs), in which genetic material from wild tomato species is introgressed into a domesticated background, have been used extensively in tomato (Solanum lycopersicum) improvement. Here, we genotype an IL population derived from the wild desert tomato Solanum pennellii at ultrahigh density, providing the exact gene content harbored by each line. To take advantage of this information, we determine IL phenotypes for a suite of vegetative traits, ranging from leaf complexity, shape, and size to cellular traits, such as stomatal density and epidermal cell phenotypes. Elliptical Fourier descriptors on leaflet outlines provide a global analysis of highly heritable, intricate aspects of leaf morphology. We also demonstrate constraints between leaflet size and leaf complexity, pavement cell size, and stomatal density and show independent segregation of traits previously assumed to be genetically coregulated. Meta-analysis of previously measured traits in the ILs shows an unexpected relationship between leaf morphology and fruit sugar levels, which RNA-Seq data suggest may be attributable to genetically coregulated changes in fruit morphology or the impact of leaf shape on photosynthesis. Together, our results both improve upon the utility of an important genetic resource and attest to a complex, genetic basis for differences in leaf morphology between natural populations.

Molecular systematics of Indian Crotalaria (Fabaceae) based on analyses of nuclear ribosomal ITS DNA sequences

Crotalaria L. (Fabaceae) comprises approximately 700 species that are distributed in tropical and subtropical regions of the world. In India, it is the largest legume genus with 92 species. Sequences of the nuclear internal transcribed spacer from species representing all the six recognized sections of Indian Crotalaria were subjected to phylogenetic analyses. Ancestral state reconstructions were done for two morphological characters, corolla keel beak, and leaf form. Analyses reveal five major well-supported clades within a monophyletic Crotalaria. Clade 1 has members with rostrate-spirally twisted keel beaks while the remaining four clades comprise members with keel beaks rostrate-not spirally twisted. Clade 1 further bifurcates into two clades characterized by differences in leaf morphology: (1a) contains species with simple leaves belonging to section Calycinae, section Crotalaria subsection Crotalaria and subsection Bractetae and multifoliolate leaves belonging to section Crotalaria subsection Polyphyllae (1b) contains species with trifoliate leaves belonging to section Dispermae, section Crotalaria subsection Longirostres. Sub-clade iii in Clade 1a contains four species complexes, each forming a monophyletic group. Of these one comprising C. madurensis, C. subperfoliata, C. shevaroyensis, and C. longipes is endemic to a region in southern India. Each of the others contains one endemic species and one widespread species that is sympatric with the endemic one (C. hirta and C.mysorensis; C. epunctata and C. albida; C. clarkei and C. triquetra). The present study suggests that: (1) all members of section Calycinae and most members of section Crotalaria form a clade, (2) members of section Crotalaria subsection Longirostres and section Dispermae form a distinct clade, (3) twisting of the keel beak is an apomorphy within the genus, (4) there is a reversal to keel beak rostrate-not spirally twisted in C. shevaroyensis and an independent origin of a rostrate-spirally twisted keel beak in C. humilis, and (5) the trifoliolate condition is a plesiomorphy in the genus and the simple leaf condition an apomorphy; there is a single reversal to the trifoliolate condition in C. orixensis. The current morphological classification system of Indian Crotalaria species includes six sections, but these circumscriptions are not supported by the molecular data.

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).

Revised generic delimitations for Oxypolis and Ptilimnium (Apiaceae) based on leaf morphology, comparative fruit anatomy, and phylogenetic analysis of nuclear rDNA ITS and cpDNA trnQ–trnK intergenic spacer sequence data

AbstractA phylogenetic study of Oxypolis and Ptilimnium, two small genera of tribe Oenantheae (Apiaceae: subfamily Api–oideae), was carried out. Generic circumscriptions and infrageneric and infraspecific relationships were investigated through parsimony and Bayesian inference analyses of nuclear rDNA ITS and cpDNA trnQ–5’rps16 and 3’rps16–5’trnK intergenic spacer sequences. Fruit anatomical characters were also examined and used in conjunction with leaf morphology to corroborate the results of the phylogenetic analyses. Each genus as currently delimited has both compound–leaved and rachis–leaved species. Results of the phylogenetic analyses show that neither Oxypolis nor Ptilimnium is monophyletic; each genus is split into two strongly supported clades that correspond to differences in leaf morphology within the groups. Fruit anatomical characters support these splits. The fruits of compound–leaved and rachis–leaved Oxypolis species differ in the number of commissural vittae per mericarp, the branching of the vittae, and the lignification of mericarp around the seed. The fruits of compound–leaved and rachis–leaved Ptilimnium species differ in the compression of the mericarps and the development of the marginal ribs. The fruits of rachis–leaved Oxypolis and rachis–leaved Ptilimnium species also differ in the compression of the mericarps and the development of the marginal ribs. Based on analyses of molecular data and corroboration with morphological and fruit anatomical data, new circumscriptions for the genera Oxypolis and Ptilimnium are formalized. Each of the two polyphyletic genera (Oxypolis and Ptilimnium) is split, two genera (Tiedemannia and Harperella) are resurrected, and three new combinations are made.

Legume seeders of the Cape Floristic Region inhabit more fertile soils than congeneric resprouters—sometimes

In fire-prone ecosystems, plants for the most part persist via either soil-stored seed banks (seeders) or below-ground storage structures (resprouters). Given their greater allocation of resources above ground to growth and reproduction, seeders are likely to have a higher nutrient requirement than resprouters. This may result in discernable differences in habitat nutrition and leaf morphology. These differences are probably accentuated in Cape legumes given their poor adaptation to low-P soils. It was hypothesized that legume seeders occupy habitats with greater fertility and possess larger, less sclerophyllous leaves than resprouters. Site nutrition and leaf morphologies were compared between seeders and resprouters in the genera Otholobium and Psoralea. There were no differences in leaf morphology between seeders and resprouters. Seeders sites had a higher total [N], exchangeable [Ca] and [Mg], and CEC, but lower [Fe] than resprouters. Only within Otholobium, did seeder sites have a higher Bray II [P]. This genus-specific variation in available P is probably a consequence of greater variation in soil type and precipitation between seeders and resprouters. Conversely, niche construction may contribute to the differences in soil fertility between seeders and resprouters in Psoralea. Thus, our data showed a general tendency for seeders to inhabit more fertile sites than resprouters. Caution is required, however, in generalizing these results, as our data indicate a difference in factors affecting soil nutrient availability between legume genera. Changes in soil fertility post-fire may limit legume persistence beyond the early stages of succession.