Micromorphological Sculptural Diversity in Foliar Epidermis and Trichomes Features among Invasive Species.

This study examines the role of light microscopic (LM) and scanning electron microscopic (SEM) micromorphological traits of the epidermis in identifying and classifying invasive plants. SEM was conducted to increase our understanding of microscopic qualities that are not visible in light microscopy and to elucidate unclear affinities among invasive species. The study examines invasive species' morphological and anatomical characteristics from the Pothohar Plateau of Pakistan for the first time. The results showed that various micromorphological features are very useful for species' accurate identification. Adaxial and abaxial surfaces of leaves showed variations in subsidiary cells, glands, anticlinal wall patterns, stomata, and epidermal cells. Epidermal cell shapes observed were irregular, elongated, rectangular, and polygonal. Epidermal cells having maximum length were calculated in Stellaria media (126.3 µm) on adaxial side. On the abaxial surface, the minimum length was noticed in Eucalyptus camaldulensis (28.5 µm). Both glandular and nonglandular trichomes were examined, ranging from unicellular to multicellular. Most of the investigated specimens of leaves were amphistomatic, while some were hypostomatic, like Alternanthera pungens, Calotropis procera, Cannabis sativa, Lantana camara, and Thevetia peruviana. Leaf epidermal morphology contains numerous useful systematic features for accurate identifications of plant species. The micromorphological attributes under observation provide a standard criterion to the researcher for identifications of invasive flora in future morpho-taxonomic studies.

An automatic method to quantify trichomes in Arabidopsis thaliana.

Trichomes are unicellular or multicellular hair-like appendages developed on the aerial plant epidermis of most plant species that act as a protective barrier against natural hazards. For this reason, evaluating the density of trichomes is a valuable approach for elucidating plant defence responses to a continuous challenging environment. However, previous methods for trichome counting, although reliable, require the use of specialised equipment, software or previous manipulation steps of the plant tissue, which poses a complicated hurdle for many laboratories. Here, we propose a new fast, accessible and user-friendly method to quantify trichomes that overcomes all these drawbacks and makes trichome quantification a reachable option for the scientific community. Particularly, this new method is based on the use of machine learning as a reliable tool for quantifying trichomes, following an Ilastik-Fiji tandem approach directly performed on 2D images. Our method shows high reliability and efficacy on trichome quantification in Arabidopsis thaliana by comparing manual and automated results in Arabidopsis accessions with diverse trichome densities. Due to the plasticity that machine learning provides, this method also showed adaptability to other plant species, demonstrating the ability of the method to spread its scope to a greater scientific community.

Morpho-Anatomical Study And Botanical Identification of Pogostemon auricularius (L.) Hassk. (Lamiaceae).

Pogostemon Desf. includes a wide range of taxa found in subtropical and tropical areas. Few works, however, have studied microanatomical characteristics of Pogostemon species and as yet identified features of Pogostemon auricularius (L.) Hassk. Thus, in this paper, we examined the taxonomic implications of root, stem and leaf morphology for species P. auricularius collected from Quang Tri Province. Light microscopy was mainly used in our study. Qualitative characters like stem quadrangular, hirsute; leaves opposite, ovate, margin serrulate; calyx campanulate; corolla small with separate equal lobes have been found in P. auricularius. Epidermal anatomy on the aerial parts of the species like epidermal cell shape, anticlinal walls, trichomes types, stomata types and calcium oxalate crystals types were examined as well. Quantitative characters like the length and width of leaf blade and inflorescence; the size of oil droplet, stomata and calcium oxalate crystals measured provided taxonomic significance. Based on identifying morphological characteristics of P. auricularius, we aimed to contribute to the taxonomic investigation into the genus Pogostemon and give relative morphological and microanatomical features compared with other taxa.

Implications of foliar epidermal micromorphology using light and scanning electron microscopy: A useful tool in taxonomy of Korean irises.

The genus Iris L., comprising approximately 210 species, is one of the most species-rich genera in the family Iridaceae. In this study, the first comprehensive leaf micromorphological characters of Korean irises were studied using light and scanning electron microscopy. Our objective was to evaluate the foliar micromorphological characteristics (namely epidermal cells, stomata types, and guard cell size) of Korean Iris taxa in a systematic context. All the investigated Korean Iris taxa had amphistomatic or hypostomatic leaves with anomocytic stomatal complexes. Guard cell length varied among species, ranging from 24.8 µm (I. rossii) to 56.0 µm (I. domestica). Although the presence of papillae on the outer periclinal wall is not of taxonomic significance, leaf margin pattern, guard cell size, and sunken stomata type were useful for species-level identification of Korean Iris species. The occurrence of polymorphic stomatal types was reported here for the first time, and the correlation between genome size and epidermal guard cell length was discussed.

Leaf epidermal morphology of Asparagaceae of Taiwan and its systematic significance.

The current study analyzed the epidermal morphology of Asparagaceae in detail and assessed its systematic importance. At the familial level, no consistent characteristics were found, but anticlinal wall and stomata morphology provided systematic information of different tribes, especially Ophiopogoneae and Polygonateae. In Ophiopogoneae, Liriope and Ophiopogon had similar epidermis, which implying a close relationship between them, and was also supported by related studies. The leaves of Polygonateae exhibited rounded and undulate anticlinal wall. Polygonatum arisanense var. formosanum had a rounded anticlinal wall, whereas other species exhibited undulate anticlinal walls. Different epidemis of Po. arisanense var. formosanum supported the variety treatment of Po. arisanense. The intergeneric relationship was also interpreted based on the anticlinal wall and stomata. Therefore, the epidermis could provide the systematic value of Asparagaceae. The present study also revealed the linkage of stomata and habitat types, though the adaptative significance of epidermal traits needs further study. RESEARCH HIGHLIGHTS: Anticlinal wall and stomatal morphology had systematic potential on tribal or generic levels of Asparagaceae. Stomatal types of Asparagaceae might be linked to environmental factors.

Comparative Analyses of the Self-Sealing Mechanisms in Leaves of Delosperma cooperi and Delosperma ecklonis (Aizoaceae).

Within the Aizoaceae, the genus Delosperma exhibits a vast diversification colonizing various ecological niches in South-Africa and showing evolutionary adaptations to dry habitats that might include rapid self-sealing. Leaves of Delosperma react to external damage by the bending or contraction of the entire leaf until wound edges are brought into contact. A study of leaf morphology and anatomy, biomechanics of entire leaves and individual tissues and self-sealing kinematics after a ring incision under low and high relative humidity (RH) was carried out comparing the closely related species Delosperma cooperi and Delosperma ecklonis, which are indigenous to semi-arid highlands and regions with an oceanic climate, respectively. For both species, the absolute contractions of the examined leaf segments ("apex", "incision", "base") were more pronounced at low RH levels. Independent of the given RH level, the absolute contractions within the incision region of D. cooperi were significantly higher than in all other segments of this species and of D. ecklonis. The more pronounced contraction of D. cooperi leaves was linked mainly to the elastic properties of the central vascular strand, which is approximately twice as flexible as that of D. ecklonis leaves.

Comparative foliar anatomical and pollen morphological studies of Acanthaceae using light microscope and scanning electron microscope for effective microteaching in community.

In this study, foliar anatomy and pollen morphology of 10 species of Acanthaceae has been investigated using light and scanning electron microscopy. The study was aimed to highlight the role of microscopy in microteaching at community for proper characterization of plants using palyno-anatomical characters including pollen type, exine sculpturing, shape of epidermal cells, pattern of anticlinal wall, type and size of stomata, and trichome. Most of the species have polygonal cell shapes but some species have irregular, tetragonal, and pentagonal shape of epidermal cells. The largest epidermal cell length on adaxial and abaxial surface were observed in Asystasia gangetica 66.95 and 87.40 µm whereas least was observed on adaxial surface in Justicia adhatoda 36.9 µm and on abaxial surface in Barleria cristata 35.65 µm. In anatomy, species have diacytic type of stomata, whereas stomata of paracytic type observed in two species, while in A. gangetica cyclocytic type of stomata are present. Quantitively on abaxial surface, largest stomata length 29.9 µm and width 24.30 µm was noted in B. cristata. While shortest stomata length was observed in Ruellia prostrata 25.95 µm whereas minimum width of stomata was examined in Barleria acanthoides 2.05 µm. The diversity of trichomes are present in all species except in Ruellia brittoniana. Acanthaceae can be characterized by exhibiting different pollen morphology having five types of pollen shapes, prolate, spheroidal, perprolate, subprolate, and oblate spheroidal. Exine peculiarities showing variations such as reticulate, granulate, coarsely reticulate, lophoreticulate, perforate tectate, and granulate surface were examined.

Applications of scanning electron microscopy in taxonomy with special reference to family Euphorbiaceae.

The present study was carried out to identify the 20 medicinally important species of family Euphorbiaceae by the aid of scanning electron microscopy (SEM) of the foliar anatomical characteristics. Both qualitative and quantitative measurements for the anatomical characters like epidermal cells, stomata, trichomes, and subsidiary cells on both abaxial(ab) and adaxial(ad) epidermis were recorded. Remarkable variations in these anatomical features had been observed among the studied Euphorbiaceae species. Most species had epidermal cells irregular or polygonal in shape, only five species had hexagonal cells, that is, Euphorbia neriifolia L., Euphorbia prostate Aiton, Jatropha integerrima Jacq., Vernicia fordii (Hemsl.), and Euphorbia royleana Boiss. Stomata were abundant on abaxial epidermis as compared to adaxial epidermis. E. prostate Aiton, Euphorbia pulcherrima Willd. Ex Klotzsch and Phyllanthus emblica L. possessed anomocytic stomata, and Euphorbia helioscopia L., Euphorbia cotinifolia L., E. neriifolia L., and Ricinus communis L. possessed anisocytic stomata, while rest of the species had paracytic stomata. Trichomes were present in very few species including Euphorbia hirta L., E. prostate Aiton, E. pulcherrima Willd. Ex Klotzsch, and Putranjiva roxburghii Wall. Similarly, variations were also reported by quantitative features such as E. helioscopia L. can be distinguished from E. hirta on the basis of length of epidermal cells, that is, 103.4 ± 0.15 and 74.9 ± 0.55 µm, respectively. Moreover, E. pulcherrima Willd. Ex Klotzsch had trichomes with the length of 408 ± 0.55 µm and P. roxburghii Wall. had trichome with the length of 314.2 ± 1.35 µm, respectively. These findings confirmed that taxonomic utility of the anatomical traits for the identification of studied Euphorbiaceae taxa.

Rafflesia patma Blume flower organs: histology of the epidermis and vascular structures, and a search for stomata.

MAIN CONCLUSION: A histological study of Rafflesia patma revealed the simplicity of a flower's vascular tissue and epidermal features of flower organs, including their structures and pigmentation. Rafflesia is an endophytic holoparasitic plant that infects Tetrastigma. In a previous study, we characterized the shape of the strands of an endophyte (Rafflesia patma Blume) and hypothesized their distribution. In this study, we deepened our analysis by assessing parts of flower tissue sampled during anthesis, performed surface casting of the abaxial and adaxial sides of the perigone lobe to profile their surface features, and histologically characterized the perigone lobe, perigone tube, and central column base, including the anther and cupula region. The objective of these observations was to compare tissues from different organs and the distribution of cells staining positive for tannin, suberin, and lignin. Observable features in this study were vascular and epidermal tissue. We also observed reduced vascular tissue with xylem and vascular parenchyma in multiple organs. The adaxial epidermis found in the perigone lobes and tube had papillate cells, and their function might be to assist with the emission of odor through chemical evaporation. The abaxial epidermis, also found in perigone lobes and tube, had flattened cells. These, combined with the nearby flattened parenchyma cells, especially in the outermost, early perigone lobe, might provide a tougher (stiffer) outer protective barrier for the flower. The accumulation of tannin in perigone lobes might offer protection to the flower from herbivores prior to anthesis. Although a previous observation indicated the possibility of stomata on the surface of Rafflesia flowers, no stomata were found in this study.

Chemical Defoliant Promotes Leaf Abscission by Altering ROS Metabolism and Photosynthetic Efficiency in Gossypium hirsutum.

Chemical defoliation is an important part of cotton mechanical harvesting, which can effectively reduce the impurity content. Thidiazuron (TDZ) is the most used chemical defoliant on cotton. To better clarify the mechanism of TDZ promoting cotton leaf abscission, a greenhouse experiment was conducted on two cotton cultivars (CRI 12 and CRI 49) by using 100 mg L-1 TDZ at the eight-true-leaf stage. Results showed that TDZ significantly promoted the formation of leaf abscission zone and leaf abscission. Although the antioxidant enzyme activities were improved, the reactive oxygen species and malondialdehyde (MDA) contents of TDZ increased significantly compared with CK (water). The photosynthesis system was destroyed as net photosynthesis (Pn), transpiration rate (Tr), and stomatal conductance (Gs) decreased dramatically by TDZ. Furthermore, comparative RNA-seq analysis of the leaves showed that all of the photosynthetic related genes were downregulated and the oxidation-reduction process participated in leaf shedding caused by TDZ. Consequently, a hypothesis involving possible cross-talk between ROS metabolism and photosynthesis jointly regulating cotton leaf abscission is proposed. Our findings not only provide important insights into leaf shedding-associated changes induced by TDZ in cotton, but also highlight the possibility that the ROS and photosynthesis may play a critical role in the organ shedding process in other crops.

Foliar micromorphology and its role in identification of the Apocynaceae taxa.

In the present study, we evaluate the importance of foliar epidermal micromorphological characteristics of Apocyanaceae for accurate identification and classification. The species were collected from the University of Peshawar's main campus in the spring season to observe its qualitative and quantitative features. The length and width of guard cells, stomatal pore and subsidiary cells, trichomes, and crypts on both sides of the leaf were examined. Many species were observed to be hypostomatic. Plumeria rubra, Raulfia serpentine, Thevetia peruviana, Trachelospermum lucidum, Alstonia scholaris, and Catharanthus roseus demonstrated hypostomatic leaves. Nearly all the investigated species had anisocytic type of stomata only or in combination with other types of stomata on the upper and lower epidermis. Carissa carandas had anomocytic, anisocytic, and cyclocytic type of stomata on the upper epidermis, and the lower epidermis showed variations in stomatal type, such as anomocytic, stephanocytic, brachyparacytic, and hemiparacytic. Nerium oleander had no specific shape of stomata but showed stomatal crypts in which the stomata were enclosed inside many trichomes. The taxonomic key based on stomatal types, epidermal cells, stomatal index value, and statistical analysis, along with the variations in the epidermal cells, shows the link between the selected plants species, which will provide a baseline for future anatomical studies. This study highlights many undocumented micromorphological characteristics. The anatomical characteristics observed in this study will be helpful for taxonomic identification and species delimitation of the family Apocynaceae.

Significance of leaf morphoanatomical markers for the authentication of adultered drugs sold in herbal markets of district Lahore, Pakistan.

A number of herbal plants sold in herbal markets of Lahore are under adulteration threat which can pose harmful health effects to end-user. This adulteration problem of medicinal plants can be resolved by the implication of some valuable taxonomic parameter such as leaf epidermal anatomical characteristics. Hence, this research was aimed to provide viable anatomical markers in order to resolve this adulteration issue persisted in some common marketed medicinal plants of district Lahore, that is, Cinnamomum verum Presl., Cinnamomum tamala (Buuch.-Ham.) T.Nees&Eberm., Gymnema sylvestre (Retz.) R.Br.ex Sm., Sphaeranthus indicus Linn., Artemisia maritima Linn., Achillea millifolim L., Adhatoda vasica Nees, Butea monosperma (Lam.) Taub, and Morus nigra L. Overall multiple anatomical variations (epidermal cell shape, their length and width, type of stomata, length and width of guard cells along with presence or absence of trichomes) had been reported in the study that could be worthwhile for the correct identification of medicinal plants. Irregular shapes of epidermal cells were observed in Cinnamomum verum and Achillea millifolium while pentagonal and polygonal cells were found in their adultaerants, that is, Canella winterana and Adhatoda vasica, respectively. Types of stomata were also strikingly varied among genuine plant and its adulterant, for example, anisocytic stomata were observed in Artemisia maritima while in its adulterant (Artemisia absinthium) anomocytic stomata were found. Similarly, paracytic stomata were observed in Butea monosperma, whereas its adulterant plant (Averrhoa carambola) characteristically possessed anisocytic stomata. Hence, anatomical characteristics were proved to be a valuable taxonomic tool in resolving the adulteration issue of medicinal plants.

Anatomical, Phytochemical, and Histochemical Study of Juniperus rigida Needles at Different Altitudes.

Needles of Juniperus rigida are used in Chinese traditional medicine for the treatment of brucellosis, dropsy, skin disease, and rheumatoid arthritis. This is the first study that reports anatomical structures of the J. rigida needles collected at different altitudes. The most common anatomical, phytochemical, and histochemical techniques and methods are used. The results show that anatomical structures and chemical composition change significantly at different altitudes. The main anatomical characters are significant xeromorphic structures (thick epidermis, hypodermis, and cuticle), a stomatal band, a developed vascular bundle, and a marginal resin duct. The xeromorphic structures become more pronounced with increasing altitude. The phytochemical and histochemical results demonstrate that the content of the main chemical compounds (phenols and terpenoids) basically increases at a higher elevation. Histochemical analysis localizes the phenols in epidermal cells, sponge tissue, endothelial layer cells, and stomatal bands, and the terpenoids in palisade tissue, sponge tissue, and the edge of the resin duct. This work reveals the relation between anatomy and chemistry in J. rigida needles, contributes to the quality control of its ethno-medicine, and provides the evidence to develop the commercial cultivation.

Image Analysis: Basic Procedures for Description of Plant Structures.

This chapter gives examples of basic procedures of quantification of plant structures with use of image analysis, which are commonly employed to describe differences among experimental treatments or phenotypes of plant material. Tasks are demonstrated with the use of ImageJ, a widely used public domain Java image processing program. Principles of sampling design based on systematic uniform random sampling for quantitative studies of anatomical parameters are given to obtain their unbiased estimations and simplified "rules of thumb" are presented. The basic procedures mentioned in the text are: (1) sampling, (2) calibration, (3) manual length measurement, (4) leaf surface area measurement, (5) estimation of particle density demonstrated on an example of stomatal density, and (6) analysis of epidermal cell shape.

Taxonomic significance of foliar epidermal morphology in Lamiaceae from Pakistan.

Foliar micromorphological features are useful to elucidate the taxonomy and systematics of the Lamiaceae species. Leaf epidermal morphology using scanning electron microscopy and light microscopy of 22 Lamiaceae species from 15 genera have been investigated with an aim to solve its taxonomic problem in the correct identification. Various foliar micromorphological features were observed to explain their importance in resolving the correct identification of Lamiaceae taxa. Two main types of trichomes were observed; glandular trichomes (GTs) and nonglandular trichomes (NGTs). GTs were further divided into seven subtypes including the capitate, subsessile capitate, sessile capitate, sunken, barrel, peltate, and clavate. Similarly, NGTs were also divided into simple unicellular and multicellular including conical, falcate, cylindrical, dendrite, papillose, and short hook shape. Quantitative measurement includes the length and width of the trichomes, stomatal complex, epidermal cells, stomata, and trichomes index. Based on the foliar micromorphological characters, a taxonomic key was developed to delimit and correctly identify studied taxa. Further molecular, other anatomical and phylogenetic studies are recommended to strengthen the systematics of Lamiaceae.

Phenolic distribution in apple epidermal and outer cortex tissue by multispectral deep-UV autofluorescence cryo-imaging.

Phenolic compounds in fruit are involved in responses to biotic and abiotic stresses and are responsible for organoleptic properties. To establish the distribution of these secondary metabolites at the tissue and sub-cellular scales, mapping of fluorescence in apple epidermis and outer cortex tissue in cryogenic condition was performed after deep-UV excitation at 275 nm. Douce Moën and Guillevic cider apple varieties were sampled and frozen after harvest, after 30 days at 4 °C and after 20 days at room temperature. Image analysis of fluorescence emission images acquired between 300 and 650 nm allowed the assignment of fluorescence signals to phenolic compound families based on reference molecules. Emission attributed to monomeric and/or condensed flavanol was localized in whole tissue with major fluorescence in the cuticle region. Hydroxycinnamic acids were found predominantly in the outer cortex and appeared in the cell wall. Fluorescent pigments were mostly found in the epidermis. The distribution of flavanols in the sub-cuticle and phenolic acids in the outer cortex distinguished apple varieties. Storage conditions had no impact on phenolic distribution. The proposed fluorescent imaging and analysis approach enables studies on phenolic distribution in relation to fruit development, biotic/abiotic stress resistance and quality.

Phylogenomic analyses reveal an exceptionally high number of evolutionary shifts in a florally diverse clade of African legumes.

Detarioideae is well known for its high diversity of floral traits, including flower symmetry, number of organs, and petal size and morphology. This diversity has been characterized and studied at higher taxonomic levels, but limited analyses have been performed among closely related genera with contrasting floral traits due to the lack of fully resolved phylogenetic relationships. Here, we used four representative transcriptomes to develop an exome capture (target enrichment) bait for the entire subfamily and applied it to the Anthonotha clade using a complete data set (61 specimens) representing all extant floral diversity. Our phylogenetic analyses recovered congruent topologies using ML and Bayesian methods. Anthonotha was recovered as monophyletic contrary to the remaining three genera (Englerodendron, Isomacrolobium and Pseudomacrolobium), which form a monophyletic group sister to Anthonotha. We inferred a total of 35 transitions for the seven floral traits (pertaining to flower symmetry, petals, stamens and staminodes) that we analyzed, suggesting that at least 30% of the species in this group display transitions from the ancestral condition reconstructed for the Anthonotha clade. The main transitions were towards a reduction in the number of organs (petals, stamens and staminodes). Despite the high number of transitions, our analyses indicate that the seven characters are evolving independently in these lineages. Petal morphology is the most labile floral trait with a total of seven independent transitions in number and seven independent transitions to modification in petal types. The diverse petal morphology along the dorsoventral axis of symmetry within the flower is not associated with differences at the micromorphology of petal surface, suggesting that in this group all petals within the flower might possess the same petal identity at the molecular level. Our results provide a solid evolutionary framework for further detailed analyses of the molecular basis of petal identity.

Leaf epidermal micromorphology and its implications in systematics of certain taxa of the fern family Pteridaceae from Northern Pakistan.

The present study is insights into foliar epidermal anatomy for characterizing clades, and their utility in taxonomic segregation of certain species of Pteridaceae from Northern Pakistan. The leaf epidermal anatomy of 10 species of Pteridaceae representing four genera were examined using light and scanning electron microscope. A micromorphological matrix was constructed for eight qualitative and 12 quantitative characters. unweighted pair group method with arithmetic means and principal components analysis statistical analysis were performed to test the validity of foliar epidermal anatomical features as method of separating species and genera, and phylogenetic clusters among species are constructed using qualitative and quantitative traits. The qualitative characters described here are shape of epidermal cells, stomata, guard cell and subsidiary cells, anticlinal wall pattern, and trichomes types which is helpful in defining groups within Pteridaceae. In addition, the size of stomata, guard cells, subsidiary cells, stomatal pore epidermal cells, and trichomes are quantitatively analyzed. All species have hypostomatic leaves. Two types of stomata were observed in studied species, anomocytic and polocytic. Anomocytic stomata were observed in three genera namely: Adiantum, Onychium, and Chielanthes whereas Pteris can be discriminated from other genera by its polocytic stomata. On the basis of multivariate analysis present study does provides sufficient information on the taxonomic importance of foliar anatomy which validate its efficacy in species and genera discrimination. From result obtained here it is further possible to use leaf micromorphologic data in ferns phylogeny and providing basis for future taxonomic delimitation in other taxa.

Competition for epidermal space in the evolution of leaves with high physiological rates.

Leaves with high photosynthetic capacity require high transpiration capacity. Consequently, hydraulic conductance, stomatal conductance, and assimilation capacities should be positively correlated. These traits make independent demands on anatomical space, particularly due to the propensity for veins to have bundle sheath extensions that exclude stomata from the local epidermis. We measured density and area occupation of bundle sheath extensions, density and size of stomata and subsidiary cells, and venation density for a sample of extant angiosperms and fossil and living nonangiosperm tracheophytes. For most nonangiosperms, even modest increases in vein density and stomatal conductance would require substantial reconfigurations of anatomy. One characteristic of the angiosperm syndrome (e.g. small cell sizes, etc.) is hierarchical vein networks that allow expression of bundle sheath extensions in some, but not all veins, contrasting with all-or-nothing alternatives available with the single-order vein networks in most nonangiosperms. Bundle sheath modulation is associated with higher vein densities in three independent groups with hierarchical venation: angiosperms, Gnetum (gymnosperm) and Dipteris (fern). Anatomical and developmental constraints likely contribute to the stability in leaf characteristics - and ecophysiology - seen through time in different lineages and contribute to the uniqueness of angiosperms in achieving the highest vein densities, stomatal densities, and physiological rates.