Sinuous Anticlinal Walls Research Articles

Anatomical and micromorphological characteristics of Pogostemon heyneanus Benth. (Lamiaceae)

Foliar micromorphological and anatomical characteristics of Pogostemon heyneanus Benth. (Lamiaceae) was investigated in order to describe its comprehensive characterization and its association with the presence of essential oils. The methods used in this study involved several methods such as cross-section using a sliding microtome and epidermal peeling that were observed under light microscope, and foliar micromorphological characteristics that were observed under scanning electron microscope (SEM). Results showed leaf anatomical and micromorphological characteristics that could be useful in species identification and the localization of chemical properties. The leaf epidermal surfaces were characterized by curved to sinuous anticlinal walls (adaxial side) and sinuous anticlinal walls (abaxial side). The diacytic and anisocytic types of stomata were present only on the abaxial surface. The features of the stem is quadrangular and the well-developed collenchyma function. The sclerenchyma cells are present as clusters at the outer layer of vascular bundles and continuously surround the vascular tissue. Then, there were three forms of crystals found, namely star shaped crystals, prismatic crystals and raphides in the pith area. Eight types of trichomes were observed: simple unicellular, simple multicellular, peltate, short-stalked capitate (unicellular head), short-stalked capitate (bicellular head), short-swollen multistalked (unicellular acute head), long-stalked capitate, and long-swollen stalked capitate (disk head) trichomes. The presence of various glandular trichomes on the leaf surfaces may serve as secretory sites where secondary metabolites or essential oils are produced. The findings on the foliar and stem anatomical and micromorphological characteristics are very useful for the medicinal herbs industry as well as being of taxonomic value.

The Anatomy and Morphology of Taenitis Willd. ex Sprengel (Monilophytes) in Peninsular Malaysia

The present study investigates the anatomical and morphological characteristics of four Taenitis species sampled from several localities in Peninsular Malaysia, namely Taenitis blechnoides, T. interrupta, T. dimorpha and Taenitis sp. The morphological and anatomical characters were observered with compound and dissecting microscopes, and sliding microtome. The species exhibited varying frond sizes (length and width) and positions of sori. Conversely, all the species showed common short creeping rhizomes with black hairy scales, scales at the base of stipes, U-shaped steles, simple trichome, sclerenchyma cells under the epidermis on stipes and rhizomes, polocytic stomata, and sinuous anticlinal walls. Morphologically, the frond form of Taenitis sp. is distinct from the other Taenitis. Thus, the species could be a new record for ferns in Peninsular Malaysia. However, molecular studies are required to confirm this.

Leaf anatomy for delimiting Atlantic Forest species of Psidium (Myrtaceae)

Abstract Leaf anatomical features are widely used to better understand angiosperm taxonomy. However, such information is scarce for the family Myrtaceae. Aiming to fill this knowledge gap, we studied anatomical and micromorphological leaf characters of ten species of Psidium: P. cattleyanum, P. cauliflorum, P. corynanthum, P. guajava, P. guineense, P. macahense, P. myrtoides, P. oligospermum, P. ovale and P. sartorianum. Uniseriate epidermis, paracytic stomata, secretory cavities, and adaxial hypodermis are common among the studied species and are typical characteristics of Myrtaceae. The presence of three or more layers of palisade parenchyma and the absence of sclerenchyma are diagnostic characters of P. guajava. The abaxial epidermis of Psidium cattleyanum and P. macahense possess curved walls. Psidium corynanthum and P. macahense are the only species with sinuous anticlinal walls on both sides of the epidermis, with all other species having straight or curved walls. Open bicollateral vascular bundles are present in all the studied species except P. guineense. With the exception of P. cauliflorum, all the studied species possess druses. The absence of collenchyma in the adaxial face is exclusive to P. ovale. The leaf anatomy of P. macahense, P. corynanthum, P. oligospermum and P. ovale are described for the first time here.

Comparative Leaf Anatomy and Micromorphology of Thunbergia erecta (Benth.) T. Anderson and Thunbergia laurifolia Lindl. in Peninsular Malaysia.

Comparative leaf anatomy and micromorphology study was carried out on two selected species from the genus Thunbergia Retz. of Acanthaceae subfamily Thunbergioideae. These two investigated species were T. erecta and T. laurifolia from Peninsular Malaysia. The leaf anatomical study involve several methods such as cross-section using sliding microtome on the petioles, midribs, lamina and marginal, leaf epidermal peeling, leaf clearing and observation under a light microscope. The leaf micromorphology method involve the observation under a scanning electron microscope (SEM). This study aimed to investigate the taxonomic value of leaf anatomy and micromorphology characteristics of genus Thunbergia. The results have shown that there were five common characteristics present in both species studied and several variable characters that might be useful for species differentiation of T. erecta and T. laurifolia. The five common characteristics recorded were the presence of raphide, sinuous anticlinal walls, diacytic stomata, majority opened and minority closed venation in lamina and the presence of peltate glandular (unicellular terminal) trichome. The variable characteristics included were petiole, and marginal outlines, types of vascular bundles, the presence of druse, marginal venation, stomata occurrence, types of wax, cuticular sculpturing and types of trichomes. In conclusion, findings in this study showed that leaf anatomical and micromorphological characteristics possessed taxonomic value that can be used in the species identification for the genus Thunbergia specifically for T. erecta and T. laurifolia.

Seed micromorphology supports species delimitation of Orchis canariensis (Orchidaceae), an endemic orchid from the Canary Islands

Geographic isolation is one of the primary drivers of speciation, but islands remain a reservoir of overlooked and understudied endemic species. In this study, we collected seed micromorphological data from Orchis canariensis (Orchidaceae), a declining species occurring only on the Canary Islands (Spain), whose taxonomy was debated in the past decades. The aim of the study was to detect seed micromorphological traits in support of species delimitation by means of light and scanning electron microscopy. Seeds from a population on Tenerife resulted to be clavate with a cell number in the longitudinal axis varying from five to seven. Seeds showed straight to sinuous anticlinal walls and no ornamentations in the periclinal walls. The average seed length was 313.66 ± 44.78 µm and the average width 184.31 ± 30.26 µm, with a ratio of 1.72 ± 0.25, while the embryo length and width were 157.18 ± 35.21 µm and 125.43 ± 25.92 µm respectively. However, despite the affinities with the sister species, Orchis patens, quantitative and qualitative seed traits supported species delimitation recently proposed by means of molecular biology. Taken together, our results confirmed the importance of seed micromorphology in support of taxonomical studies.

TAXONOMIC IMPORTANCE OF ANTICLINAL WALLS AND STOMATA PATTERNING IN SOME MELASTOMA L. SPECIES FROM FRASER HILL

The epidermal characteristics of five selected Melastoma L. species in Fraser Hill, Pahang that belongs to Melastomataceae family had been investigated. These five species namely M. muticum Ridl., M. decemfidum Roxb., M. perakense Ridl., M. sanguineum x malabathricum and M. malabathricum var. normale. The objective of this study is to determine whether epidermal characteristics in Melastoma could be taxonomic value in systematic and diagnostic investigations. Methods of the investigation involved epidermal peel and scanning electron microscopy. Results obtained revealed that the presence of hypostomatic stomata and guard cells pairs were elliptic in shaped for all species studied. Apart, the pattern of anticlinal walls on adaxial and abaxial surfaces was straight to wavy for all species studied except for wavy to sinuous anticlinal walls on abaxial surface of M. sanguineum x malabathricum. Furthermore, two types of stomata were observed among species studied such as anomocytic and diacytic stomata. Results showed that diacytic type was only present in M. sanguineum x malabathricum therefore could be a criterion to diagnose the species. Lastly, this present study was also reported on the presence of two types of guard cell pairs such as raised or slightly raised and sunken guard cell pairs. In conclusion, the present study revealed that the anticlinal walls and stomata patterning possess as taxonomic importance in identification and classification of Melastoma either at genus or species level.

Anatomical characters used to delimit species of some genera of Brassicaceae in Iraq.

The anatomical characters of the leaf epidermal cells and trichomes of 13 species of Brassicaceae family were studied by light and scanning electron microscopy. The results showed cell walls thicker in Cheiranthus cheiri, Camelina rumelica, Biscutella didyma; and also, in lower epidermis of Crambe orientalis. While they were thin in Calepina irregularis, Lobularia maritima, Nasturtium officinale and Thlaspi perfoliatum. Cells of upper epidermis were with strongly undulate anticlinal cell walls in Capsella bursa-pastoris, Draba bruniifolia, Nasturtium officinale and Sameraria stylophora. Cells were with sinuous anticlinal walls in Calepina irregularis, Cheiranthus cheiri and Biscutella didyma. There were straight-sinuate anticlinal cell walls in the rest of the species studied.
 Five types of stomatal complex were found: 1. Anisocytic (Cruciferous), 2. Anomocytic (Rununculaceous), 3. Hemiparacytic, 4. Paracytic, in Cheiranthus cheiri, Crambe orientalis, Nasturtium officinale, Cardaria drapa subsp. draba and Thlaspi perfoliatum, and 5. Tetracytic in Cardaria draba and Thlaspi perfoliatum. The highest Stomatal index percent was 36.4% on the abaxial surface of Cheiranthus cheiri, and the lowest 7.81% in abaxial of Draba bruniifolia. 
 Eight trichome types are distinguished: Simple, T-shaped, Y-shaped, V-shaped, Vesiculate, Clavate, Dendroid, Stellate and Long membranous. In addition, glabrous species also were found.

Dispersed cuticles and conducting tissue of Sphenophyllum BRONGNIART from the Westphalian D of Kalinovo, Donets Basin, Ukraine

Upper Westphalian coals are usually rich in organic-matter of different plant taxa, including gymnosperms. The assemblagefrom Kalinovo (Eastern Ukraine) is exceptional in being dominated by Sphenophyllum , both cuticles andconducting tissues. Sphenophyllum cuticles are easily distinguished by their parallel oriented cells with sinuous anticlinalwalls, and paracytic stomata on the abaxial cuticle. Tracheids with multiseriate bordered pits that occur in Sphenophyllum can be also found in the Calamitaceae and some pteridosperms. However, rectangular shaped remainsof parenchyma cell strips along the radial wall of tracheids are only known in Sphenophyllum .

Pharmacobotanical study of the leaf and stem of Mikania lanuginosa for its quality control

Mikania lanuginosa DC, Asteraceae, is popularly known as “cipó-cabeludo” in Brazil due to a remarkable number of trichomes on its leaves and stems. It shows antimicrobial activity against Staphylococcus aureus, S. epidermidis and Bacillus cereus. This species can be confused with M. microlepis Baker and M. hirsutissima DC for substitution and tampering purposes. The aim of this study was to investigate the morpho-anatomy of leaf and stem of M. lanuginosa to obtain pharmacobotanical data that may contribute to its identification and taxonomic definition from other species of Mikania. The leaves and stems were investigated using scanning electron microscopy and light microscopy techniques. Mikania lanuginosa shows a uniseriate epidermis covered by a thin and smooth cuticle. The epidermal cells present sinuous anticlinal walls on both sides and anomocytic stomata were observed. A few glandular trichomes and numerous non-glandular trichomes were identified on both surfaces. The mesophyll is dorsiventral, the midrib has a biconvex contour and the petiole shows a circular shape in a cross-section. The stem has a circular shape. These pharmacobotanical features described for M. lanuginosa support data for its identification and taxonomic delimitation from other Mikania species, and are a contribution for the quality control of herbal drugs.

Morfología y anatomía de ejes caulinares, licofilos y esporangios de Phlegmariurus phylicifolius: un aporte a la sistemática de las Lycopodiaceae neotropicales

Phlegmariurus is the only genus of Lycopodiaceae with the species grouped in 22 informal groups. Species level relationships within Phlegmariurus are poorly understood and their circumscriptions require a thorough molecular and morphological review. A detailed study of morphology and anatomy of caulinar axes, lycophylls and sporangia of Phlegmariurus phylicifolius was carried out in order to contribute to the elucidation of species circumscription in the informal group Phlegmariurus phlegmaria. Small pieces of caulinar axes bearing trophophylls, sporophylls and sporangia were fixed, dehydrated, Histowax (paraffin) embedded, sectioned in a rotatory microtome, and stained using the common Safranin O-Fast Green technique; handmade cross sections were also made and stained with the same technique. P. phylicifolius includes slender, pendulous plants up to 40cm long. Shoots heterophyllous, in the basal divisions ca. 10-20(-25) mm in diameter including the trophophylls, then abruptly constricted to (1-) 1.5-2(-2.5) mm in diameter including the imbricate, reduced sporophylls. Trophophylls are borne in alternating whorls of three, or decussate, subdecussate, or alternate, widely spaced in alternate leaved caulinar axes portions, perpendicular to the caulinar axes to falcately ascending, lanceolate to linear-lanceolate, with flat to slightly revolute margins. Each lycophyll is supplied by a single central vascular bundle, connected to a protoxylem pole in the stele. At the site of leaf-trace departure, no leaf (lycophyll) gap is present. Caulinar axes excluding leaves 0.7-1.2 mm thick at the base, upward tapering to ca. 0.5 mm. Caulinar axes present unistratified epidermis and endodermis, the cortex is characterized by the presence of a trabecular structure of lisigenous origin formed in the parenchimatous tissue next to the endodermis. The vascular tissue occupies the central part of the caulinar axes, forming a plectostele ofsubradiate organization, with five poles ofprotoxylem. The epidermal cells present sinuous anticlinal walls; invaginations in the inner side of external periclinal wall of the epidermal cells could be probably adaptive morphological feature of a water deficient environment. Leaves of constricted terminal divi- sions are decussate, or subdecussate, continuously or discontinuously sporangiate, appressed, abaxially rounded to carinate, widely lanceolate to widely ovate or subcordate, acute to mucronate or cuspidate, shorter than the sporangia. Each sporangium originates from a group of epidermal cells, axilar to the sporophylls. The cell walls of epidermal cell of the sporangia are Huperzioideae type. The morphological studies of trophophylls contribute to confirm the differences between P. phylicifolius and P. subulatus.

Epidermal studies of three species of Vernonia Schreb. in Southern Nigeria

Kemka-Evans CI, Okoli B, Nwachukwu CU. 2014. Epidermal studies of three species of Vernonia Schreber in Southern Nigeria. Biodiversitas 15: 137-141.The leaf epidermal studies of three species of Vernonia namely V. cinerea (L) Less, V. amygdalina Delile.(bitter leaf and non-bitter leaf variety) and V. conferta Benth. were undertaken with the aim of revealing their foliar characters whichwill enhance their identification and determination of their taxonomic relationship. Matured leaves were soaked in Sodium OxochlorateII for 24hours to separate the epidermal surfaces. Data from the measurement of stomata and epidermal cells were analyzed. Thepresence of diagnostic characters such as contiguous stomata and sinuous anticlinal walls on the abaxial leaf surface of non-bitter varietyof V. amygdalina and on both leaf surfaces (adaxial and abaxial) of V. cinerea are of taxonomic importance. The irregular T-shapedtrichomes on the leaf surfaces of V. amygdalina (bitter leaf) and the cuticular striations on the adaxial surface of the same taxa could beused to delimit the taxa from the other species. The distribution of the stomata show hypoamphistomatic in all the three species studied.Anomocytic stomata occurred on all the taxa studied. Anisocytic stomata were found on the abaxial surface of V. conferta. Thesecharacters examined revealed interspecies relationship among the three species and also suggest that V. amygdalina (non bitter leaf) is avariety of V. amygdalina (bitter leaf) and should not be regard as another species of Vernonia. The epidermal leaf characters of V. amygdalina (non-bitter leaf) is also been reported for the first time.

Characters of leaf epidermis in Solanum (clade Brevantherum) species from Atlantic Forest of Northeastern Brazil

Solanum is the richest and most diverse genus of the Solanaceae and one of the largest among angiosperms. The high number of species in the genus and the morphological plasticity of vegetative organs make the taxonomy of the group quite complex. We carried out an anatomical study of the leaf epidermis of six species of the Brevantherum Clade occurring in the Atlantic Forest of Northeastern Brazil (Solanum asperum, Solanum maranguapense, Solanum anisocladum, Solanum rugosum, Solanum stipulaceum and Solanum swartzianum), in order to support their taxonomy. Analyses were performed by the usual techniques for leaf anatomy, followed by light and scanning electron microscopy. All species showed leaf epidermis cells with sinuous anticlinal walls, and anisocytic stomata. Anomocytic stomata were also observed in S. asperum, S. anisocladum and S. swartzianum. Except for S. stipulaceum with amphistomatic leaves, the hypostomatic pattern was predominant. A great diversity of stellate trichomes was observed, mainly porrect-stellate and multiangulate, and peltate trichomes were only observed in S. swartzianum. The characters of leaf epidermis and its annexes, mainly the morphology of trichomes, are useful in distinguishing the Solanum species (clade Brevantherum) from Northeastern Brazil.

Leaf Epidermal Micromorphology of Portulaca L. Species Found in Vadodara, Gujarat, India

Micromorphology of three species of Portulaca was carried out with the help of light microscopy to determine variations within the species which would aid in correct identification of the plants. Epidermal cells are polygonal with sinuous anticlinal walls in all the three species. Length of epidermal cells of P. grandiflora Hook. is higher than P. oleracea Linn. and P. quadrifida Linn. The leaves of P. quadrifida are epistomatic while the remaining species are amphistomatic with paracytic stomata in all the three species. Mean stomatal index and stomatal frequency are more in P. quadrifida while the mean size of stomata (both length and width) is larger in P. grandiflora for both adaxial and abaxial surfaces. Based on the diagnostic features, an artificial indented key is prepared.

Plinia edulis - leaf architecture and scanning electron micrographs

Many species of Myrtaceae, including Plinia edulis (Vell.) Sobral (cambucá), have pharmacological properties and are used as hypoglycemiants and therapeutic agents against stomach problems and throat infections. Samples were collected from Tijuca Forest in Rio de Janeiro, and the morpho-anatomical data were compared with other specimens obtained from Trindade, Paraty, found in the literature. Variations in leaf anatomy were observed, and the possible causes for these effects are discussed. The plant material collected from Tijuca Forest was analyzed using scanning electron and optical microscopy. Histochemical tests were applied to identify starch, lipids, phenolic compounds and lignin. The epidermal cells exhibit straight or slightly sinuous anticlinal walls covered by a smooth cuticle with granules of wax. Simple trichomes are restricted to the midrib region, and paracytic stomata are only observed on the abaxial leaf surface. The mesophyll is dorsiventral, with conspicuous intercellular spaces in the spongy parenchyma. Intercalated columns of crystalliferous cells and subepidermal secretory cavities are observed in the single layer of palisade parenchyma. The samples obtained from Trindade, Paraty, show larger leaves, anomocytic stomata and trichomes scattered throughout the leaf surface. This plasticity might reflect leaf adaptations to environmental factors or different stages of leaf development.

Anatomia foliar de espécies de <I>Eugenia</I> L. (Myrtaceae) oriundas da restinga de Algodoal/Maiandeua-Pará

The increase in the number of species of Myrtaceae analyzed anatomically is needed to verify the reliability of higher taxonomic inferences. In order to contribute with structural data to Myrtaceae family and to Eugenia genus, the leaf anatomical structure of E. biflora (L.) DC., E. flavescens DC., E. patrisii Vahl. And E. tapacumensis Berg. arising from the sandy coastal Algodoal/Maiandeua-Pará was described. Some characteristics were irrespective of the four examined species: adaxial surface of epidermal cells with sinuous anticlinal walls; thick leaf cuticle; non-glandular unicellular trichomes; hypostomatic leaves; paracytic and anomocytic stomata; dorsiventral mesophyll; secretory cavities with positive oil content, principally at palisade parenchyma; secretory idioblasts with positive phenol and oil contents; bicollateral bundle on the midrib and petiole. The leaf anatomical structure of four examined species of Eugenia showed universal features to Myrtaceae.

Secretory structures of Ipomoea asarifolia: anatomy and histochemistry

Ipomoea asarifolia (Desr.) Roem. & Schult., Convolvulaceae, is a weed that infests agricultural areas and is toxic to cattle. In spite of its toxicity, the leaves of this plant are used in traditional remedies in the state of Bahia, Brazil. The present work describes the leaf anatomy of I. asarifolia and characterizes the exudates of its secretory structures. The leaves have a unistratified epidermis composed of ordinary cells with straight to slightly sinuous anticlinal walls and thin cuticles. Paracytic stomata are found on both surfaces of the leaves at the same level as the ordinary epidermal cells. Trichomes producing polysaccharide secretions occur on the petiole and leaf blade and are considered colleters. The mesophyll is dorsiventral and the vascular bundle of the central vein is bicollateral. Two opposed nectaries occur on the petiole near the leaf blade. Each nectary is composed of a small canal with internal ramifications and numerous secretory trichomes. The laticiferous glands are articulated, not anastomosed, and are composed of large diameter cells with thin cell walls. The secretions of the laticiferous glands are lipidic.

Evolution of lamina anatomy in the palm family (Arecaceae)

The unique properties of tree building in Arecaceae strongly constrain their architectural lability. Potentially compensating for this limitation, the extensive diversification of leaf anatomical structure within palms involves many characters whose alternate states may confer disparate mechanical or physiological capabilities. In the context of a recent global palm phylogeny, we analyzed the evolution of 10 such lamina anatomical characters and leaf morphology of 161 genera, conducting parsimony and maximum likelihood ancestral state reconstructions, as well as tests of correlated evolution. Lamina morphology evolves independently from anatomy. Although many characters do optimize as synapomorphic for major clades, anatomical evolution is highly homoplasious. Nevertheless, it is not random: analyses indicate the recurrent evolution of different cohorts of correlated character states. Notable are two surface layer (epidermis and hypodermis) types: (1) a parallel-laminated type of rectangular epidermal cells with sinuous anticlinal walls, with fibers present in the hypodermis and (2) a cross-laminated type of hexagonal cells in both layers. Correlated with the cross-laminated type is a remarkable decrease in the volume fraction of fibers, accompanied by changes in the architecture and sheath cell type of the transverse veins. We discuss these and other major patterns of anatomical evolution in relation to their biomechanical and ecophysiological significance.

Effect of the culture environment on stomatal features, epidermal cells and water loss of micropropagated Annona glabra L. plants

Shoots of Annona glabra L. were rooted in vitro under three levels of irradiance and two closure systems (conventional and natural ventilation) of the culture vessels. Once the shoots had been rooted, we studied how the manipulation of the culture environment affects the stomata features and water loss through leaf tissues after the plants are removed from the vessel. The stomata frequency increased significantly in the leaves of plants grown under high (300 μmol m −2 s −1) compared to low (50 μmol m −2 s −1) or intermediate (150 μmol m −2 s −1) irradiance, with higher effect under natural ventilation. Irrespective of the culture environment, leaves developed in vitro attained a higher stomata frequency than those grown in vivo. Under high irradiance and natural ventilation, the leaves presented functional stomata of characteristically elliptical shape and the epidermal cells were smaller and had slightly sinuous anticlinal walls. Besides, water loss through leaves of plants grown under high irradiance and natural ventilation was drastically reduced if these plants were exposed to an environment with low relative humidity thereafter. Our results indicate that an increased light availability and the use of natural ventilation improve the regulatory capacity of water loss in micropropagated A. glabra L. plants and can favor the plants’ survival and growth after transference to the natural environment.

Bulliform cells in Loudetiopsis chrysothrix (Nees) Conert and Tristachya leiostachya Nees (Poaceae): structure in relation to function

This work reports anatomic and ultrastructural characteristics of bulliform cells in Loudetiopsis chrysothrix (Nees) Conert and Tristachya leiostachya Nees. Both the species presented leaf rolling under water stress. The main characteristics observed in these cells were: periclinal wall thinner than the adjacent epidermal wall; abundance of pectic substances in cuticular layer; sinuous anticlinal walls with ramified plasmodesmata; vacuome formed by a developed vacuole or innumerous small vacuoles; abundance of phenolic substances and oil drops. These characteristics suggested the involvement of bulliform cells in the mechanism of foliar involution in the studied species.

Morfologia externa e interna das folhas vegetativas, esporofilos e esporângios de espécies de Huperzia Bernh. (Lycopodiaceae - Pteridophyta) do Brasil

Lycopodiaceae belongs to the Lycopsida, which autapomorphy is the presence of microphyllous leaves. It was studied 10 species, and seven are endemic to Brazil: the terrestrials Huperzia christii (Silveira) Holub, H. friburgensis (Nessel) B. Ollg., H. hemleri (Nessel) B. Ollg., H. intermedia Trevis., H. reflexa (Lam.) Trevis. and H. treitubensis (Silveira) B. Ollg.; the epiphytics H. fontinaloides (Spring) Trevis., H. heterocarpon (Fee) Holub, H. hexasticha B. Ollg. & P.G. Windisch and H. quadrifariata (Bory) Rothm. The anatomical features found that are probably adaptive to a water deficient environment are the presence of epidermal cells with sinuous anticlinal walls, invaginations in the inner side of external periclinal wall of the epidermal cells and amphiestomatic leaves. The analysed species were separated in two groups, corroborating existing classifications. The two groups were defined on the basis of the following characters: phyllotaxis helical or opposite, leaf position in relation to the stem, if reflexed or adpressed, and the number of sporangia cell layers, if three or four. An identification key was elaborated.