Bicollateral Bundles Research Articles

Vegetative anatomy of five domesticated members of the genus Cucurbita (Linn.) in Southwestern Nigeria

The vegetative anatomy of five domesticated species of the genus Cucurbita L. found in South Western Nigeria was studied. The aim was to establish some useful diagnostic features that may be employed in combination with other characters as intra or inter-specific or generic tools for their delimitation. The study revealed exciting features that are helpful in the identification of each species. The genus can be divided into three groups based on the shape of the midrib. Those with a U-shape are C. pepo, C. argyrosperma and C. ficifolia. C. maximum has a round/flat shape while C. moschata has V shape. Those with a U-shape can further be classed into those with a wide and narrow neck. C. argyrosperma has narrow neck with two vascular bundles, four layers of palisade tissues and 6 layers of abaxial epidermis. C. pepo has a wide neck with three bicollateral bundles and two layers of palisade tissues while C. ficifolia has two bundles and three layers of palisade tissues. Overlaps and similarities in the number of vascular bundles, and layers of tissues showed generic affinity among the members.

Anastomosing laticifer in the primary and secondary structures of Calotropis procera (Aiton) W.T.Aiton (Apocynaceae) stems.

An in-depth understanding of the development and distribution of laticifer (latex secretory structure) will be important for the production of both rubber and medicines and will support studies on plant adaptations to their environments. We characterize here and describe the ontogenesis of the laticifer sytem in Calotropis procera (Apocynaceae), an invasive subshrub species in arid landscapes. Anatomical and histochemical evaluations of the primary and secondary structures of the stem were carried out on a monthly basis during a full year, with ultrastructural evaluations of laticifer on the stem apex during the rainy season. In the primary structure, laticifer differentiate early from procambium and ground meristem cells of the cortex and medulla and become concentrated adjacent to the external and internal phloem of the bicollateral bundles. In the secondary structure, laticifer differentiates from fusiform derivative cells of the phloem close to the sieve-tube elements. The laticifer is of the articulated, anastomosing, branched type, and it originates from precursor cells that loose the transversal and longitudinal walls by dissolution. Latex is a mixture of terpenes, alkaloids, flavonoids, mucilage, and proteins. The apical meristem and vascular cambium where the laticifer system begins its development are active throughout the year, including during the dry season. The vascular cambium produces phloem with laticifer precursor cells during the rainy season, with high temperatures and long days. The ability of C. procera to grow under water deficit conditions and produce laticifer throughout the year contribute to its wide distribution in arid environments.

Pharmacognostic Studies of the Leaves and Fructus of Arctium lappa L. (Asteraceae Bercht. & J. Presl)

Introduction: The state quality assurance system ensures the confidence of consumers that the product meets its quality requirements. In this study, pharmacognostic standards of the leaves and fructus of burdock are specified for the first time. Methods: Microscopic analysis was carried out by using the microscope Carl Zeiss. The UV spectrum were measured on an SF-2000 spectrophotometer. Results: Macroscopically, the leaves are heart-shaped, broad-heart-ovate-shaped with a spaced emarginatedserrate or whole edge, with a wide, wedge-shaped, rounded, uneven base, acute apex, green on the outer surface, grayish slightly pubescent on the inner surface. The fructus are obovate or wedge-compressed, slightly curved, the color is brown/black with spots, or variegated with black spots on a gray background. The microscopic examination of the leaves revealed the presence of epidermis, large submerged and non-submerged stomata of the anomocytic type, 2 types of simple unbranched multi-cellular and glandular capitate trichomes; essential oil glands. Microscopic examination of the leaf petiole revealed the presence of 2 types of simple multi-cellular trichomes, epidermis, angular collenchyma, bicollateral bundles, parenchyma. The stomatal index value is 8.28±0.81 per 1cm2. The microscopy of the fructus revealed the presence of elongated cells of the pericarp epidermis; mesocarp; endocarp; endosperm with aleurone grains and drops of fatty oil. The qualitative phytochemical analysis of revealed the presence of polysaccharides, tannins, flavonoids, terpenoids, saponins, phenolic acids. Conclusion: Physical and chemical parameters (moisture, extractive value, ash content) were also specified. These specific data are important for establishing diagnostic indicators for standardization, identification, preparation of new quality standards.

Morphology, Anatomy, Palynology and Seed Micromorphology of Turkish Endemic Verbascum exuberans Hub.-Mor. (Scrophulariaceae)

ABSTRACT: Verbascum L. is the largest genus of the family Scrophulariceae and includes several species are of medicinal importance. The high morphological diversity among the species of the genus Verbascum causes problems in the delimitation of the species. In this study, morphological, anatomical, palynological and seed properties of Verbascum exuberans were investigated. It is a local endemic restricted to the provinces of Manisa and Izmir in West Anatolia. In the root cross-section, the xylem elements occupy a considerable area. The upper part of the epidermis cells in the stem cross-section is covered a distinct cuticle layer. The main vein of the leaf is shapped as bicollateral bundle. Idioblasts were not observed in the epidermis of the leaves of V. exuberans. Seeds of V. exuberans are dark brown and oblong to prismatic and alveolate. Hilum is short and orbicular. The seed coat ornamentation is reticulate-rugose. Pollen grains usually radially symmetrical, isopolar, prolate, tricolpate. Tectum is reticulate.

Use of Frozen Leaves for Morpho-anatomical Characterization of Nectandra megapotamica (Spreng.) Mez., Lauraceae

Nectandra megapotamica (Spreng.) Mez. it is a native tree species of the Atlantic Forest, commonly known as canela-preta. The species has some anti-inflammatory, antitumor and antirheumatic properties among others. In this work the use of frozen plant material for microscopy analysis was tested. In addition, the leaf morpho-anatomy of the species was characterized which allowed to perform a structural description and to identify structures of secretion and storage of essential oil. The plant material was prepared for analyzes in optical, fluorescence and scanning electron microscopy. The leaf anatomy shows glabrous epidermis, unistratified, paracytic stomata, absence of trichomes, polyhedral epidermal cells. Some typical family characteristics were observed as a closed arc-shaped bicollateral bundle vascular system and dorsiventral mesophyll. The structures of secretion and storage of essential oil were identified as secretory cavities.

Micro-morphological study of Evolvulus spp. (Convolvulaceae): the old world medicinal plants.

BackgroundSeveral medicinal properties have been reported for plants in the genus Evolvulus, such as a brain tonic and antifungal from Evolvulus alsinoides, and a sedative and an anthelmintic from Evolvulus nummularius. Therefore, the correct identification of the source plants is critically important. The aim of this research was to investigate the micromorphology of two Evolvulus taxa used for herbal medicines compared with one worldwide ornamental species by using peeling, paraffin embedding, acetolysis, and SEM methods in order to support species identification.ResultsOur findings indicate that all taxa share several common features, such as a single layer of epidermis on both sides of leaf surfaces, sinuous anticlinal epidermal cell walls, anomocytic, paracytic or laterocytic stomata, and capitate glandular trichomes. Y-shaped hairs were found in two species but not in E. nummularius. Similarly, isobilateral mesophyll occurs in both E. alsinoides and Evolvulus glomeratus, but a dorsiventral mesophyll is present in E. nummularius. Stems consist of a single layer of epidermis, one to four chlorenchyma layers, one to seven layers of cortical cells and a bicollateral bundle with pith in the center. The seed coat epidermal cell shapes were irregular or polygonal with raised and undulated anticlinal boundaries, and folded or flattened to concave periclinal walls. Pollens of all taxa are monads, spheroidally shaped with 28–47 µm diameter, and 15-pantocolpate apertures type with microechinate ornamentation.ConclusionsAn identification key to species is constructed based on leaf anatomy and seed coat characters. This data can be used in other subjects such as pharmaceutical botany, organic chemistry, taxonomy and horticulture, in terms of species identification.

Morphoanatomic characterization of the stem and the leaf of Tabernaemontana catharinensis A.DC (Apocynaceae) and antimutagenic activity of its leaves

ABSTRACT Tabernaemontana catharinensis A. DC (Apocynaceae) is used as a medicinal plant by the population. In order to contribute to the safe use of the plant as herbal medicine, this study aimed to morphoanatomically characterize the aereal vegetative organs of T. catharinensis and to evaluate the leaves’ mutagenic and antimutagenic activities. Histological blades of leaves and stem of T. catharinensis were performed; the methionine system (methG1) and Aspergillusnidulans conidia germination analysis were employed for mutagenic and antimutagenic evaluation. The morphoanatomic analysis did not show trichomes in the stem, petiole and leaf. Besides, it was observed both the presence of bi-collateral bundles - except in the foliar apex where the bundles were from the collateral type - as well as anamphistomatic leaf with paracyte stomata and sub-epidermal layer in the region of the leaf edges. The mutagenicity/antimutagenicity trial indicated a significant decrease of mutation frequency in comparison with the control group and showed that the T. catharinensis had antimutagenic activity within the type, time and form of treatment. Since the germination test showed that the conidia germination was accelerated from the bud phase, activities at the cell cycle level and polarized growth proved to be possible. The morphoanatomic analysis of the leaf and stem associated with the mutagenic and antimutagenic analyses contributes to the safe use of the plant by humans and also for the quality control of a possible phytotherapeutic drug.

Interxylary phloem: Diversity and functions

Interxylary phloem is here defined as strands or bands of phloem embedded within the secondary xylem of a stem or root of a plant that has a single vascular cambium. In this definition, interxylary phloem differs from intraxylary phloem, bicollateral bundles, pith bundles, and successive cambia. The inclusive but variously applied terms included phloem and internal phloem must be rejected. Histological aspects of interxylary phloem are reviewed and original data are presented. Topics covered include duration of interxylary phloem; relationship in abundance between sieve tubes in external phloem and interxylary phloem; distinctions between interxylary and intraxylary phloem; presence of parenchyma, fibers, and crystals in the interxylary phloem strands; development of cambia within interxylary phloem strands; three-dimensionalization and longevity of phloem, systematic distribution of interxylary phloem; physiological significance; and habital correlations. No single physiological phenomenon seems to explain all instances of interxylary phloem occurrence, but rapidity and volume of photosynthate transport seem implicated in most instances.

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.

ESTUDO FARMACOBOTÂNICO DAS FOLHAS DE MOMORDICA CHARANTIA L. (CUCURBITACEAE)

Momordica charantia L. é uma trepadeira pentencente à família Cucurbitaceae e conhecida no Brasil principalmente por melão-de-são-caetano. Na medicina popular, é empregada no tratamento do diabetes, lesões cutâneas, Apresenta propriedades febrífugas, cicatrizante e anti-reumática, sendo utilizada pela população principalmente como antidiabética. Esta pesquisa teve por objetivo analisar caracteres morfo-anatômicos de folhas dessa espécie a fim de contribuir para o controle de qualidade farmacognóstico do vegetal. A descrição morfológica foi realizada a vista desarmada e com auxílio de estreomicroscópio. Para a morfodiagnose microscópicas, secções transversais da lâmina e pecíolo e paradérmicas da lâmina foram coradas com fucsina básica e azul de Astra e analisadas em microscópio óptico. As folhas mostraram ser simples, membranáceas e orbiculares. O pecíolo apresentou colênquima angular e feixe vascular bicolateral. A região do limbo tem mesófilo dorsiventral e nervura central de contorno biconvexo com feixes bicolaterais e colaterais. Estruturas secretoras, tricomas tectores e glandulares e drusas de oxalato de cálcio estão presentes nas folhas.

Anatomia foliar de espécies de Myrtaceae: contribuições à taxonomia e filogenia

Trabalhos taxonômicos e filogenéticos têm utilizado informações anatômicas e para contribuir com estes estudos examinaram-se cortes paradérmicos e transversais da porção mediana foliar de Campomanesia adamantium (Camb.) O. Berg, Myrcia cordiifolia DC., M. decrescens O. Berg e M. torta D.C. Os caracteres anatômicos foram comparados com os de outras espécies descritas na literatura. São características comuns às quatro espécies examinadas: epiderme uniestratificada, tricomas unicelulares, folhas hipoestomáticas, estômatos paracíticos, cavidades secretoras em ambas as faces, mesofilo dorsiventral e nervura mediana com feixes bicolaterais. Destacam-se os seguintes caracteres úteis para a taxonomia da família: formato das células comuns da epiderme, tricomas dibraquiados ou não, camadas celulares incolores subepidérmicas e formato da nervura mediana. O formato e número das células teto das glândulas foliares têm utilidade taxonômica. O exame de 144 exsicatas evidenciou que a glabrescência é um fenômeno comum. A queda dos tricomas pode ser devido à sua base estreita e à ausência de célula pedal nos mesmos. Analisaram-se os caracteres à luz de estudos filogenéticos recentes e do ponto de vista ecológico, destacando a hipótese relacionada às células epidérmicas com possível função de célula de transferência. As características anatômicas forneceram dados para análises comparativas mais amplas entre os táxons de Myrtaceae e possibilitaram a construção de um cladograma, onde espécies de Leptospermum e Eucalyptus ocuparam posição basal, em consonância com filogenias relatadas na literatura.

Internal phloem in an interspecific hybrid of cassava, an indicator of breeding value for drought resistance

We examined the stem anatomy of Manihot esculenta Crantz and its hybrid with M. oligantha Pax. Cross-sections were stained with safranin-alcian blue. Manihot esculenta and its hybrid were found to have the same vascular structure in bicollateral bundles with internal phloem, which has been associated with drought resistance in other plant groups. If this association is established for cassava, it would facilitate the selection of lines that are more adapted to arid regions. This is the first report of internal phloem in this genus.

MORFODIAGNOSE DE Psidium guajava L., MYRTACEAE

Psidium guajava L., denominada popularmente de goiabeira, é uma espécie arbustiva a arbórea de pequeno porte, pertencente à família Myrtaceae e nativa da América tropical. As folhas são empregadas na medicina tradicional para tratamento de diarréia, disenteria e cólica abdominal. Possui flavonóides, em especial quercetina, tendo sido comprovadas as atividades antidiarréica, espasmolítica, antimicrobiana e antioxidante. Este estudo analisou a anatomia foliar e caulinar de P. guajava, com o objetivo de fornecer dados morfodiagnósticos aplicáveis ao controle de qualidade. O material vegetal foi fixado, seccionado à mão livre e corado com azul de astra e fucsina básica. Testes microquímicos foram também realizados. A folha é hipoestomática, com estômatos paracíticos, e apresenta tricomas tectores unicelulares. No limbo, ocorrem epiderme uniestratificada, camadas subepidérmicas parenquimáticas junto à superfície adaxial e cavidades secretoras. O mesofilo tende a dorsiventral e a nervura central e o pecíolo são percorridos por um feixe vascular bicolateral envolto por bainha esclerenquimática. O caule apresenta cilindros vasculares contínuos de floema externo, xilema e floema interno, atravessados por raios estreitos. Cristais de oxalato de cálcio e células com conteúdo fenólico ocorrem na folha e no caule. Palavras-chave: Anatomia, farmacognosia, flavonóides, goiabeira, planta medicinal

The biology of myco-heterotrophic ('saprophytic') plants.

SUMMARY More than 400 species of vascular plants, in 87 genera, are acholophyllous and heterotrophic, but not directly parasitic upon autotrophs. They are usually, but incorrectly, described as 'saprophytes’since they are in fact nourished by means of specialized mycorrhizal associations. Although distributed world-wide, they are most abundant and show the greatest species-richness in the Neotropics and Palaeotropical regions. Their aerial parts range in size from a few centimetres to extensive liane types up to 40 m long. With few exceptions, their habitats are dense moist forests in which there is a surface accumulation of leaf litter, often in situations which are too shaded for autotrophic growth. Although the achlorophyllous mycorrhizal mode of life has evolved independently many times and in widely disparate taxonomic groups, such plants show strong convergent evolution in particular adaptations to their peculiar mode of life. Most prominant amongst these are reductions in the size of seed and embryo, and the lack of differentiation of the embryo at maturity. The number of seeds produced by each flower is typically very large and the shape, structure and surface features of seeds involving adaptation for wind dispersal show remarkable parallels in many species. Specific adaptations for zoochory are rare but well developed in a small number of genera, some of which produce scents like fungal fruit bodies or floral parts which mimic fungal sporocarps. Vegetative parts are often even more conspicuously reduced. Most myco-heterotrophs are entirely subterranean for most of their lives and these stages exhibit adaptations consistent with a change in function from organs of absorption to organs of storage, shown by the almost universal loss of root hairs, decrease in surface area as exhibited in short cylindric‘vermiform’and tuberous roots or, in extreme cases, the complete suppression of roots and the formation of a swollen tuber or rhizome. Increased width of the root cortex often accommodates mycorrhizal infection and stores of carbohydrates and other materials obtained from the fungal symbiont. Mycorrhizal infection is confined to the below-ground parts of the plants but may be found there in modified stems as well as in roots. In many genera, stems are exceptionally slender and thread-like and their vascular tissues are either reduced to a single narrow cylinder of bicollateral bundles or, minimally, to four or six narrow bundles in the cortex. Secondary thickening is poorly developed in all but a tiny minority of species, lignification being confined to annular or, rarely, a few scalariform xylem vessels. Phloem is present in very small amounts and then mainly as parenchyma with sieve tubes frequently recorded as narrow and possibly with abherent sieve plates. Leaves are typically reduced to widely spaced achlorophyllous scales on the inflorescence axis. Occasionally, they are present only on underground rhizomes or tubers. The vascular supply to the leaf-scales, normally reduced to a single trace, may be absent. Vestigial stomata are sometimes found on leaves and, in a few species which retain traces of chlorophyll, on shoots but, in most fully heterotrophic species, stomata are absent from aerial parts. Since their seeds are very small and contain minimal reserve carbohydrates, the germination of myco-heterotrophs in nature would appear to depend upon infection by an appropriate symbiotic fungus at an early stage. The nature of the carbohydrates transferred from the fungus to the plants has not been determined. Once acquired from The fungal partner, most plants store carbon in a variety of forms, the most common of which is starch, although other compounds including glucomannan, fructan and calcium oxalate art important in some specks. Asexual reproduction is frequently important with root tubers, tubercles and rhizomes providing the means of vegetative spread. Nonetheless, all the angiospermous species recorded to date also reproduce sexually. Floral structures show varying degrees of reduction concomitant with myco-heterotrophy. Inflorescences are typically small, often with a single terminal flower, and the floral parts often show extreme simplification, with the production of unilocular or, more rarely, bilocular and trilocular ovaries. In some of the most highly adapted species, there is reduction of integumentary layers surrounding each ovule from the normal bitegmic condition to unitegmic or, occasionally, ategmic. With the principal exception of the Monotropaceae, placentation is typically trimerous and parietal. Flowers normally appear to be cross-pollinated and are brightly coloured. nectiferous, occasionally scented, and can demonstrate extreme morphological adaptations which attract insects as in the production of lone caudate tepals or fungus-mimicking structures. Much is still to be learned about the adaptive features and especially about the physiology of these plants and of their early developmental stages during which the essential associations with fungi are established. Similarly, studies of the taxonomy and physiology of most of their fungal partners are still in their infancy.

Stem Development, Medullary Bundles, and Wood Anatomy of Croton Glandulosus Var. Septentrionalis (Euphorbiaceae)

Anatomy and development of vascular tissues in the annual stems of Croton glandulosus var. septentrionalis are described. In primary stages of growth the stem possesses a eustele of bicollateral bundles; internal phloem is notably more extensive than the external. In addition to a vascular cambium and secondary xylem that form in the usual fashion, additional cambia add cells to the internal phloem portion of the bicollateral bundles, forming well-marked medullary bundles at the perimeter of the pith. At first, the perimedullary cambial strands produce only internal secondary phloem; later, internal secondary xylem is also formed in some stems. When internal secondary xylem is present, the medullary bundles have an inverted orientation, i.e., phloem innermost (towards centre of pith) and xylem outermost (near protoxylem). Cells of the medullary bundles include sieve tube elements, vessel ekments, and fibres. Normal (external) secondary phloem is weakly developed. Normal secondary xylem contains short vessel elements with simple perforation plates and alternate intervascular pits, libriform fibres, narrow heterocellular rays, and lacks axial parenchyma.

Comparative Anatomy and Morphology of Asclepias perennis and Asclepias tuberosa Subspecies Rolfsii

Plants of Asclepias perennis Watt. and A. tuberosa L. ssp. rolfsii are examined to determine structural characteristics of these species from different habitats. Some structural features in both species are related to growth habit. Stomata occur more frequently on the adaxial surface of the leaves of both species from the dry, sunny sites and are more abundant on the abaxial surface in leaves of A. perennis from these sites. The dorsiventral leaves have well-developed palisade and spongy mesophyll layers and are thicker in plants from the dry, sunny sites because of a large palisade mesophyll. Leaves of both species have greater length-to-width ratios in plants from the dry, sunny sites than from wet, shaded sites. Bicollateral bundles constitute the midrib and major veins of the leaves and petiole bundles, while collateral bundles constitute the minor veins of the leaves. Druse-containing cells and branched, nonarticulated laticifers occur in the leaves and stems of both species and also are found in the...

Reproductive Anatomy and Morphology of Myrtales in Relation to Systematics

Evidence from reproductive morphology and anatomy (excluding palynology) favors an inclusive Myrtales of 11 core families (see below) over either a much broader Myrtales, as advocated, for example, by the Englerian school (most recently Melchior, 1964) or a narrower Myrtales and accompanying Lythrales, as advocated by Novak (1961, 1972) and more recently and in a rather different manner by Briggs and Johnson (1979), who, however, withdrew their concept in this symposium (Johnson & Briggs, 1984; see also argumentation in the appendix in Schmid, 1980). Embryology provides the best evidence for a concept of core Myrtales consisting of Combretaceae, Crypteroniaceae, Lythraceae, Melastomataceae sensu lato, Myrtaceae (including Psiloxylaceae3 and Heteropyxidaceae; Schmid, 1980), Oliniaceae, Onagraceae, Penaeaceae, Punicaceae, Sonneratiaceae, and Trapaceae (familial arrangement strictly alphabetical; see also Tobe & Raven, 1983a). The following embryological traits unite core Myrtales: anthers tetrasporangiate*, with conspicuous endothecium*, glandular tapetum, simultaneous cytokinesis; ovules anatropous*, bitegmic*, crassinucellate; antipodals ephemeral or absent*; endosperm nuclear*; seeds exalbuminous*. The asterisks indicate that exceptions are known. Table 1 (pp. 834-835) lists such exceptions, which in some cases are known for only one family or even only one species, for example, the trisporangiate anther of Corynanthera flava of Myrtaceae (Green, 1979). Other embryological features such as nuclear condition of pollen at time of shedding, persistence of anther epidermis, and types of anther wall development, embryo sac, and embryogeny vary appreciably (see Table 1). Significantly, Dahlgren and Thorne (1984) and Tobe and Raven (1983a) independently arrived at a very similar complex of embryological characters unifying core Myrtales. Reproductive anatomy, that is, histology and vasculature, gives no special aid in resolving the makeup of Myrtales. Features such as bicollateral bundles (internal or intraxylary phloem) occur in peduncles, inflorescence axes, pedicels, flowers, and fruits of most myrtalean taxa (Schmid, 1972b, 1980, for Myrtaceae and Lythraceae; Schmid, unpubl. data and literature survey for other families). However, bicollateral bundles are really histological markers first described for vegetative parts of Myrtales and other orders (Cronquist, 1981; Dahlgren & Thorn, 1984; Metcalfe & Chalk, 1983; van Vliet & Baas, 1984) and then applied to their reproductive parts. The same pertains to vestured pits, which are unreported for myrtalean reproductive structures, but which occur in Lythraceae, Melastomataceae, Myrtaceae, Alzatea (Schmid, unpubl. data). In Myrtales, amphicribral bundles are common, especially in androecia and placentae (Schmid, 1972b, 1980, for Myrtaceae and Lythraceae; Schmid, unpubl. data and literature survey for other families). However, amphicribral bundles seem related to functional, nutritional factors for reasons elaborated elsewhere (Schmid, 1976, 1978). There are no unifying features of floral vasculature for Myrtales (nor for other orders), let alone Myrtaceae. An axile ovular supply (Schmid, 1972a) is most common and clearly basic; the derived transeptal ovular supply (Schmid, 1972a) occurs variously in Myrtaceae, Oliniaceae, Onagraceae, Punicaceae, and Rhynchocalyx of core Myrtales (Eyde, 1981; Schmid, 1972a, 1972b, 1980, unpubl. data and literature survey), as well as in Lecythidaceae sensu lato, Rhizophoraceae

Wood Anatomy and Classification of the Myrtales

The wood anatomical diversity of the woody Myrtales, comprising Combretaceae, Lythraceae (including Alzatea), Melastomataceae (including Crypteroniaceae), Myrtaceae, Oliniaceae, Onagraceae, Penaeaceae, Punicaceae (can also be included in Lythraceae), Psiloxylaceae, Sonneratiaceae and also Thymelaeaceae, is summarized. All these families share intraxylary phloem and vestured pits, and their other wood anatomical attributes represent parts of continuous, sometimes divergent, often parallel, specialization series. Rhizophoraceae, Lecythidaceae, Elatinaceae, Cordiaceae, Chrysobalanaceae and Dialypetalanthaceae are excluded because they lack this combination of characters. The phylogenetic relationships within Myrtales are discussed, and pictured in a two-dimensional diagram (Figs. 2-8). Most families are mutually closely related. The wider wood anatomical affinities of the order are with Gentianales. Features from vegetative anatomy such as bicollateral bundles and vestured pits in the wood have entered discussions on the delimitation and classification of the order Myrtales for a long time. In this paper the entire evidence from wood anatomy will be applied to these taxonomic aspects. The knowledge of the wood anatomy of truly or putatively Myrtalean families has considerably increased in recent years (see references cited under the summarized wood anatomical descriptions) so that a discussion of its taxonomic implications can be meaningful. Our paper cannot, unfortunately, take wholly herbaceous families such as Haloragaceae and Trapaceae into consideration. For a survey of all families that have, from time to time, been assigned to the order Myrtales, the reader is referred to Dahlgren and Thorne (1984). DELIMITATION OF THE ORDER MYRTALES All families that have been and are currently regarded as indubitable members of the Myrtales are characterized by a combination of two anatomical features: vestures in the bordered pits of the secondary xylem, and bicollateral bundles in the primary stems (and leaves as far as major bundles are concerned), resulting in the presence of intraxylary or internal phloem in woody stems (not to be confused with interxylary or included phloem, which occurs in a restricted number of genera and families of the order only). Several authors have also used one or both of these characters in their delimitation of the order. Vestured pits and intraxylary phloem are rather uncommon in the Dicotyledons, as can be seen in Figure 1, where the distribution of these characters is illustrated using Dahlgren's (1980) diagrammatic classification. The data are derived from Metcalfe and Chalk (1950), completed for recent records of vestured pits by Meylan and Butterfield (1974), Miller (1977), and Baas and Werker (1981). The combined occurrence of vestured pits and intraxylary phloem appears to be very rare. Outside the Myrtales both features are found only in part of the Gentianiflorae (Apocynaceae, Asclepiadaceae, Loganiaceae pro parte) and in the Thymelaeales (Thymelaeaceae only) of Dahlgren's Malviflorae where the two characters are further only of very sporadic occurrence in the Euphorbiaceae, and then not even simultaneously present in the same genera (Bailey, 1933; Metcalfe & Chalk, 1950). Other combined occurrences are limited to Vochysiaceae (Polygalales) and the single genus Centropodium of the Polygonaceae (Polygonales). The sporadic occurrence of the two features outside the Myrtales as understood by us and Dahlgren and Thorne (1984), and their very conI Prof. Dr. C. Kalkman critically read the manuscript. Mr. J. van Os prepared the drawings. In connection with the research project on the wood anatomy of the Myrtales, concluded with this paper, the first author was over the years 1975-1977 financially supported by the Netherlands Organisation for the Advancement of Pure Research (Z.W.O.). 2 Hortus Botanicus, Nonnensteeg 3, 2311 VJ Leiden, The Netherlands. 3Rijksherbarium, P.O. Box 9514, 2300 RA Leiden, The Netherlands. ANN. MISSOURI BOT. GARD. 71: 783-800. 1984. This content downloaded from 157.55.39.111 on Tue, 02 Aug 2016 05:59:05 UTC All use subject to http://about.jstor.org/terms 784 ANNALS OF THE MISSOURI BOTANICAL GARDEN [VOL. 71 CARYOPHYLLIFLORAE 4 PROTE IFPLORAE POLYGONI FLORAEIFOA q L R R A E~~~~~~~~~~~~RIL/ A

COMPARATIVE ANATOMY AND MORPHOLOGY OF PS1LOXYLON AND HETEROPYXIS, AND THE SUBFAMILIAL AND TRIBAL CLASSIFICATION OF MYRTACEAE

SummaryEvidence from wood, leaf, and floral anatomy, from palynology, and from reconsideration of vegetative and reproductive morphology fully support (1) the placement of Heteropyxis by Fernandes (1971), Stern & Brizicky (1958), and Weberling (1963) in Myrtaceae/Leptospermoideae on the basis of organography, palynology, and petiole and wood anatomy, and (2) the placement of Psiloxylon by van Tieghem (1904) in Myrtaceae on the basis of especially vegetative anatomy. Diagnostic myrtaceous characters shared by both genera include: entire, simple, gland‐dotted, penninerved leaves wth intramarginal veins; rudimentary stipules (Heteropyxis only); pentamery; nectary lining floral tube; imbricate, persistent calyx; many pollen features; sunken styles; baccate or capsular fruits (resp. Psiloxylon and Heteropyxis); exalbuminous seeds; bicollateral bundles; secretory cavities in all aerial organs, including the anthers; unilacunar one‐trace nodes; arcuate petiolar bundles with sclerenchymatous sheaths (only in lamina of Psiloxylon); vestured pits; wood fibers with distinctly bordered pits; and tannin. Both genera, however, differ from many, but not all Myrtaceae in having: alternate leaves; unisexual, but bisexual‐appearing flowers (only the staminate in Psiloxylon); perigyny; few stamens (Psiloxylon diplostemonous, Heteropyxis essentially obdiplostemonous); short style and divided stigma (Psiloxylon only); cancellate seed (Psiloxylon only); and such wood characters as septate, crystalliferous fibers and lack of vasicentric tracheids in Psiloxylon, and lack of axial parenchyma in Heteropyxis. The segregates Heteropyxidaceae and Psiloxylaceae should thus be included in Myrtaceae. The foregoing ensemble of characters conclusively excludes for Heteropyxis any assignment to Rhamnaceae or Rutaceae, for Psiloxylon any assignment to Bixaceae sensu lato, Flacourtiaceae, or Guttiferae, and for both genera an assignment to Lythraceae. Because it would be anomalous in either of the two traditional myrtaceous subfamilies, Psiloxylon is best treated as a new subfamily in Myrtaceae. Finally, since Leptospermeae and Chamaelaucieae differ as much from each other as either does from Myrteae, Chamaelaucieae should be elevated to subfamilial status in Myrtaceae. The family Myrtaceae thus has four subfamilies: Myrtoideae, Psiloxyloideae, Leptospermoideae, and Chamaelaucioideae. An addendum discusses Briggs & Johnson's (1979) detailed paper on vegetative and especially reproductive structure of Myrtaceae.

Microautoradiography as a Tool for the Recognition of Phloem Transport

AbstractDuring the past twenty years, reports in literature have indicated the increasing use of autoradiographic techniques in problems dealing with translocation of nutrients in the phloem. Now the patterns of movement of photosynthates in plants with collateral or bicollateral bundles are fairly well known. But this technique can still bring us a far better knowledge of other aspects of phloem physiology, such as mechanism of phloem loading for instance.