Origem dos câmbios sucessivos em caule de três espécies de Menispermaceae

The lianas observed in this study, Abuta convexa (Vell.) Diels, Abuta imene (Mart.) Eichler, and Chondrodendron platiphyllum (A. St.-Hil.) Miers, all have successive cambia in their stems. The terminology applied to stem histology in species with successive cambia is as diverse as the interpretations of the origins of this cambial variant. Therefore, this study specifically investigates the origin of successive cambia through a developmental analysis of the above-mentioned species, including an analysis of the terminology used to describe this cambial variation. For the first time, we have identified several developmental stages giving rise to the origins of successive cambia in this family. First, the pericycle originates in 1-3 layers of conjunctive tissue. After the differentiation of the first ring, the conjunctive tissue undergoes new divisions, developing approximately 10 rows of parenchyma cells. In the middle portion, a layer of sclereids is formed, again subdividing the conjunctive tissue into two parts: internal and external. New cambia originate in the internal part, from which new secondary vascular strands will originate, giving rise to the second successive vascular ring of the stem. The external part remains parenchymatous during the installation of the second ring and will undergo new periclinal division, repeating the entire process. New cambia will originate from the neoformed strands, which will form only rays. In the literature, successive cambia are formed by a meristem called "diffuse lateral meristem."However, based on the species of Menispermaceae studied in this report, it is demonstrated that the diffuse lateral meristem is the pericycle itself.As lianas observadas neste estudo, Abuta convexa (Vell.) Diels, Abuta imene (Mart.) Eichler e Chondrodendron platiphyllum (A. St.-Hil.) Miers, possuem câmbios sucessivos em seus caules. A terminologia aplicada à histologia de caules de espécies com câmbios sucessivos é tão diversa quanto as interpretações das origens dessa variação cambial. O objetivo deste estudo é investigar a origem dos câmbios sucessivos através de uma análise do desenvolvimento nas espécies supracitadas, incluindo uma análise da terminologia utilizada para descrevê-los. Diversos estágios do desenvolvimento que originam os câmbios sucessivos em Menispermaceae foram constatados. Inicialmente, o periciclo forma de 1 a 3 camadas de tecido conjuntivo. Depois da diferenciação do primeiro anel, o tecido conjuntivo divide-se novamente, desenvolvendo cerca de 10 fileiras de células parenquimáticas. Na porção mediana forma-se um anel de esclereídes, subdividindo o tecido conjuntivo em duas partes. A parte mais interna (tecido conjuntivo interno) forma novos câmbios, que, por sua vez, originam os novos cordões vasculares secundários, formando, assim, o segundo anel vascular sucessivo do caule. A parte mais externa (tecido conjuntivo externo) permanece parenquimática durante a instalação do segundo anel e posteriormente sofrerá novas divisões periclinais, repetindo todo o processo descrito. Entre os cordões neoformados diferenciam-se novos câmbios que produzem somente raios. Conforme a literatura especializada, os câmbios sucessivos são formados por um meristema denominado "meristema lateral difuso". Neste estudo, é demonstrado que nas espécies analisadas o "meristema lateral difuso"é o próprio periciclo.Petrobras - Programa Mata Atlântic

Wood anatomy of major Bignoniaceae clades

The circumscription of Bignoniaceae genera and tribes has undergone major changes following an increased understanding of phylogenetic relationships within the family. While DNA sequence data have repeatedly reconstructed major clades within the family, some of the clades recovered still lack diagnostic morpho-anatomical features, complicating their recognition. In this study we investigated the wood anatomy of all major lineages of Bignoniaceae (except Tourrettieae) in search for anatomical synapomorphies for clades. We sampled 158 species of Bignoniaceae, representing 67 out of the 82 genera currently recognized. Detailed descriptions of quantitative and qualitative wood anatomical features are presented for each clade and interpreted in the light of a molecular phylogeny for the family. Jacarandae are characterized by a paratracheal winged-aliform parenchyma, with the traditional subdivision of Jacaranda into sections Monolobos and Dilobos supported by the uniseriate and homocellular rays of Monolobos versus the wide and heterocellular rays of Dilobos. Tecomeae s.s. are characterized by scanty paratracheal parenchyma, septate fibers, and heterocellular rays, traits also found in Delostoma, a genus previously included in Tecomeae s.l., but recently shown to represent a separate lineage. Crescentiina includes two sub-clades, the Tabebuia alliance and the Paleotropical clade, which share abundant aliform parenchyma, short and mainly homocellular rays, less commonly with heterocellular rays with body procumbent and one row of marginal square cells. Members of the Tabebuia alliance and the Paleotropical clade can be distinguished from each other by the narrow vessels with a widespread storied structure found in members of the Tabebuia alliance, versus the vessels with medium to wide width and a non-storied structure found in members of the Paleotropical clade. Oroxyleae are characterized by a combination of simple and foraminate perforation plates and homocellular rays, while Catalpeae are characterized by scanty paratracheal parenchyma, abundant tyloses and vessel-ray pits simple to semi-bordered. Bignonieae differ from all other clades by a variant secondary growth and a typically lianoid wood anatomy. Overall, wood anatomical characters are not very labile within the family, being distributed across clades in a very predictive manner. Several anatomical characters represent good anatomical synapomorphies and provide further support to clades identified in molecular phylogenetic studies.The authors are indebted to Alex C. Wiedenhoeft, Mike Wiemann and Regis Miller from the Forest Products Laboratory for warmly hosting us and allowing the study of the entire MADw collection (Madison, Wisconsin); Maria José Miranda and Raphael Pigozzo from the Institute of Technological Research (IPT, BCTw, São Paulo) for slides of Sparattosperma, Handroanthus and Tabebuia; Alexandre Zuntini, Anselmo Nogueira, Diana Sampaio, Mariane Souza-Baena, Milton Groppo from the Universidade de São Paulo (Brazil), Márdel Lopes from the Universidade Federal de Viçosa (Brazil), and Luzmilla Arroyo and Daniel Villaboel of the Museo Noel Kempff Mercado (Bolivia) for collecting samples or for assistance in field collections, Harri Lorenzi for allowing us to collect samples at the Instituto Plantarum/Jardim Botânico Plantarum; Antonio Carlos Franco Barbosa sectioning Stereospermum; Julio C. Majcher for sectioning samples of Oroxyleae used in Scanning Electron Microscopy; Pieter Baas, Michelle Zjhra, Guillermo Angeles, and Giuliano Locosselli for invaluable suggestions in early versions of the manuscript; Gabriella Pace, Lizana Rezende and Carolina L. Bastos for valuable support, the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, grants 481034/2007-2; 486971/2012-0), and the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP, grant 2012/01099-8; 2013/10679-0) for financial support. RGO is supported by US National Science Foundation (DEB-0309065, DEB-1353761). LGL and VA by CNPq productivity 307781/2013-5 and 308441/2012-5, respectively

Anatomie de l’écorce des Bignoniaceae lianescentes : synopsis générique

La moitié des Bignoniaceae sont des espèces à port lianescent. Des travaux récents ont proposé de nouveaux découpages dans les groupes entièrement lianescents, notamment pour les tribus des Bignonieae et des Tecomeae s.s. Nus avons ici rassemblé, sectionné et analysé les tiges de 83 Bignoniaceae grimpantes, comprenant tous les genres de Bignonieae et trois autres de Tecomeae s.s. largement cultivées, afin de trouver des caractères d’intérêt taxonomique permettant de décrire précisément la diversité anatomique de leurs écorces, en rapport avec les dernières phylogénies. Nous avons pu reconnaître 19 synapomorphies potentielles de la tige et de l’écorce à l’échelle de clades ou de genres lianescents, telles que – entre autres – le phloème fibreux des Fridericia Mart. emend L.G.Lohmann et alliés, la présence exclusive de sclérites dans le phloème régulier de Pleonotoma Miers, ainsi que de fibres étirées radialement chez Manaosella J.C.Gomes. La combinaison de ces caractères nous a permis de construire une première clé d’identification des écorces pour la détermination générique des Bignoniaceae lianescentes, même en l’absence de toute autre donnée morphologique. Nos résultats confirment l’importance de l’anatomie de l’écorce dans la compréhension de la taxonomie et de la phylogénie, et donc de la diversification.Species with lianescent habit account for half of the diversity of Bignoniaceae. Recent molecular phylogenetic studies have provided the basis for new circumscriptions of entire liana lineages within tribes Bignonieae and Tecomeae s.s., where only monophyletic taxa are recognized. However, some clades remain without good morphological synapomorphies. In search of features of taxonomic potential, we collected, sectioned, and analyzed the bark of 83 lianescent species of the Bignoniaceae, covering all 20 genera from tribe Bignonieae currently recognized, plus three of the most widely cultivated lianas of Tecomeae s.s. Detailed bark descriptions are given to major lineages within both tribes, following their most recent phylogenetic hypotheses and classifications. Our anatomical studies allowed us to identify 19 potential synapomorphies for large clades or specific genera of lianas, such as the fibrous phloem found in members of the Fridericia Mart. emend L.G.Lohmann and allies clade, the exclusive presence of sclereids in the regular phloem of Pleonotoma Miers, and the presence of radially elongated fibers in Manaosella J.C.Gomes, among others. Using a combination of features, we were able to produce the first bark key to identify genera of lianescent Bignoniaceae. Our work reinforces the importance of bark features for a deeper understanding of taxonomic and phylogenetic relationships among taxa.</p

Anatomy of Brazilian Cereeae (subfamily Cactoideae, Cactaceae): Arrojadoa Britton &amp; Rose, Stephanocereus A. Berger and Brasilicereus Backeberg

(Anatomy of Brazilian Cereeae (subfamily Cactoideae, Cactaceae): Arrojadoa Britton &amp; Rose, Stephanocereus A. Berger wâBrasilicereus Backeberg). Arrojadoa, Stephanocereus and Brasilicereus are endemic Brazilian Cereeae, occurring along the Espinhaço Range, in the campos rupestres, cerrados and caatingas, from northern Minas Gerais to southern Bahia. The genera are columnar, erect to semi-erect cacti, except for one species, A bahiensis, which is globose. This study describes the anatomy of dermal, fundamental and vascular systems, aiming to find diagnostic characters for the genera and species. Basal portions of stems were sectioned transversely and longitudinally, and stained with Astrablue and Safranin. The species share a uniseriate epidermis, with thick cuticle; well developed collenchymatic hypodermis, containing prismatic crystals; cortex with numerous mucilage cells, druses and vascular bundles; outside cortex as a palisade parenchyma; periderm composed of lignified cork cells alternating with suberized cells; pheloderm consisting of a few layers of thin-walled cells; phloem composed of solitary or multiple of two to three sieve tube elements, companion cells, axial and radial parenchyma; secondary xylem with solitary to multiple vessels, with simple perforation plates and alternate bordered to semi-bordered pits; axial parenchyma scanty vasicentric to incomplete; libriform septate fibres; large rays. Unlignified parenchyma is seen in the secondary xylem, varying from a few cells to bands among axial and radial elements. The following are considered diagnostic characters: the shape of lignified phellem cells, cubic to radially elongate, which individualizes S. leucostele; an underdeveloped hypodermis and the occurrence of sclereids in the cortex are exclusive to Brasilicereus markgrqfii

Variação cambial em Serjania caracasana (Sapindaceae): enfoque na adequação terminológica

RESUMO O corpus lignosum compositum, típico para as lianas da família Sapindaceae, é designado neste trabalho como "cilindro vascular composto". No caule de Serjania caracasana (Jacq.) Willd. essa variação cambial está representada por um cilindro vascular central circundado por oito cilindros vasculares periféricos. Não existe consenso quanto à terminologia que envolve essa estrutura, o que torna difícil uma abordagem anatômica desagregada de uma adequação terminológica. Nesse estudo, por meio da análise anatômica do caule, verificou-se que mesmo antes da vascularização há indícios do aspecto composto, com a formação de oito lobos que circundam a região central. Com o início da vascularização, cada lobo e a região central são denominados "cilindro vascular". O termo aqui adotado "cilindro vascular composto" é adequado, pois reflete a homologia entre os cilindros vasculares em S. caracasana através da origem procambial. Esse termo exibe um caráter descritivo que facilita a compreensão do conceito e mantém a relação de equivalência lingüística com o termo original - corpus lignosum compositum. Rejeita-se o termo "caule poliestélico" ou "caule multiestelar", pois os resultados aqui apresentados indicam a presença de um único estelo no caule

INCREASED WATER STORAGE CAPACITY IN CACTUS WOOD: A STUDY IN THE TRIBE CEREEAE (CACTOIDEAE, CACTACEAE)

Secondary xylem of fibrous cactus wood is characterized by short narrow vessel elements with both simple perforation plates and large intervessel pits, libriform septate fibers, and large rays. These are present in basal cactus taxa, as well as in many other groups of the family. In Cactoideae, the most diversified and most derived subfamily, there are remarkable variations found in the secondary xylem, with the more highly derived taxa containing the greatest water storage capacity. Unlignified parenchyma is one specialization found in the fibrous wood of cacti. We observed this tissue in the secondary xylem at the base of the sterns of several Brazilian endemic species of Arrojadoa, Melocactus, and Stephanocereus, all members of the tribe Cereeae. In Arrojadoa and Melocactus the unlignified parenchyma occurs in lines and bands amongst the axial and radial xylem elements, while in Stephanocereus it is mainly restricted to the rays and does not form bands. We address the adaptive importance of the unlignified parenchyma in the fibrous wood in tribe Cereeae and the family Cactaceae as a whole.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)[98/15102-1]Conselho Nacional de Desenvolvimento Cientifico e Tecnologico-CNPqConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Is the secondary thickening in palms always diffuse?

Unlike other arboreal monocotyledons, the secondary growth of palms has for the past 100 years been described as diffuse. Solely cell enlargement and random parenchyma divisions, without the activity of a meristem, characterize such growth. Some previous works of the early 20th century have, however, mentioned the presence of a secondary meristem in the stems of palms, but this information was forgotten since then. Addressing to this question, we analysed palm stems of four species, with the aim to understand the possible presence of such secondary growth. We found that a meristematic band occurs between the cortex and the central cylinder and gives rise to new vascular bundles and parenchyma internally, producing parenchyma and fibres externally. It appears secondarily, i.e., it undergoes meristematic activity in the median and basal stem regions, far away from the apical region. In fact, a meristematic band is present and may be more common than currently believed, but uneasy to detect in certain palms for being restricted to specific regions of their stems. In conclusion, the diffuse secondary thickening is here shown not to be the only mechanism of secondary growth in palms. The presence of a meristem band in the stems of palms merits careful reconsideration