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Um Novo e Peculiar Tipo de Sistema Subterrâneo em Espécies de Vernonia da Serra do Cipó (Minas Gerais, Brasil)
Abstract
Descreve-se um novo tipo de caule subterrâneo que ocorre em especies de Vernonia da Serra do Cipo (Minas Gerais, Brasil), que tem a peculiaridade de apresentar crescimento geotropico positivo, gemas laterais e um notavel numero de raizes adventiceas. Em analogia com o que ocorre em Selaginella, sugere-se o nome rizoforo para essa estrutura. Em condicoes naturais, no solo, suas gemas laterais dao sempre origem a novos rizoforos.
... Andreata & Menezes (1999), fundamentadas nas características estruturais do órgão e em seu desenvolvimento, assim como em estudos anteriores sobre o gênero Vernonia Screb. (Menezes et al. 1979;Sajo & Menezes 1986;Rocha & Menezes 1997), propuseram estender a designação de "rizóforo" ao órgão homólogo de Smilax quinquenervia Vell. ...
... Esse termo foi indicado por Menezes et al. (1979), ao reinterpretarem o sistema subterrâneo de Vernonia psilophylla DC. e V. linearifolia Less. (Asteraceae). ...
... O caule subterrâneo das espécies de Smilax tem sido designado na literatura especializada ora como rizóforo (Cunha 1937;Oliveira et al. 1973;Guaglianone & Gattuso 1991;Palhares & Silveira 2005;Silva 2006), ora como rizoma (Andreata & Menezes 1999;Martins & Appezzato-da-Glória 2006), com base, principalmente, nos aspectos morfológicos. Menezes et al. (1979), Sajo & Menezes (1986), Rocha & Menezes (1997) e Andreata & Menezes (1999), analisando estruturas subterrâneas similares aos rizomas, que se distinguiam destes por apresentarem sistema bipolar de ramificação caulinar, adotaram uma nova interpretação para tais estruturas. Andreata & Menezes (1999), acompanhando a ontogenia de Smilax quinquenervia, verificaram que o sistema subterrâneo desta espécie apresenta características de rizóforo, adotando assim este termo para desginá-la. ...
Resumo Smilax subsessiliflora Duhamel, espécie exclusivamente brasileira, tem por habitat a floresta Atlântica, mesófila e as matas de restinga. Este trabalho tem por objetivo descrever a morfoanatomia do sistema subterrâneo de S. subsessiliflora. O sistema subterrâneo da espécie em questão é constituído pelo rizóforo, do qual partem os ramos caulinares e as raízes adventícias. O rizóforo apresenta epiderme uniestratificada com estômatos, córtex com células de paredes espessadas e lignificadas, meristema de espessamento primário e cilindro vascular, integrado por feixes colaterais. Das raízes adventícias que partem do rizóforo originam-se outras que se distinguem pelo calibre e pela cor. Aquelas apresentam córtex externo, constituído por células parenquimáticas e córtex interno, constituído por esclereídes, que passam a exercer a função de revestimento, após a eliminação do córtex externo. O cilindro vascular é poliarco e sifonostélico. Grãos de amido ocorrem no periciclo e na medula. No córtex das raízes laterais detectaram-se endomicorrizas arbusculares. As características anatômicas observadas no sistema subterrâneo de S. subsessiliflora se assemelham às relatadas para o rizóforo de S. quinquenervia.
... The occurrence of thickened underground systems in Asteraceae is widely reported in the literature, including xylopodia, rhizophores, tuberous roots, diffuse underground systems and rhizomes (Paviani 1977, 1978, 1987, Menezes et al. 1979, Sajo and Menezes 1986, Lotocka and Geszprych 2004, Machado et al. 2004, Hayashi and Appezzato-da-Glória 2005, 2007, Vilhalva and Appezzato-da-Glória 2006a, b, Appezzatoda-Glória et al. 2008a, b, Cury and Appezzato-da-Glória 2009, Appezzato-da-Glória and Cury 2011, Vilhalva et al. 2011, Bombo et al. 2014. Many Asteraceae species have fructans in the thickened underground systems (Tertuliano and Figueiredo-Ribeiro 1993). ...
... The underground system of Chrysolaena simplex was a rhizophore. This term was used for the first time in Asteraceae by Menezes et al. (1979) to refer to a new and peculiar type of subterranean stem system in species of Vernonia from campos rupestres in Serra do Cipó. These authors have proposed the term rhizophore in analogy to the organ with roots present in Selaginella. ...
... In Brazil, after the precursor work by Menezes et al. (1979), rhizophores were also described for other species in Asteraceae (Sajo and Menezes 1986, Melo-de-Pinna and Menezes 2002, Machado et al. 2004, Hayashi and Appezzato-da-Glória 2005, Appezzato-da-Gloria et al. 2012, Dioscoreaceae (Rocha and Menezes 1997), Smilacaceae (Andreatta and Menezes 1999, Martins andAppezzato-da-Glória 2006) and Rhizophoraceae (Menezes 2006). ...
A presença de sistemas subterrâneos espessados em Asteraceae tem sido amplamente relatada na literatura. Devido à grande complexidade dos sistemas subterrâneos, que podem ser de natureza radicular, caulinar ou mista, as análises morfoanatômicas são importantes para assegurar a utilização da terminologia correta. Este estudo teve por objetivo descrever a morfoanatomia e ontogenia, investigar a presença de metabólitos secundários e avaliar os efeitos da sazonalidade no sistema subterrâneo de Chrysolaena simplex (Less.) Dematt. As amostras foram estudadas usando os protocolos padrão de anatomia vegetal, eletrônica de varredura, histoquímica e fitoquímica. O sistema subterrâneo de C. simplex foi identificado como rizóforo, que se originou do nó cotiledonar. Em indivíduos adultos, com rizóforos completamente desenvolvidos, as raízes primárias degeneram e formam sistemas radiculares adventícios. As gemas, nas porções subterrâneas, promovem o crescimento do rizóforo e formaram caules aéreos quando expostas à luz. Gotas lipofílicas foram evidenciadas nas células parenquimáticas do córtex e medula, endoderme e gemas. Frutanos tipo inulina foram evidenciados no eixo caulinar e gemas do rizóforo. A ocorrência de gemas, metabólitos secundários, frutanos e lipídeos armazenados no rizóforo, podem ser apontados como caracteres adaptativos.
... However, there was a system formed by the aerial stem originating from the plumule and the primary root and lateral ramifications originating from the radicle, as well as buds formed on the hypocotyl giving rise to underground and aerial stem branches. A bipolar stem branching system, which in this case forms an aerial system from the embryo's plumule and an underground system from hypocotyl buds, was first described by Menezes et al. (1979) in species of Vernonia Schreb (Asteraceae) from Serra do Cipó (Minas Gerais, Brazil). After this work, Andreata (1997) and Andreata & Menezes (1999) also adopted the term rhizophore for Smilax Vell. ...
Stigmaphyllon blanchetii is a perennial climbing species native to Brazil, mainly in the Northeast region, usually in sugarcane fields. Considered a weed, it presents aggressive reproduction and invasive behavior and can colonize sugarcane crops through stem and branch sprouts, resulting in several gaps at the beginning of planting and reducing the productivity of harvesting machines. However, the mechanism behind its invasive behavior, in which vegetative propagation through the underground organ plays an important role, is known. The objective of this work was to analyze whether the underground organ of S. blanchetii contributes to the rapid vegetative propagation of this species and define its structural origin and terminology through morpho-anatomical analyses. Morphological analyses were performed with the naked eye and under a stereomicroscope, and the structures were schematized and documented by means of images captured with a digital camera and illustrations. Anatomical analyses were performed using material fixed in FAA 70 and preserved in 70% alcohol. Histochemical tests were also performed. The results revealed that the underground structure is a complex and diffuse system composed of aerial stems, underground stems and three types of roots: primary, lateral, and adventitious. Due to the bipolar stem branching pattern, with aerial and underground branching, the underground structure of S. blanchetii was recognized here as a rhizophore and, through bud formation on hypocotyls and underground stems, it effectively participates in the vegetative propagation of the species.
... Vernonia herbacea (Vell.) Rusby stands out for accumulating about 80% fructan on a dry mass basis (Carvalho and Dietrich 1993) in the reserve organ, known as rhizophore (Menezes et al. 1979;Hayashi and Appezzato-da-Glória 2005). V. herbacea (Fig. 4) is a perennial herb that shows a marked phenological behavior consistent with the seasonality of the cerrado vegetation and the climate characteristics of this habitat. ...
... As campos rupestres are fire-prone environments within the cerrado (Simon et al. 2009), underground storage tissues allow resprouting after fire (Joaquim et al. 2014) as well as after prolonged drought (Garcia et al. 2011), although the development of these structures is usually not so marked as in cerrado soils (see Sect. 11.2.1). Despite the body of literature on the underground anatomy of campos rupestres families like Asteraceae, Xyridaceae and Eriocaulaceae (Pillai and Pillai 1961;Menezes et al. 1979;Scatena et al. 2005), little is known about the nutrient-acquisition strategies of these root structures and what exactly is stored in these structures . ...
Campos rupestres are rocky seasonally-dry environments that occur over mountaintops in central Brazil. Plant growth is limited and prone to fire during the dry winter, and soils are severely nutrient-impoverished. Plants in these habitats exhibit a wide range of strategies to cope with these limitations. Campos rupestres plants show different rooting depths, according to plant habit and substrate. Water status in plants varies between stable water potentials in isohydric species to water potentials changing according to air humidity in anisohydric plants, some of them being dessication-tolerant and dormant during the dry season (resurrection plants). Carbon assimilation in the dry season is therefore limited by water availability, especially in dessication-tolerant species. A wide variety of mineral nutrition strategies allow effective nutrient acquisition in campos rupestres: mycorrhizas, non-mycorrhizal sand-binding root specializations, symbiotic nitrogen fixation, carnivory, parasitism. The incidence of natural fires may have played a role in the ecological and evolutionary processes that have molded the current flora of campos rupestres, as well as the occurrence of specific functional traits in these habitats. Unveiling the relative importance and prevalence of in situ adaptation and adaptive divergence in the lineages that diversified in campos rupestres will allow us to further discuss mechanisms related to trait evolution and adaptive radiation in campos rupestres.
... E assim, como em outras formações vegetais, como caatinga e savana, as plantas acabaram por desenvolver órgãos especializados em reserva, seja de água ou nutrientes, para viabilizarem sua própria sobrevivência. Desta forma, nestas situações, ocorrem com certa frequência, os sistemas subterrâneos espessados [9]. ...
Question
How does seasonality affect the below‐ground bud bank dynamics in open savannas from the Cerrado and the density of below‐ground bud‐bearing organs? As the Cerrado is subject to marked seasonality, many herbaceous plants may lose their above‐ground biomass during the dry season, and regenerate it later in the rainy period through resprouting from below‐ground buds. Herein, we tested the hypothesis that seasonality may directly affect bud bank dynamics and below‐ground bud‐bearing organs, with a larger bud bank size and higher densities of below‐ground organs in the rainy season.
Location
Open savannas of the Cerrado, southeastern Brazil.
Methods
The bud bank was sampled in three open areas of the Cerrado. In each area, 10 plots were established, and, within each plot, the biomass was sampled to 10 cm below‐ground level. In the lab, buds and below‐ground organs were counted. We fitted generalized linear mixed models (GLMM) to test the differences in the bud bank and the below‐ground organ densities between the dry and rainy seasons.
Results
The bud bank size was smaller in the dry season. Buds found in the dry season suggest they were developed in the rainy season and remained dormant, not forming new shoots. Non‐woody rhizomes of caespitose grasses were more abundant during the rainy season. Xylopodia and woody rhizome densities were not significantly affected by seasonality.
Conclusions
Bud bank dynamics in the Cerrado is affected by seasonality. There is a decrease in bud bank density in the dry season, suggesting that buds were developed into new branches in the rainy season, but not all of them develop into new shoots in the same season. Thus, the bud bank evaluated in the dry season probably is formed by an accumulation of dormant preformed buds, highlighting the occurrence of a resprouting dynamic of native species of the Cerrado in the rainy season.
Herbaceous plants collectively known as geophytes, which regrow from belowground buds, are distributed around the globe and throughout the land plant tree of life. The geophytic habit is an evolutionarily and ecologically important growth form in plants, permitting novel life history strategies, enabling the occupation of more seasonal climates, mediating interactions between plants and their water and nutrient resources, and influencing macroevolutionary patterns by enabling differential diversification and adaptation. These taxa are excellent study systems for understanding how convergence on a similar growth habit (i.e., geophytism) can occur via different morphological and developmental mechanisms. Despite the importance of belowground organs for characterizing whole‐plant morphological diversity, the morphology and evolution of these organs have been vastly understudied with most research focusing on only a few crop systems. Here, we clarify the terminology commonly used (and sometimes misused) to describe geophytes and their underground organs and highlight key evolutionary patterns of the belowground morphology of geophytic plants. Additionally, we advocate for increasing resources for geophyte research and implementing standardized ontological definitions of geophytic organs to improve our understanding of the factors controlling, promoting, and maintaining geophyte diversity.
Not all plant traits from all regions have been standardized or databased. Some ecosystems, such as tropical grasslands, are under-represented in such databases owing to the difficulty in assessing bud banks and evaluating clonal growth. This study aimed to (i) determine whether Brazilian morphological traits of belowground organs can be translated into categories used in the CLO-PLA database and (ii) assess the applicability of clonal and bud bank traits standardized in the CLO-PLA database for Brazilian Aldama species, which have specialized belowground organs and are able to resprout. In all, 165 species, including herbs, subshrubs and shrubs, of 37 genera from different Brazilian ecosystems, were evaluated. Not all the traditional Brazilian morphological categories could be translated into CLO-PLA traits, resulting in a lower number of categories and loss of information regarding plant morphology. Furthermore, clonal and bud bank traits could be only partially evaluated for Aldama, since some traits showed seasonal variation. The CLO-PLA classification focused on the organs in relation to the soil surface, the connection between mother and daughter shoots, and the origin of buds from which daughter shoots sprout. In the Brazilian classification, by contrast, anatomical features or early ontogeny of the organ are very important. Nevertheless, our results might form the basis for future comparative studies across ecosystems and biomes, for which common trait standardization is necessary. However, further research is needed to assess the functional morphology of clonal and bud bank traits in tropical regions.
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