Scielo RSS <![CDATA[Acta Botanica Brasilica]]> vol. 28 num. 2 lang. es <![CDATA[SciELO Logo]]> <![CDATA[<b>Expanding the description of <i>Bionia bella </i>Mart. ex Benth. (Leguminosae, Papilionoideae)</b>]]> Bionia bella Mart. ex Benth. (Leguminosae, Papilionoideae) is restricted to the Atlantic Forest Biome in the Brazilian states of Minas Gerais and Espírito Santo. The vegetative and floral structures of the species were first described by George Bentham in 1837. The objective of the present study was to describe, for the first time, the fruits and seeds of the species, thus complementing the type material. From 2006 through 2010, we observed four populations of the species in a forest fragment near Serra do Brigadeiro State Park, located in the municipality of Araponga, in the state of Minas Gerais. Two of the four populations fruited only in 2010, and the other two populations produced no fruit during the study period. The fruits of B. bella are of the legume type, with explosive dehiscence, as in other species of the genus. The seeds are broad-elliptical, and the testa presents rugose ornamentation. Bionia bella is a good candidate for reproductive biology studies aimed at understanding reproductive difficulties in such species. <![CDATA[<b>Polyphysaceae (Dasycladales, Chlorophyta) in Todos os Santos Bay, Bahia, Brazil</b>]]> In this paper, we summarize the diversity of Polyphysaceae species in Todos os Santos Bay, in the state of Bahia, Brazil. On the basis of ten years of collections and the analysis of herbarium material, six species have been recorded for the area: Acetabularia caliculus J.V.Lamour. in Quoy & Gaimard; A. crenulata J.V.Lamour.; A. schenckii Möbius; Parvocaulis myriosporus (Joly & Cord.-Mar.) C.W.N.Moura & J.C.De Andrade comb. nov.; P. pusillus (M.Howe) Berger et al.; and P. parvulus (Solms) S. Berger et al. The last has a distribution extending to the southern Atlantic Ocean. Acetabularia myriospora was transferred to Parvocaulis (as P. myriosporus) on the basis of its short corrugated peduncles and lack of a lower corona in the gametangial ray discs, which are diagnostic characters of this genus. In Todos os Santos Bay, Acetabularia species are more widely distributed than are Parvocaulis species, which are currently restricted to Itaparica Island. The most common taxa were A. caliculus and A. schenckii, which were collected from the majority of the study sites. This paper provides detailed descriptions of the morphology, reproductive aspects and geographic distributions of the algae, as well as discussing the taxa studied. <![CDATA[<b>Palynomorphs in Holocene sediments from a paleolagoon in the coastal plain of extreme southern Brazil</b>]]> This paper presents the results of a qualitative palynological analysis of a 140 cm-thick section of Holocene sediments from a paleolagoon, representing the last 2600 years, taken from an outcrop at Hermenegildo Beach (33º42'S; 53º18'W), located in the municipality of Santa Vitória do Palmar, in the state of Rio Grande do Sul, Brazil. Samples were treated with hydrochloric acid, hydrofluoric acid and potassium hydroxide, after which they were subjected to acetolysis and mounted on glycerin-coated slides for light microscopy analysis. Among the 48 palynomorphs identified were 25 fungi, eight algae, three bryophytes, and 12 pteridophytes. Brief descriptions and illustrations of each palynomorph are presented, together with ecological data from the organism of origin when possible. Our findings will serve as reference material for paleoenvironmental studies in the coastal plain of southern Brazil. <![CDATA[<b>First records of pollen rain in bromeliad tanks in an area of <i>caatinga</i> in northeastern Brazil</b>]]> Species of Bromeliaceae have leaves in a spiral configuration. Because of the shape of the rosette thus formed and the imbricate configuration of the leaf sheaths, there is usually a tank in which rainwater and other components of the environment, including pollen grains, accumulate, making such tanks effective pollen rain collectors. The objective of this study was to use bromeliads as a tool to increase knowledge about the vegetation of the caatinga (shrublands) in the Canudos region of the state of Bahia, located in the semi-arid zone of Brazil, as well as to analyze the dynamics of pollen dispersal and deposition. To that end, we collected samples of the water from the tanks of bromeliads at the Canudos Biological Station. A total of 149 pollen types were detected, 88 of which could be identified botanically. The families that were the most well-represented among the pollen types were Fabaceae (with 25), Asteraceae (with 9), and Euphorbiaceae (with 7). Ten pollen types were presented as potential indicators of caatinga vegetation. We conclude that tank bromeliads are useful for gathering information about pollen rain and pollen dynamics, as well as about the transport and deposition of pollen in the caatinga. <![CDATA[<b>An efficient system for <i>in vitro</i> propagation of <i>Bouchea fluminensis</i> (Vell.) Mold. (Verbenaceae)</b>]]> This study aimed to establish and propagate in vitro plants of Bouchea fluminensis, a medicinal species known in Brazil as gervão-falso ("false verbena"), evaluating the influences of different growth regulators on in vitro multiplication and rooting stages, as well as examining ex vitro acclimatization of rooted plants. Explants were established on Murashige and Skoog medium at half strength of salts and vitamins without growth regulators. For multiplication, the explants were subjected to combinations of 6-benzyladenine (BA; 0, 2.5, 5.0 and 7.5 µM) and α-naphthalene-acetic acid (NAA; 0, 0.2, 0.4 and 0.6 µM). The medium found to induce the greatest number of shoot was that containing 5 µM of BA (NAA-free). For rooting, we evaluated three auxins (NAA, indole-3-acetic acid and indole-3-butyric acid; 0.1, 0.2, 0.3 and 0.4 µM), as well as a control. No differences were observed between the control and the other treatments. The auxin-free medium was deemed the most suitable, because it ensures the lowest cost in the micropropagation procedures. We obtained 100% survival of the acclimatized seedlings, and the plants showed normal vegetative and reproductive development, suggesting that the micropropagation did not alter the biological cycle of this species. The results show the importance and potential of micropropagation for biodiversity conservation of Bouchea fluminensis. <![CDATA[<b>Tree community dynamics in a submontane forest in southeastern Brazil: growth, recruitment, mortality and changes in species composition over a seven-year period</b>]]> In order to assess long-term community dynamics in tree populations, we investigated trees with a diameter at breast height (DBH) > 5 cm in an 11-ha fragment of submontane tropical forest in southeastern Brazil, at the beginning and end of a seven-year period. We observed a general tendency toward decreasing numbers of trees and toward stability in basal area. The stability in basal area was associated with an equilibrium between the loss of trees and the basal area gain from the horizontal growth of surviving trees, as well as from recruits The abundance of dead trees was significantly higher than was that of recruits. Changes in tree abundance occurred mainly in the lower DBH classes, whereas changes in basal area occurred mainly in the intermediate DBH classes. Among trees with a DBH > 10 cm, the observed rates of mortality and recruitment (2.4% yr-1 and 1.8% yr-1, respectively) were similar to those reported for other tropical forests. When we examined only trees with a DBH > 10 cm, we found the half-life to be 29.5 years, which places the forest fragment studied among the most dynamic of tropical forests. Over the seven-year period evaluated, the tree community lost ten species, with no new records. The most abundant species showed the highest rates of mortality and recruitment. Climax species, whether shade-tolerant or light-demanding, accounted for more species and individuals than did pioneer species, suggesting that the former group has a greater influence on forest dynamics. The results suggest that the tree community studied is in or is approaching a state of dynamic equilibrium, the changes in community structure and composition being attributed to periodic fluctuations. <![CDATA[<b>Using AFLP-RGA markers to assess genetic diversity among pigeon pea (<i>Cajanus cajan</i>) genotypes in relation to major diseases</b>]]> Resistance gene analog (RGA)-anchored amplified fragment length polymorphism (AFLP-RGA) marker system was used in order to evaluate genetic relationships among 22 pigeon pea genotypes with varied responses to Fusarium wilt and sterility mosaic disease. Five AFLP-RGA primer combinations (E-CAG/wlrk-S, M-GTG/wlrk-S, M-GTG/wlrk-AS, E-CAT/S1-INV and E-CAG/wlrk-AS) produced 173 scorable fragments, of which 157 (90.7%) were polymorphic, with an average of 31.4 fragments per primer combination. The polymorphism rates obtained with the five primers were 83.3%, 92.0%, 92.3%, 93.0% and 93.1%, respectively. Mean polymorphic information content (PIC) values ranged from 0.24 (with E-CAT/S1-INV) to 0.30 (with E-CAG/wlrk-AS), whereas resolving power (RP) values varied from 11.06 (with M-GTG/wlrk-S) to 25.51 (with E-CAG/wlrk-AS) and marker index (MI) values ranged from 5.98 (with M-GTG/wlrk-S) to 12.30 (with E-CAG/wlrk-AS). We identified a positive correlation between MI and RP (r²=0.98, p<0.05), stronger that that observed for the comparison between PIC and RP (r²=0.88, p<0.05). That implies that either MI or RP is the best parameter for selecting more informative AFLP-RGA primer combinations. The Jaccard coefficient ranged from 0.07 to 0.72, suggesting a broad genetic base in the genotypes studied. A neighbor-joining tree, based on the unweighted pair group method with arithmetic mean, distinguished cultivated species from wild species. The grouping of resistant genotypes in different clusters would help in the selection of suitable donors for resistance breeding in pigeon pea. <![CDATA[<b>Subspecies of <i>Hypolepis rugosula</i> (Dennstaedtiaceae; Pteridophyta) around the world: morphological and biogeographic perspectives</b>]]> The "Hypolepis rugosula complex" has been the subject of great debate among pteridologists: some have considered H. rugosula a single subcosmopolitan (or circum-Antarctic) species, whereas others have considered it a species-complex, encompassing several species. In the 1920s and 1930s, four geographically distinct varietiesof H. rugosula were recognized. In this work, we present a new taxonomy (with new combinations and statuses, as well as typification and full synonymy), together with complete distribution data for the species, with an infraspecific classification based on morphological and biogeographic perspectives. Hypolepis rugosula occurs in southern temperate regions and high-elevation tropical regions of the Americas, Africa (including Madagascar), Oceania and the Philippines, as well as in some isolated oceanic volcanic islands (e.g., Saint Helena and Tristan da Cunha). Here, 15 geographically distinct subspecies are recognized. All subspecies are geographically segregated from each other, except in New Zealand, where two occur sympatrically-possibly due to two different arrival and colonization times. Four patterns of "indument" (referring to catenate and glandular hairs collectively) are distinguished. Different lineages are successful in their respective habitats; we observed two lineages with different ploidy levels (tetraploid and octoploid). Although long-distance dispersal is the best explanation for the extant distribution of H. rugosula;we do not exclude vicariance as a possible explanation for their occurrence on the land masses that were once united as Gondwana. Therefore, we are assuming that a fern species could remain unchanged for more than 70 Myr, and we are adopting the refugia theory, albeit with a different focus. <![CDATA[<b>Tree species composition in areas of Atlantic Forest in southeastern Brazil is consistent with a new system for classifying the vegetation of South America</b>]]> Rigorous and well-defined criteria for the classification of vegetation constitute a prerequisite for effective biodiversity conservation strategies. In 2009, a new classification system was proposed for vegetation types in extra-Andean tropical and subtropical South America. The new system expanded upon the criteria established in the existing Brazilian Institute of Geography and Statistics classification system. Here, we attempted to determine whether the tree species composition of the formations within the Atlantic Forest Biome of Brazil is consistent with this new classification system. We compiled floristic surveys of 394 sites in southeastern Brazil (between 15º and 25ºS; and between the Atlantic coast and 55ºW). To assess the floristic consistency of the vegetation types, we performed non-metric multidimensional scaling (NMDS) ordination analysis, followed by multifactorial ANOVA. The vegetation types, especially in terms of their thermal regimes, elevational belts and top-tier vegetation categories, were consistently discriminated in the first NMDS axis, and all assessed attributes showed at least one significant difference in the second axis. As was expected on the basis of the theoretical background, we found that tree species composition, in the areas of Atlantic Forest studied, was highly consistent with the new system of classification. Our findings not only help solidify the position of this new classification system but also contribute to expanding the knowledge of the patterns and underlying driving forces of the distribution of vegetation in the region. <![CDATA[<b>Mortality, recruitment and growth of the tree communities in three forest formations at the Panga Ecological Station over ten years (1997-2007)</b>]]> The area evaluated in this study was a continuous stretch comprising three vegetation formations: gallery forest, semideciduous seasonal forest and cerradão (woodland savanna). The aim of this study was to examine the tree community dynamics in a forest gradient-from gallery forest to cerradão-at Panga Ecological Station, in the city of Uberlandia, located in the state of Minas Gerais, Brazil. The study was based on data from a previous inventory of the continuous forest conducted in 211 permanent 10 × 10 m sample plots in eight parallel transect running perpendicular to Panga Creek. Trees with a diameter at breast height > 4.77 cm were sampled in 1997, 2002 and 2007. With the exception of the cerradão, there was a net reduction in tree density over the studied period of ten years, because mortality rates were higher than the recruitment rates. The basal area increased during the period of the study, especially at cerradão. The mean mortality rate in the studied area was 2.64%.yr-1 and 3.36%.yr-1 for the 1997-2002 and 2002-2007 periods, respectively, whereas the mean recruitment rate was 1.76%.yr-1 and 1.97%.yr-1, respectively. In general, mortality rates and recruitment rates have increased during the two successive periods of measurement and showed an imbalance in favor of mortality for the semideciduous seasonal forest and the gallery forest. This fact, added to the low density and high basal area, suggest that there was a process of thinning in the tree community. However, at cerradão, there was an imbalance in favor of recruitment, with a consequent increase in density and basal area, indicating that the cerradão is in a construction phase, which was further favored by a decrease in the occurrence of fire and other anthropogenic disturbances. When the turnover rates are taken into consideration, the global dynamics of the study area over the ten years evaluated can be expressed as cerradão > semideciduous seasonal forest > gallery forest. <![CDATA[<b>Demographic structure of a threatened palm (<i>Euterpe edulis</i> Mart.) in a fragmented landscape of Atlantic Forest in northeastern Brazil</b>]]> At the northern limits of the range of the palm species Euterpe edulis there is an endemic ecotype, known as the "Bahia" ecotype, which is distinguished by its reddish crownshaft and low seed production. Unfortunately, little is known about its demographic characteristics. Therefore, we contrasted the density of E. edulis populations in the Una region, in the southern part of the Bahia state, Brazil, with that of other populations of the species in southern and southeastern Brazil. In addition, within the Una region, we compared a long-protected forest fragment (F1) with three recently protected fragments (F2, F3, and F4), in terms of demographic parameters and plant size, in order to determine what influence, if any, time since protection has on E. edulis populations. Population densities within the Una region were higher than in regions where E. edulis populations are stressed by harvesting or intense seed predation but much lower than in regions with well protected populations. Among the Una fragments, density was highest in F1 and lowest in F2. The proportion of individuals at the various developmental stages differed among the fragments (χ²=25.219, df=12, p=0.014). Diameter at ground level, height, and number of leaves correlated positively among themselves and negatively with population density. For all developmental stages, F1 surpassed the other fragments in terms of densities and plant sizes. It is likely that the newly protected populations suffer the lingering effects of previous harvesting, which are reflected in their demography and in the size of their individual members. The viability of this low-density endemic ecotype must be established in order to assess the conservation status of the species on a regional scale. <![CDATA[<b>Density and fertility of <i>Byrsonima pachyphylla</i> A. Juss. (Malpighiaceae) in small fragments of the Brazilian <i>Cerrado</i></b>]]> Habitat fragmentation is one of the main threats to the biodiversity of the planet. This study was conducted in nine fragments of the Brazilian cerrado (savanna) sensu stricto. We assessed the effects that fragment size and distance between fragments has on the density and fertility of populations of Byrsonima pachyphylla A. Juss. (Malpighiaceae), known in Brazil as "murici". In each of the nine fragments, we evaluated seven individuals. We quantified the B. pachyphylla density within a 20-m radius around each individual. Fertility in each fragment was estimated by determining the ratio between the number of flowers and the number of fruits produced. We carried out linear regression analyses between mean B. pachyphylla density and fragment size, as well as between mean B. pachyphylla fertility and fragment size. The influence of spatial autocorrelation on the fertility of each studied plant was estimated by Moran's I to evaluate the effect of fragment distance on B. pachyphylla fertility. Population densities and the proportions of fertile plants were greater in the larger fragments, which were also more preserved. There was spatial autocorrelation only between plants in the same fragment. Neighboring fragments differed significantly in terms of fertility, which is probably related to the degree of preservation of each fragment. Habitat fragmentation has a marked effect on the fertility of plant species in the cerrado, and larger fragments are needed in order to maintain their populations and those of associated species. <![CDATA[<b>Clay content drives carbon stocks in soils under a plantation of <i>Eucalyptus saligna</i> Labill. in southern Brazil</b>]]> Soil carbon accumulation is largely dependent on net primary productivity. To our knowledge, there have been no studies investigating the dynamics of carbon accumulation in weathered subtropical soils, especially in managed eucalyptus plantations. We quantified the seasonal input of leaf litter, the leaf decomposition rate and soil carbon stocks in an commercial plantation of Eucalyptus saligna Labill. in southern Brazil. Our goal was to evaluate, through multiple linear regression, the influence that certain chemical characteristics of litter, as well as chemical and physical characteristics of soil, have on carbon accumulation in soil organic matter fractions. Variables related to the chemical composition of litter were not associated with the soil carbon stock in the particulate and mineral fractions. However, certain soil characteristics were significantly associated with the carbon stock in both fractions. The concentrations of nutrients associated with plant growth and productivity, such as phosphorus, sulfur, copper and zinc, were associated with variations in the labile carbon pool (particulate fraction). Clay content was strongly associated with the carbon stock in the mineral fraction. The carbon accumulation and stabilization in weathered subtropical Ultisol seems to be mainly associated with the intrinsic characteristics of the soil, particularly clay content, rather than with the quantity, chemical composition or decomposition rate of the litter. <![CDATA[<b>Phenology, caudex growth and age estimation of<i> Cyathea corcovadensis</i> (Raddi) Domin (Cyatheaceae) in a subtropical forest in southern Brazil</b>]]> Cyathea corcovadensis (Raddi) Domin occurs in northeastern, southeastern and southern Brazil, being widely distributed in the last. This was a three-year study, conducted from August 2008 to July 2011, in which we evaluated C. corcovadensis in a subtropical forest in southern Brazil. For the first year (August 2008 to July 2009), we monitored 30 plants on a monthly basis in order to analyze phenological events (vegetative and reproductive) and caudex growth. We also estimated the ages of the plants. Except in June and July of 2009, monthly leaf emergence and senescence were continuous and irregular, which prevented total leaf abscission, during that first year. Leaf emergence, senescence and fertility correlated with photoperiod, temperature and plant height, whereas rainfall was not a good predictor of C. corcovadensis phenophase. Within the forest fragment studied, the high proportion of fertile individuals (63.3%) indicated that the population has the potential to increase in size. The mean annual caudex growth rate was 4.66-8.23 cm and was statistically equivalent among the three years evaluated. The number of leaves per plant remained stable throughout the study period. Among plants that were 4 m tall, the mean estimated age was 60.3 years when calculated on the basis of overall height and mean annual growth rate, compared with only 46.9 years when calculated on the basis of the number of total leaf scars or petiole remains on the caudex and mean annual leaf production. <![CDATA[<b>Chemotaxonomy and flavonoid diversity of <i>Salvia L.</i>(Lamiaceae) in Iran</b>]]> In this study, we evaluated the chemotaxonomic status and chemical diversity of Salvia L. species in Iran using leaf flavonoid profiles. From natural habitats in the country, we collected samples of 14 species of the genus: S. spinosa L.; S. macrosiphon Boiss.; S. reuterana Boiss.; S. sharifii Rech.f. & Esfand.; S. nemorosa L.; S. virgata Jacq.; S. syriaca L.; S. mirzayanii Rech.f. & Esfand.; S. atropatana Bunge; S. limbata C. A. Mey; S. sclarea L.; S. ceratophylla L.; S. multicaulis Vahl.; and S. hydrangea Dc. ex Benth. Two-dimensional maps of these species were created with thin-layer chromatography. In order to study the taxonomic position of these species and 37 accessions, cluster analysis was applied. The results of the cluster analysis showed that S. spinosa was distinct from S. reuterana. Despite considerable morphological similarity between S. nemorosa and S. virgata, those two species are definitely distinguished. In addition, S. spinosa and S. macrosiphon were roughly grouped, whereas S. ceratophylla and S. multicaulis composed two separate groups. In the 14 species collected, the flavonoids identified were flavones, flavonols, flavanones, isoflavones, dihydroflavonols and chalcones. We found that flavonoids are appropriate indicators to determine the taxonomic position of Salvia species. <![CDATA[<b>Survival dynamics of <i>Melocactus conoideus</i> Buining & Brederoo (Cactaceae), a threatened species endemic to northeastern Brazil</b>]]> Studies on the survival of species are essential to understanding their biology and to developing effective conservation and management plans. This study aimed to determine the best model to explain the survival of the species Melocactus conoideus on the basis of time, density, age structure and habitat location, as well as to describe the interactions among those factors. The study was conducted in three M. conoideus habitat patches in the municipality of Vitória da Conquista, in the state of Bahia, Brazil, only one of which was within a "conservation unit" (protected area). In each patch, we selected 120 specimens of M. conoideus, which were marked with identification plates and classified by developmental stage and density. The survival of those individuals was monitored for a period of one year. The overall survival of M. conoideus was 87.5% and was found to correlate with the month, as well as with the interaction between the factors Patch and Density. Our results show that the survival of M. conoideus individuals is related to the intrinsic characteristics of each habitat patch and suggest that more areas should be set aside for the conservation of this species. <![CDATA[<b>Isolation and molecular characterization of <i>Rhizoctonia</i>-like fungi associated with orchid roots in the <i>Quadrilátero Ferrífero </i>and <i>Zona da Mata</i> regions of the state of Minas Gerais, Brazil</b>]]> Mycorrhizal associations can be considered required for orchids, which depend on the fungi for germination and establishment in natural conditions. Knowledge of the mycorrhizal fungi is important for programs aimed at the reintroduction, conservation and management of orchid species. The objective of this study was the molecular characterization of Rhizoctonia-like fungi from orchids in the Quadrilátero Ferrífero ("Iron Quadrangle") and Zona da Mata ("Forest Zone") regions of the state of Minas Gerais, Brazil. The affinities of these fungi were studied by comparing the rRNA internal transcribed spacer region with that of other isolates and sequences in GenBank. Three isolates had an affinity for Epulorhiza repens, and one was the holotypeof E. epiphytica.