Resumo em Inglês:

The objective of this study was to compare the ex situ and in situ floristic diversity of the soil weed seed bank of a rice field in northeastern Brazil. In a rice field in the county of Bacabal, located in the state of Maranhão, thirty 25-m² plots were laid out. From 15 plots, soil samples (6/plot; n = 90) were taken with a soil probe (25 × 16 × 3 cm) and placed in aluminum trays in the greenhouse. From the remaining 15 plots, weed samples (6/plot; n = 90) were taken with the same soil probe. The number of seeds was estimated by germination. We evaluated the numbers of species and individuals, as well as the density, frequency, abundance and importance value (IV) for each species. Diversity was computed by the Shannon index (H'). We recorded 13,892 individuals (among 20 families, 40 genera and 60 species), of which 11,530 (among 50 species) germinated ex situ and 2,362 (among 34 species) germinated in situ. The family Cyperaceae had the highest number of species (16), followed by Poaceae (10). The dominant species, in situ and ex situ, were Schoenoplectus juncoides (IV=47.4%) and Ludwigia octovalvis (IV=34.8%), respectively. Floristic diversity was higher ex situ (H'=2.66). The information obtained here could help determine the infestation potential of these species, which could lead to improved management strategies.

Resumo em Inglês:

A new species of Acanthothecis is described in the Atlantic Forest of northeastern Brazil. Unlike any other species in the genus, it has distinctly pseudo-stromatic ascomata that resemble those of the genus Sarcographa. However, its apically spinulose paraphyses, I-negative ascospores with thin endospore closely resemble those of other Acanthothecis species. A previous molecular phylogenetic analysis places the new species close to the type species of Acanthothecis, A. hololeucoides. The discovery of this unique new species underscores the importance of thorough biotic surveys in the Atlantic Forest of Brazil, where it is likely that many more unknown lichen species await discovery.

Resumo em Inglês:

We evaluated the phytotoxic effects that the hexane, ethyl acetate and methanol extracts from leaves and branches of the species Turnera ulmifolia L. and Turnera diffusa Willd. ex Schult. (Turneraceae), at concentrations of 1.25, 2.50, 3.75 and 5.00 mg ml-1, have on seed germination and seedling development in cucumber (Cucumis sativus L.). None of the extracts tested prevented germination, although the ethyl acetate extracts of T. diffusa, at 3.75 and 5.00 mg ml-1, reduced the mean germination speed and time to germination. Hexane extracts of both species reduced the main root length, number of secondary roots and hypocotyl length. In the ethyl acetate and methanol extracts, the number of secondary roots and hypocotyl length varied by species and concentration. Ethyl acetate extracts of T. ulmifolia at < 2.50 mg ml-1 stimulated growth of the main root and hypocotyl, as did T. ulmifolia methanol extracts at 1.25 and 3.75 mg ml-1; all other extract/concentration combinations had an inhibitory effect on those parameters. The hexane and ethyl acetate extracts of T. diffusa inhibited the formation of secondary roots and of the main root, although significant inhibition of hypocotyl growth was observed only at > 2.50 mg ml-1. Comparatively, T. diffusa extracts inhibited development to a greater degree, thus presenting greater allelopathic potential, than did T. ulmifolia extracts.

Resumo em Inglês:

Four neotropical species of Vigna Savi (Leguminosae, Phaseolinae) have potential value as forage crops or ornamentals and could be cultivated in tropical or subtropical areas, even on floodplains. In order to obtain useful data for their culture and taxonomy, the seed morphology, germination pattern (hypogeal or epigeal) and seedling development were studied. The studied species belong to different sections of the genus: V. adenantha (G.F.W. Meyer) Maréchal, Mascherpa & Stainier (Sect. Leptospron); V. candida (Vell.) Maréchal, Mascherpa & Stainier (Sect. Sigmoidotropis); V. caracalla (L.) Verdc. (Sect. Caracallae) and V. luteola (Jacq.) Benth. (Sect. Vigna). The seeds were collected during fieldwork conducted in northwestern and northeastern Argentina. The qualitative and quantitative characters of the seeds were registered, after which they were sown. The development of the emerged seedlings was followed, first in a greenhouse and thereafter in open field. We recorded the type of germination, the thigmotropic movements of the hypocotyl and of the stem, seedling architecture and plant longevity. These traits allowed us to differentiate the species and construct an identification key that could be useful for agronomic or floricultural purposes. The data obtained partially support the current taxonomic treatment of the genus.

Resumo em Inglês:

Differences in plant species richness and composition are associated with soil properties and disturbances such as fire, which can therefore be key determinants of species occurrence in savanna plant communities. We measured species richness, using nine plant functional traits and abundance to calculate three functional diversity indices. We then used model selection analyses to select the best model for predicting functional diversity and richness based on soil variables at sites with three different fire frequencies. We also calculated the community-weighted mean of each trait and used ordination to examine how traits changed across fire frequencies. We found higher species richness and functional dispersion at sites that were more fertile and where fire was frequent, and the opposite at such sites where fire was infrequent. However, soil properties influenced functional evenness and divergence only where fire was infrequent, with higher values where soils were poorer. Fire can change functional traits directly by hindering development of plants and indirectly by altering competition. Different fire frequencies lead to different plant-soil relationships, which can affect the functioning of tropical savanna communities. Functional diversity components and functional identity of the communities are both affected by fire frequency and soil conditions.

Resumo em Inglês:

The sterile corticolous crustose lichen Protoparmelia capitata (Ascomycota: Parmeliaceae), recently described for southeastern North America, is reported as a new record for South America in the Serra da Jiboia mountain range, near the municipality of Santa Teresinha, in the state of Bahia, in northeastern Brazil. This species is locally common and is probably closely related to P. isidiata, which has the same pigmentation and medullary chemistry, P. capitata differing from P. isidiata in that the former features soredia rather than isidia.

Resumo em Inglês:

Prior to sowing, seeds of Brassica juncea Czern and Coss cv. Varuna were soaked in water (controls) or in 50, 100 or 150 mM of sodium chloride (NaCl) for 6 h. The resulting plants, at 15, 30 and 45 days after sowing (DAS) were either not treated (controls) or were treated with aqueous solutions of the hormone 28-homobrassinolide (HBL), which was applied to their foliage in concentrations of 10-10, 10-8 or 10-6 M. The concentration of NaCl showed an inverse correlation with the activity of nitrate reductase (EC 1.6.6.1), the activity of carbonic anhydrase (EC 4.2.1.1), chlorophyll content at 60 DAS, the rate of photosynthesis at 60 DAS, and seed yield at 140 DAS (at harvest), all of which decreased in parallel with increases in NaCl concentration. However, treatment with HBL attenuated those decreases and neutralized the ill effects of salinity stress, completely at the lowest NaCl concentration and partially at the higher NaCl concentrations. The seed yield of the crop can be increased by the foliar application of HBL, even under conditions of salinity stress.

Resumo em Inglês:

Bryophytes constitute an important component of tropical rain forests, which provide microhabitats favorable for their establishment. Bryophytes are also quite responsive to changes in microclimate, which makes them good bioindicators. This study aimed to determine the diversity and distribution of bryophytes in upper and lower montane forests of the Chapada Diamantina region of the state of Bahia, Brazil. To that end, we studied community aspects such as richness, diversity, substrates colonized, life forms and floristic similarity between areas and regions. In 2007 and 2008, we collected specimens from six forest sites, located from the north to the south of the Chapada Diamantina region. We identified a total of 205 infrageneric taxa. In comparison with the lower montane forests, the upper montane forests presented higher diversity and species richness, as well as greater numbers of substrates colonized, life form types, species of restricted geographic distribution and species typical of shaded areas. We also found low similarity in the species composition, the populations of the upper and lower montane forests forming two large and distinct groups. Although presenting relatively high floristic homogeneity among themselves, the Chapada Diamantina areas presented little similarity with those of the Atlantic Forest. This can be explained by the differences between the two regions in terms of environmental conditions, precipitation, seasonality, elevation and continentality.

Resumo em Inglês:

We analyzed the effects that passage through the guts of seven didelphid species had on the seed germination of 10 plant species. This study was conducted in an area of riparian woodland in a cerrado (savanna) reserve in southeastern Brazil. We found seeds of 23 angiosperm species in 427 fecal samples obtained from seven didelphid species. The plant families most often represented by the seeds found in the fecal samples were Melastomataceae (5 species) and Rubiaceae (4 species) . Most gut-passed seeds showed no significant difference in germinability when compared with the hand-extracted seeds. Among the ingested seeds, only those of Clidemia urceolata DC. (Melastomataceae) and Myrcia sp. (Myrtaceae) showed an increase in germinability (final proportion of germinated seeds), indicating that didelphid gut passage does not always benefit seed germination. The average germination time of consumed seeds ranged from 12 days (Cipocereus minensis (Werderm.) Ritter) to 171 days (Cordiera sessilis (Vell.) Kuntze). The small number of seeds destroyed after gut passage and the results obtained during the germination experiments underscore the importance of didelphid marsupials to the dynamics of plant reproduction, especially those of small-seeded cerrado species.

Resumo em Inglês:

The objective of this study was to evaluate the taxonomic composition and richness of the genera Trachelomonas and Strombomonas (pigmented Euglenophyceae) in a subtropical urban lake (30º03'05"S; 51º10'34"W) within the Botanical Garden, in the city of Porto Alegre, located in the state of Rio Grande do Sul, Brazil, in order to contribute to the floristic knowledge of Euglenophyta in artificial urban lakes. From July 2007 to June 2008, we collected samples monthly from two sampling stations, using a 25-µm mesh plankton net. The samples were preserved in 4% formaldehyde. We evaluated the following environmental variables related to the water in the lake: ammonia content, silica content, organic matter content, dissolved oxygen concentration, temperature, pH, depth, transparency, electrical conductivity and rainfall. To study the species composition in relation to environmental factors, we used cluster analysis, principal components analysis, canonical correspondence analysis and indicator species analysis. At the specific and infraspecific level, 22 taxa were identified, Trachelomonas elliptica (Playf.) Defl. and T. gracillima Bal. & Dast. representing new records for the state of Rio Grande do Sul. The cluster analysis indicated seasonal variation, species richness being highest in the spring of 2007. Seven indicator species were characterized as acid-tolerant.

Resumo em Inglês:

Most studies of the interactions between plants and gall-inducing (galling) insects have focused on the entomological aspects, few having addressed the diversity of galls in relation to the characteristics of the host plants. The objective of this study was to analyze the richness and composition of the community of host plants of galls in areas of cerrado (savanna) in the state of Goiás, Brazil. To that end, we inventoried the galls in different regions of the state and within various types of vegetation formations, between 2005 and 2007. We registered 80 gall morphotypes in 58 species of host plants (30 families and 47 genera). The host family with highest diversity of galls was Fabaceae, with 17 morphotypes, followed by Styracaceae, with seven. In the cerrado, Fabaceae is the plant family with the highest number of species. Our results show that the composition of a plant community is a determinant of the distribution of galling insects. At the family or genus level, the presence of certain taxa increases the species richness of the population of galling insects.

Resumo em Inglês:

This study investigated pollination mechanisms and breeding systems in five Commelina variants: two subspecies of Commelina diffusa (C. diffusa subsp. aquatica and C. diffusa subsp. montana, each having two staminodes); two variants of C. erecta (with three staminodes); and C. lagosensis (also with three staminodes). In all three species, the staminodes have six lobes but only two fertile lateral lobes. We collected field samples and cultivated new plants from stem cuttings. When the plants flowered, we evaluated floral morphology, floral biology and breeding systems, creating eight separate experimental treatments, involving spontaneous and hand pollination, as well as varying degrees of emasculation of the flowers. Although the pollen from the lateral and central anthers was capable of siring seeds, the staminode pollen rarely set seeds. Commelina diffusa subsp. aquatica presented very low percent pollen stainability in all three of its stamens and produced no seeds in any of the pollination treatments. In all three species, the stigma was often directed toward the central anther during coiling of the style. Our results show that C. diffusa subsp. aquatica is sterile and that, in the other Commelina variants studied, pollination occurs mainly through autogamy via the lateral and central anthers.

Resumo em Inglês:

Much remains to be learned about biological diversity, which constitutes a valuable natural resource. Due to the pressure that human activity has put on natural resources, biodiversity has been reduced, often unbeknownst to those responsible for that activity. Therefore, we aimed to perform a quantitative and qualitative analysis of periphytic algae in the Itupararanga reservoir, correlating the results with the physical and chemical characteristics of the water, as well as with climatic conditions. To that end, five samples were collected at four sampling stations in the Itupararanga reservoir during the year 2010. Aquatic macrophytes were collected with a 156-cm² frame, and the periphytic algae were scraped free of the macrophytes with a brush. Samples were fixed in formaldehyde and Lugol's solution for the qualitative and quantitative analyses, respectively. We identified 156 taxa belonging to eight classes, and the overall density was 10,200-171,800 individuals/mm². The taxonomic composition and abundance of periphyton were found to be dependent on spatial and temporal factors, such as the type of substrate and the characteristics of the sampling site, as well as seasonal variations in the chemical and physical properties of the water.

Resumo em Inglês:

The consumption of dietary supplements and herbal mixtures to promote weight loss is a common practice in the West. This study was undertaken in Mexico City, surveying stores selling "natural products" at subway stations. The aims of this paper were as follows: to compile a record of plant products marketed as slimming aids and of retailer perceptions of these products; to review the pharmacological and ethnobotanical literature on the species declared; and to create an optical micrograph of a subset of products to verify the accuracy of the list of component plant species shown on the labels. We applied the techniques of observation, semi-structured interviews and free-listing at the retail stores. Results are presented for the 75 species recorded in the 41 weight-loss products surveyed, showing which plant parts are used, the geographical distribution of the species, pharmacological effects, dosage, route of administration and method of preparation, as well as ethnobotanical information derived from fieldwork. We discuss the values assigned to the species used. Microscopic analyses revealed that many of the plant ingredients declared were absent, highlighting the need for greater quality control and safety of these herbal remedies.

Resumo em Inglês:

The fruits of the palm Butia capitata are harvested from wild populations. A lack of knowledge of their ecology has hindered the establishment of sustainable management practices. We investigated fruit biometric parameters, yield and phenology in two populations of B. capitata in the cerrado (savanna) in the north of the state of Minas Gerais, Brazil, at two study sites: in the communities of Mirabela (Fazenda Baixa site, studied from December 2006 through December 2007) and Campos (studied throughout 2007). Overall, adult palms produced an annual average of 7.6 leaves. At the Fazenda Baixa site, the mean annual number of infructescences was 4.9, compared with only 1.6 at the Campos site, and the annual yield was 197-373 and 145-468 fruits per tree (in 2006 and 2007, respectively), compared with 67-247 at the Campos site. Reproductive events were seasonal and influenced by rainfall distribution. Typically, inflorescences and immature infructescences appeared in the dry season, mature infructescences appearing in the rainy season. Inflorescence production and fruit biometric parameters differed between the two populations. Fruit yield correlated with height and leaf biomass. We found that B. capitata fruits, which are highly perishable, should be harvested when nearly-ripe and remain attached to the infructescence during transport. Our findings have important implications for the development of strategies for sustainable management and in situ conservation of populations of this species.

Resumo em Inglês:

In nature, orchid seeds obtain the nutrients necessary for germination by degrading intracellular fungal structures formed after colonization of the embryo by mycorrhizal fungi. Protocols for asymbiotic germination of orchid seeds typically use media with high concentrations of soluble carbohydrate and minerals. However, when reintroduced into the field, seedlings obtained via asymbiotic germination have lower survival rates than do seedlings obtained via symbiotic germination. Tree fern fiber, the ideal substrate for orchid seedling acclimatization, is increasingly scarce. Here, we evaluated seed germination and protocorm development of Cyrtopodium glutiniferum Raddi cultivated in asymbiotic media (Knudson C and Murashige & Skoog) and in oatmeal agar (OA) medium inoculated with the mycorrhizal fungus Epulorhiza sp., using non-inoculated OA medium as a control. We also evaluated the performance of tree fern fiber, pine bark, eucalyptus bark, corncob and sawdust as substrates for the acclimatization of symbiotically propagated plants. We determined germination percentages, protocorm development and growth indices at 35 and 70 days of cultivation. Relative growth rates and the effects of substrates on mycorrhizal formation were calculated after 165 days of cultivation. Germination efficiency and growth indices were best when inoculated OA medium was used. Corncob and pine bark showed the highest percentages of colonized system roots. The OA medium inoculated with Epulorhiza sp. shows potential for C. glutiniferum seedling production. Corncob and pine bark are promising substitutes for tree fern fiber as substrates for the acclimatization of orchid seedlings.

Resumo em Inglês:

The family Thelypteridaceae presents considerable species richness throughout the hillside forests and coastal plains of Brazil, as well as in the forests of its southern plateau. This study was based on material collected in 24 trips to various regions within the state of Mato Grosso, as well as material deposited in the principal Brazilian herbaria and in other herbaria. The genus Thelypteris, represented in this study by the subgenera Amauropelta (Kunze) A.R. Sm., Cyclosorus (Link) Morton and Steiropteris (C. Chr.) K. Iwats., comprises 11 species in Mato Grosso and surrounding regions. Keys for identification, descriptions and references to illustrations of diagnostic characters are presented.

Resumo em Inglês:

Protected areas are important sources providing plant resources for human populations, and contributing to the livelihood and income of families. To test the ecological apparency hypothesis, that there is positive relationship between the visibility of a species and its use, we conducted an ethnobotanical survey in the protected area of the Itaúna rural settlement in the municipality of Planaltina, in the state of Goiás, in central Brazil. The phytosociological parameters were obtained in 5.6 ha area of the Brazilian cerrado (savanna), and the ethnobotanical survey conducted with semi-structured interviews with 75 people. There was a weak positive correlation between the use value and the phytosociological parameters. A principal component analysis showed that seven species (Pterodon pubescens, Hancornia speciosa, Hymenaea stigonocarpa, Eugenia dysenterica, Annona crassiflora, Stryphnodendron adstringens and Solanum lycocarpum) have high use value, despite having low density, dominance and frequency. Nineteen species showed a positive relationship between their use value and their phytosociological parameters. The relationship between vegetation structure and use value differed among species in the protected area, indicating that more attention should be paid to those under more pressure, with low abundance. Further studies of these seven species should be conducted to determine whether human pressure is affecting populations structures and to define management strategies.

Resumo em Inglês:

The vegetation of the Brazilian restinga (coastal woodland) presents a variety of species and different characteristics, encompassing fields, fruit groves and forests on quartzarenic neosols. We hypothesised that the structure of the restinga landscape along the coast of the state of Piauí is influenced by edaphic factors and presents a pattern similar to that of other northeastern restingas. We evaluated three restingas in Piauí, using the quarter method to determine their structure. Composite soil samples were collected to determine their chemical and physical properties. Edaphic variables were correlated with plant species by canonical correspondence analysis (CCA). Phytosociological data for all three areas indicated regenerating vegetation comprising several small individuals, 82.5% of which showed a diameter at ground level < 13 cm. We also observed considerable tillering. In two of the areas, there was a predominance of Fabaceae species, such as Caesalpinia pyramidalis and Copaifera martii. Although the structural characteristics of the restingas studied were similar to those of other northeastern restingas, the former showed lower Shannon diversity indices (2.18-2.44). The CCA indicated that species distribution was influenced by edaphic factors such as pH, aluminium content and amount of organic matter. The restingas studied were similar to others along the Brazilian coast.

Resumo em Inglês:

The chemical compounds of Cladia aggregata from the states of Paraná and Santa Catarina were analyzed, resulting in five chemotypes. The chemotypes are as follows: barbatic and 4-O-demethylbarbatic acid; barbatic, 4-O-demethylbarbatic, and homosekikaic acid; barbatic, 4-O-demethylbarbatic and diffractaic, or barbatic and diffractaic acid; barbatic, 4-O-demethylbarbatic, and fumarprotocetraric acid; and barbatic, 4-O-demethylbarbatic, and stictic acid.

Resumo em Inglês:

The aim of this study was to complete the species list and disseminate data regarding the diversity of bryophytes in the state of Rio Grande do Sul, Brazil. We registered 51 species of bryophytes (11 mosses and 40 liverworts) as new records for Rio Grande do Sul, of which six represent the second records for Brazil.