Resumo em Inglês:

In this article, we review allelopathy studies conducted in Brazil or involving plant species that occur in the country. Conceptions and misconceptions associated with allelopathy, as well as some international criteria to be applied in allelopathic research, are presented and discussed. We observed a sharp increase in the number of papers on this subject conducted in Brazil between 1991 and 2010. However, most studies are conducted under laboratory conditions, lack a clear hypothesis or a solid justification, and typically make use of target species that do not co-exist with the donor species under natural conditions. We also found that most studies do not take the additional steps in order to purify and identify the bioactive molecules. We recommend that further studies be conducted in order to explore the potential of plant biodiversity in Brazil. Such studies could lead to the development of new molecular structures (allelochemicals) that could be used in the control of pests and weeds, thereby reducing the use of the harmful synthetic herbicides that are currently being widely employed.

Resumo em Inglês:

Swamp forests are associated with soils that are saturated or inundated because of a high water table. In Brazil, little is known about the plant ecology of such forests. In this paper, we aimed to describe the phytosociological structure of the tree layer of swamp forests in Restinga de Jurubatiba National Park, in the northern part of the state of Rio de Janeiro, and to evaluate the floristic similarities between these forests and some other possibly related types of vegetation formations in Brazil. The sampling included 84 species, within 62 genera and 34 families. The Shannon diversity index was 3.42, and the Shannon evenness index was 0.77. The forests studied showed an oligarchic structure; Tapirira guianensis, Calophyllum brasiliense and Protium icicariba were the most important species. Oligarchy, or monodominance, and relatively low species richness are the norm in the swamp forests of southeastern Brazil and result from the strong selective character of the saturated/inundated soils. In comparison with local areas of restinga (coastal woodland), Atlantic Forest sensu stricto, other swamp forests and flooded riparian forests, the similarity was low (Jaccard similarity coefficient < 0.25). In addition to the similar ecological conditions, geographic proximity was a key factor determining the patterns of similarity found. Our results indicate that the swamp forests of southeastern Brazil do not represent a distinguishable floristic unit, due to sources of local variation, notably migration and the establishment of adaptive species from neighboring vegetation formations (some 70% of the species surveyed).

Resumo em Inglês:

The order Asparagales comprises 14 families, five of which occur in Brazil. Amaryllidaceae is a family of economic relevance and includes numerous ornamental genera. The genus Hippeastrum is widely distributed in Brazil and comprises 34 species, 11 of which occur in areas of restinga (coastal woodland) and Atlantic Forest in the state of Rio de Janeiro. The morphology of Hippeastrum has not been extensively studied in Brazil, where only a few systematic floristic surveys have been carried out with native species. In field studies and reviews of herbarium collections, we identified five Hippeastrum species occurring in areas of restinga in the state of Rio de Janeiro. The five species identified could be distinguished according to the following palynological characteristics: pollen grain size, polarity, pollen units, shape, aperture (number and type), exine sculpture, colpus length and pattern of sexine ornamentation. Of the five species identified, Hippeastrum aulicum Herb. and H. glaucescens (Ker Gawl.) Herb. were not identified in the field. Among the three species that were found in the field, H. striatum had the widest distribution in the study area, whereas the distribution of H. reticulatum was restricted to a single area of restinga, in the Jaconé district of the municipality of Saquarema. Through palynological examinations of specimens from herbaria in the state of Rio de Janeiro, we were able to confirm the identity of all five species of Hippeastrum studied. Our data represent a relevant contribution to increasing knowledge of this plant group in the region and will aid in future conservation efforts.

Resumo em Inglês:

The genus Centaurea L. is one of the largest genera in the family Asteraceae. The number of taxa included in this genus ranges from 500 to 600 worldwide. Iran is one of the major centers of diversity for this genus. Pollen morphology has proved useful in the systematics of Asteraceae, as well as in that of some of its genera and species. The pollen morphology of 19 taxa of the genus Centaurea was investigated in detail by light and scanning electron microscopy. Examination under light microscopy showed pollen grains to be tricolporate, isopolar, radially symmetrical, oblate spheroidal, prolate spheroidal, subprolate, tectum perforate and scabrate. Based on the exine ornamentation observed under scanning electron microscopy, we identified two types of pollen grains, designated type I (dense acute spinules) and type II (sparse spinules). All of the taxa evaluated resemble Wagenitz's Jacea type. We present micrographs of pollen grains, together with descriptions of the characteristics of their structure. We found that the pollen characters (shape, exine structure, sculpturing) were useful for classification.

Resumo em Inglês:

The plant population dynamic is affected by ecological and evolutionary processes that operate at all stages of the plant life cycle. The aim of this study was to characterize the seed and seedling performance of Copaifera langsdorffii by testing four hypotheses: the resource concentration hypothesis; the relationship between seed size and germinability hypothesis; the relationship between seed size and seedling vigor hypothesis; and the intraspecific seedling competition hypothesis. All seeds used in the experiments were collected from 35 C. langsdorffii plants located in a fragment of the Brazilian cerrado (savanna). The number of fruits per plant negatively affected Rhinochenus brevicollis attacks on C. langsdorffii seeds. Therefore, this result does not support the resource concentration hypothesis, and predator satiation was used in order to explain the observed result. In general, seed germinability (percentage and time to emergence) was not influenced by seed size. The homogeneity of the experimental design, together with an abundant water supply, may have masked the effects of seed size on germinability. Seed size positively affected seedling development, corroborating the expected relationship between seed size and seedling vigor. The number of seedling per plastic bags negatively affected the growth of C. langsdorffii. The nutrient-limited soil probably promoted the below-ground competition for nutrients among seedlings. Finally, the role of evolutionary and ecological factors on C. langsdorffii population dynamics is discussed.

Resumo em Inglês:

The main goal of this study was to determine the diversity and activity of arbuscular mycorrhizal fungi (AMF) in an area degraded by limestone mining within the semi-arid region of Brazil known as the caatinga (shrublands). Near a limestone quarry, we selected two areas of caatinga (preserved and degraded) for study. The number of glomerospores did not differ significantly between the two areas. There was a trend toward the most probable number of infective propagules being higher in the degraded area. Twenty AMF taxa were identified in the two sampled areas, species richness, diversity and evenness being higher in the preserved area. Two species of Racocetra represent new records for the semi-arid region of Brazil. Glomerospore production and AMF species richness were unaffected by mining activity in the study area.

Resumo em Inglês:

We report a new diatom species for the Atlantic Forest of Brazil. The species, designated Eunotia trigona Fuhrmann, Metzeltin & Tremarin sp. nov., is also new to science. It was found on moss in the Itatiaia mountain range in the state of São Paulo. Among the Eunotia taxa, E. trigona is distinguished by its unusual (perhaps unique) triangular-shaped valve, similar to those found in a few species of the genera Staurosira and Staurosirella.

Resumo em Inglês:

Here, we describe the development of sporangial and gametangial conceptacles for Amphiroa beauvoisii and A. vanbosseae; sporangial conceptacles only for A. misakiensis; and gametangial conceptacles only for A. cryptarthrodia and A. rigida. The descriptions are based on the observation of histological preparations obtained from 112 specimens collected from the Gulf of California, in Mexico, and the Azores archipelago of Portugal. Information on the development of the sporangial conceptacle pore and conceptacle senescence is here described and illustrated for the first time. Four development patterns were observed: two for sporangial conceptacles; one for spermatangial conceptacles; and one for carposporangial conceptacles. The phases of development of the sporangial conceptacle were found to be useful in delimiting species within the genus. Based on the sporangium location on the cavity floor and the pore canal anatomy, the species A. beauvoisii, A. misakiensis and A. vanbosseae can be distinguished from each other.

Resumo em Inglês:

We applied an "adapted" protocol for collecting and processing pollen grains in the pollen analysis of the post-emergence residue of Melipona (Melikerria) interrupta Latreille. The study was conducted at the Sant'Ana honey farm, located on the banks of the Solimões River, in the municipality of Manacapuru, in the state of Amazonas, Brazil, where a colony was monitored in October and November 2010. From that colony, 10 samples of post-emergence residue were collected. Unlike in the acetolysis method, there was no need to expose pollen grains to an acidic medium, because pollen loses its content during the larval digestive process. We identified 32 pollen types, from 19 botanical families, plus three undetermined pollen types. The most representative family was Fabaceae (Mimosoideae), with eight pollen types, Mimosa guilandinae being the most common species. Only the pollen of Miconia (Melastomataceae), with 74.10%, was classified as a common pollen. We also found that the pollen of Mimosa pudica (Fabaceae: Mimosoideae) retained its content, indicating that not all resources furnished by workers are utilized by the larvae. The protocol applied here, despite omitting the acetolysis process, was efficient, providing full details of pollen contained in post-emergence residue.

Resumo em Inglês:

Polyploidization is common among angiosperms and might induce typically allogamous plants to become autogamous (self-compatible, relying on sexual self-fertilization) or apomictic (achieving asexual reproduction through seeds). This work aimed to determine whether neopolyploidy leads to the breakdown of the self-incompatibility system in the hexaploid non-apomictic species Handroanthus serratifolius (Vahl) S. Grose, through analyses of its floral biology, pollination biology and breeding system. Although anthesis lasted for three days, increasing the overall floral display, receptivity decreased as of the second day. Centridini and Euglossini bees were the main pollinators, and low nectar availability (1.95 ± 1.91 µl/flower) might have obliged them to visit multiple flowers. We observed low reproductive efficacy. That might be explained by self-sterility and by the great number of flowers per individual, which could increase the frequency of geitonogamy. Ovule penetration by the pollen tubes in self-pollinated pistils with posterior abscission indicated late-acting self-incompatibility in H. serratifolius, as observed in other diploid Bignoniaceae species, although inbreeding depression cannot be excluded. The self-sterility found in the monoembryonic, hexaploid individuals studied here contrasts with the results for other neopolyploid Handroanthus and Anemopaegma species, which are often autogamous and apomictic. Our results suggest that neopolyploidy is not the main factor leading to self-fertility in Handroanthus.

Resumo em Inglês:

It is known that the efficient dispersal is one among other features that amplify the invasion potential of a plant. Knowledge of the ontogeny, morphology and fruit dispersal of species is indispensable for weed control in crops. To identify the pericarp structures involved in the fragmentation and dehiscence processes and other features related to dispersal, we studied the pericarp development of Aeschynomene evenia Wright, Desmodium incanum (Sw.) DC. and Vigna luteola (Jacq.) Benth. (Fabaceae-Faboideae), all of which are considered weeds in certain situations. For light and scanning electron microscopy studies, we fixed and processed buds, flowers and fruits, according to usual methods, at different stages of development. We observed that the sclerenchymatous endocarp is essential for dehiscence in legumes, as well as for fragmentation in loments. We also found that the presence of hook-shaped trichomes, sclereid nests in the mesocarp, septum, hypodermis and the formation of false septa are essential to the diaspore dispersal of the species studied.

Resumo em Inglês:

We evaluated the ontogeny of the understory shrub Psychotria tenuinervis Müll.Arg., considering morphological and morphometric characters. Four ontogenetic stages were identified: seedling, juvenile, immature and adult (vegetative and reproductive phases). Size measurements and allometric relationships of the stem and crown were compared between the immature and adult stages. Diameter and total height of the stem, as well as crown depth and width, increased throughout the ontogenetic stages and differed among immature, vegetative adult and reproductive adult individuals. The number of branches was lower in immature individuals than in vegetative and reproductive adult individuals but did not differ between the last two. The bifurcation ratio did not vary during ontogenetic development. In general, allometric relationships between the stem and the crown were similar among the ontogenetic stages. Although there was a progressive increase in size during ontogenetic development, there was no change in the allometric relationships between the size variables and architecture of P. tenuinervis, indicating that the form of individuals does not change over the course of ontogeny.

Resumo em Inglês:

Sporophyte morphology has been traditionally used in taxonomic studies of pleurocarpous mosses. However, the gametophyte morphology of the Pilotrichaceae still holds interesting and under-investigated characters. Here, we conducted an in-depth investigation of the morphology and development of Pilotrichaceae leaf papillae and assessed their usefulness in inferring the evolutionary history of the family. Specimens were observed under scanning electron microscopy, and we identified seven morphological types of papillae, as well as two different pathways of development. Our results suggest that papilla morphology and development are phylogenetically informative in the Pilotrichaceae.

Resumo em Inglês:

This study presents the first taxonomic inventory of the order Zygnematales in the Litoral Norte Environmentally Protected Area, in the state of Bahia, Brazil. Fifty samples of planktonic and periphytic material were collected, from lotic and lentic environments, during the summer (January-March) and winter (June-August) of 2009. We identified 18 taxa distributed among five genera (Cylindrocystis, Mougeotia, Netrium, Spirogyra, and Spirotaenia). Of those 18 taxa, eight were new additions to the Brazilian desmid flora: Mougeotia calcarea; Mougeotia elegantula; Spirogyra gracilis; Cylindrocystis crassa var. elliptica; Cylindrocystis brebissonii var. minor; Cylindrocystis brebissonii var. turgida; Netrium digitus var. parvum; and Netrium oblongum var. oblongum. The geographical distributions of ten taxa were extended to include northeastern Brazil.

Resumo em Inglês:

This study aimed to analyze relationships among the structure of the tree component, edaphic variables and canopy discontinuity along a toposequence in a seasonal upland (hillside) forest in southern Brazil. Soil and vegetation were sampled in 25 plots of 20 × 20 m each. We described the vegetation in terms of structure, richness and diversity, as well as by species distribution patterns. We evaluated canopy continuity, determined sloping and calculated spatial coordinates. We applied partial canonical correspondence analysis (pCCA) to determine whether species distribution correlated with environmental and spatial variables. We identified 1201 individuals belonging to 76 species within 30 families. The species with highest density and frequency were Gymnanthes concolor Spreng., Calyptranthes tricona D.Legrand, Eugenia moraviana O.Berg and Trichilia claussenii DC. The pCCAs indicated significant correlations with environmental and spatial variables. Sand content, boron content and soil density collectively explained 36.17% of the species matrix variation (total inertia), whereas the spatial variables x, y and xy² collectively explained 14.27%. The interaction between environmental and spatial variables explained nearly 4.5%. However, 45.05% remained unexplained, attributed to stochastic variation or unmeasured variables. Terrain morphology and canopy discontinuity had no apparent influence on richness, and changes in species distribution were correlated with sloping, which affects soil features and determines the directional distribution of some species.

Resumo em Inglês:

Here, we describe pollen grains extracted from a Pleistocene-Holocene sediment core (BU-91-GL-05; 22°48'45"S; 41°54'13"W) taken from the Albacora Slope (22°48'45"S; 41°54'13"W), located in the Campos Basin of the northern region of the state of Rio de Janeiro, Brazil. The analysis resulted in the identification and morphological description of 46 types of pollen: one of a gymnosperm genus (Podocarpus); and 45 of angiosperm taxa across 27 families-one family of monocotyledons (Poaceae) and 26 families (30 types) of dicotyledons. The most common angiosperm families were Amaranthaceae (Chenopodium, Amaranthus and Gomphrena); Fabaceae (Fabaceae type, Bauhinia, Inga and Canavalia); Malpighiaceae (Tetrapteris, Heteropteris and Peixotoa); Malvaceae (Sida, Abutilon, Hibiscus and Pseudobombax); Rubiaceae (Faramea, Borreria and Psychotria); Asteraceae (Eupatorium and tribe Vernonieae); Bignoniaceae (Bignoniaceae type, Adenocalymma and Tabebuia); and Onagraceae (Fuchsia and Ludwigia). The palynoflora in this study are associated with dense montane and submontane Atlantic Forest, semideciduous forest and restinga (coastal woodland), all of which are present in the state of Rio de Janeiro. Palynological analysis can provide important data about paleovegetation and paleoclimatic changes in the studied area during the Quaternary, specifically in the last 145,000 years.

Resumo em Inglês:

In this study, we evaluated the growth of the liverwort Lunularia cruciata, inoculated or not with the arbuscular mycorrhizal fungi (AMF) Glomus proliferum (15 spores per Petri dish), in Strullu-Romand Variant (SRV) medium modified and enriched with humic acid (HA) at different concentrations (0, 20, 40 and 80 mg C L−1), as well as the sporulation of the AMF. We assessed the absolute growth rate (AGR) and relative growth rate (RGR) at inoculation, as well as at 7, 14, 21, 28, 43, 52 and 60 days after inoculation (DAI), whereas we assessed sporulation at 25, 43, 60 and 70 DAI. The main determinant of L. cruciata growth was the presence of AMF. With and without G. proliferum inoculation, respectively, the AGR peaked at 39 and 42 DAI, and the RGR was 0.0474 and 0.0387 cm² cm−2 d−1. Doses of 20 and 80 mg C L−1 of HA had a positive influence on the growth of L. cruciata. With and without HA, respectively, the AGR peaked at 38 and 39 DAI, and the RGR was 0.0484 and 0.0422 cm² cm−2 d−1. The sporulation of G. proliferum, which was as high as 199 spores plate−1, was influenced by HA, especially at 20 and 80 mg C L−1.

Resumo em Inglês:

The characterization and viability of pollen grains are useful tools to guide crosses in breeding programs. The objective of this study was to describe the morphological patterns and viability of pollen grains from five accessions of Passiflora edulis f. flavicarpa O. Deg. and five accessions of Passiflora setacea DC. Pollen morphology descriptions were made using light microscopy and scanning electron microscopy, whereas the viability analysis was performed by in vitro germination and histochemical analysis (Lugol's solution and 2,3,5-triphenyltetrazolium chloride). Pollen grains assessed for germination were inoculated in culture medium containing Ca(NO3).4H2O (0.03%), Mg(SO4).7H2O (0.02%), KNO3 (0.01%), H3BO3 (0.01%), sucrose (15%) and agar (0.8%). Although P. edulis and P. setacea showed the same shape and type of pollen aperture, the two differed in terms of their morphology and exine ornamentation pattern. In vitro analysis showed that one of the P. edulis f. flavicarpa accessions (designated BGP 330) presented the highest germination rate (53.98%) and longest pollen tube (2.18 mm). The histochemical analysis overestimated pollen viability when compared with the in vitro results. The results of this study contribute to the breeding of Passiflora species by increasing the understanding of their morphology and pollen grain viability.

Resumo em Inglês:

We conducted a floristic survey of ferns within the Murici Ecological Station (remnant of the northeastern Atlantic Forest), located near the municipalities of Messias and Murici, in the state of Alagoas, Brazil. To increase knowledge of the ferns of Alagoas, we evaluated the species occurring in the study area in terms of richness, composition, geographic distribution, similarities with species in other Brazilian biomes, regional conservation status and ecological aspects. Data were obtained from field work conducted between March 2009 and September 2010. We identified 107 species of ferns, of which 19 represent new records for Alagoas. The richest families were Pteridaceae (29 species) and Polypodiaceae (22 species). The richest genera were Adiantum (15 species) and Thelypteris (9 species). Most of the species sampled are widely distributed throughout Brazil and the Americas. Within the context of the northeastern Atlantic Forest, 12 species were considered endangered. Concerning the ecological aspects, 88.8% of the species identified were herbaceous, 57.9% were terrestrial and 70.0% occurred in the forest interior.

Resumo em Inglês:

This study aimed to relate changes in structure and species diversity with edaphic variables (soil type and flooding regime) in a gradient of forest formations within the Brazilian restingas (coastal woodlands). The study was carried out in the Jacarenema Municipal Natural Park, in the city of Vila Velha, in the Espírito Santo State, Brazil. We evaluated the structure of shrub and tree components by sampling 80 plots of 5 × 25 m each, equally distributed among four forest types (well-drained, transitional, floodplain and flooded). We included all individuals with a ≥ 3.2 cm diameter at breast height. From each plot, soil samples (for chemical and physical analysis) were collected at a depth of 0-10 cm. We identified a significant fertility gradient (of soil nutrient availability) and a strong influence of groundwater on each forest type. We also found significant differences among the forest types in terms of individual basal area and height, as well as density. Diversity increased along the environmental gradient, from flooded to well-drained forest. We conclude that variations in structure and diversity among the four forest types were correlated with the flooding regime, as well as with chemical and physical characteristics of the soil.

Resumo em Inglês:

Parmotrema hydrium is a new lichen species discovered during a survey of Parmeliaceae in the Cantareira mountain range of southeastern Brazil. In its medullary chemistry, the species contains several fatty acids and other substances, including small amounts of atranorin, typically restricted to the soralia and young lobes.

Resumo em Inglês:

We investigated the distribution of epiphytic macroalgae on the thalli of their hosts at eight localities along the southeastern coast of Cuba between June 2010 and March 2011. We divided he epiphytes in two groups according to their distribution on the host: those at the base of the thallus and those on its surface. We determining the dissimilarity between the zones and the species involved. We identified 102 taxa of epiphytic macroalgae. There were significant differences between the two zones. In 31 hosts, the number of epiphytes was higher on the surface of the thallus, whereas the number of epiphytes was higher at the thallus base in 25 hosts, and the epiphytes were equally distributed between the two zones in five hosts (R=−0.001, p=0.398). The mean dissimilarity between the two zones, in terms of the species composition of the epiphytic macroalgae, was 96.64%. Hydrolithon farinosum and Polysiphonia atlantica accounted for 43.76% of the dissimilarity. Among macroalgae, the structure of the thallus seems to be a determinant of their viability as hosts for epiphytes.

Resumo em Inglês:

In the state of Paraíba, Brazil, there is an abundance of rocky outcrops, which are typical elements of the semi-arid landscape. Those outcrops provide refuge to species with morphological adaptations to stressful climates and to rare communities of plants, including bryophytes. Nevertheless, there have been no studies of bryophytes in such habitats in the state. Therefore, this work aimed to inventory bryophytes on two outcrops in the municipality of Puxinanã, in Paraíba, addressing some of the ecological aspects of survival in xerophytic environments. Samples were collected once every two weeks from February 2010 to May 2011. The usual techniques of bryophyte sampling and herbarium preservation were employed. We recorded 21 bryophyte species (six liverworts and 15 mosses), some of which are rare for Brazil. We performed cluster analysis, using the unweighted pair group method with arithmetic mean, based on the Sørensen similarity index. We thus defined three clusters among the studied outcrops and similar areas recorded in the literature. The rocky outcrops proved to be singular in terms of bryophyte species composition, which, as in most xerophytic environments, included light-demanding and generalist species, featuring various morphological adaptations to resist water stress, primarily in terms of their leaf structure. Our results demonstrate the urgent need for additional studies in the state of Paraíba, including floristic, conservation, evolutionary and biogeographic studies.

Resumo em Inglês:

We investigated antioxidant capacity, phenolic content and phytotoxic effects in seven species of fruit native to Brazil: Acrocomia aculeata, Hymenaea stigonocarpa, Tamarindus indica, Byrsonima intermedia, Psidium firmum, Myrciaria cauliflora and Ficus obtusifolia. Phytotoxic effects were assessed from crude ethanol extracts and semipurified fractions. In four of the seven fruits, total phenolic content, as determined by Folin-Ciocalteu assay, was higher in the peel than in the pulp. We found that total phenolic content correlated significantly with antioxidant capacity. High-performance liquid chromatography with diode array detection revealed the presence of the flavonoids quercetin and rutin in some fruits. We also evaluated the allelopathic effects of the crude ethanol extract and semipurified fractions. In most of the essays, the ethyl acetate fractions showed the highest level of activity.

Resumo em Inglês:

The species Vellozia sincorana L.B.Sm. & Ayensu is key to biodiversity conservation in the tropical mountain region of Brazil. The massive post-fire flowering of this endemic species provides a large, episodic supply of floral resources, mostly nectar, to animals.

Resumo em Inglês:

Everniastrum is a pantropical genus that has been recorded for the Brazilian states of Minas Gerais, Rio de Janeiro, São Paulo and Rio Grande do Sul. In this work, we present the first records of E. cirrhatum and E. vexans for the Brazilian state of Paraná. Comments and illustrations are provided.