Storage substances such as starch grains, proteins and lipids were studied during the male gametogenesis and in the mature pollen grain of Ilex paraguariensis St. Hil. (Aquifoliaceae). There are two cycles of amylogenesis and amylolyse. The first cycle lasts until the vacuolated stage when the starch is hydrolyzed and amorphous proteins are stored inside the single vacuole. The next cycle begins after mitosis with the formation of the vegetative and generative cells. At this point, the young veg
etative cell stores many starch grains that are bigger than in the first cycle. During the maturation of the male gametophyte, the starch is hydrolyzed and it is absent in the mature pollen grain. Small lipid droplets surround the young generative cell after the mitosis of the androspore and are dispersed in the vegetative cytoplasm during its maturity. The relationship between the pollen storage substances and the ontogeny of the layers in the sporoderm, formation of the generative cell, and the male germ unit were discussed.
The present study deals with the aspects of phenology, floral biology and reproductive system of Jacquemontia multiflora, a caatinga species at the Fazenda Catalunha, Santa Maria da Boa Vista - PE. The species is an annual liana, with cornucopia pattern of flowering. The peak of flowering occurs between the end of March begining of April at the end of the wet season. Its cymose inflorescences have the main axes elongated, exposing the flowers well out the foliage leaves. The blue flowers are sha
llow campanulate, scentless and producing a very low quantity of nectar. Anthesis is diurnal, the flowers beggin to open at around 05:30h., are ephemeral, lasting for about nine hours. The most frequent visitors are bees (Apidae and Halictidae). Apis mellifera and Trigona spinipes were considered the main pollinators of this species. J. multifora is facultatively autogamous, producing fruits either after self (30%) and cross (60%) manual pollination.
During the period from 1992 to 1997, interactions of several organisms and Ficus eximia figs, a monoecious species, were studied in plants located in Campinas/SP and Londrina/PR (Brazil). Ficus eximia is pollinated by a single fig wasp species, Pegoscapus sp. (Hymenoptera: Agaonidae, Agaoninae), but also visited by other 14 non-pollinating wasps (Agaonidae, Eurytomidae, Torymidae). Mites (Tarsonemidae), nematodes (Diplogasteridae) and fungi which use the body of the pollinating fig wasp to dispe
Anomalies of male gametophyte development was observed during anther development investigation in the clone CP76 of Anacardium occidentale. Androspores that stop development before the first pollen mitosis, and grains that show male gametophyte anomalies in early stage of development, was observed. The anomalous first mitosis generate two identical cells, or quite, or grains where cell plate was partially formed. Nuclear fusion occurs in those cells where partial cell walls were formed. The inte
rruption of development before first pollen mitosis occurs in high frequency, on the other hand, the anomalies related with the first pollen mitosis are very rare.
A study of the floral biology and the breeding system of Ferdinandusa speciosa Pohl (Rubiaceae) was carried out from March to September 1996 in Uberlândia, MG, central Brazil. This species is a shrub or small tree that occurs in swampy edges of gallery forests. The two studied populations flowered somewhat asynchronously from March to July. The tubular flowers are red, approximately 4.7 cm long and last for two days. They are protandrous and the pollen is available one day before the stigma beco
mes receptive. The beginning of anthesis and the opening of the stigmatic lips occur at dusk. The nectar is secreted during both the male and the female phases, with concentration of sugars greater in the male phase. The flowers are pollinated by two hummingbird species, Chlorostilbon aureoventris and Phaethornis pretrei. Ferdinandusa speciosa is a self-compatible, non-apomictic species, with low fruit production under natural conditions in the populations studied. No differences were found between fruit set of self- and cross-pollinated flowers, nor in the pollen tube growth rate in the pistils of these flowers. The seeds formed by cross-pollination are larger, heavier and show a higher percentage of germination than those formed by self-pollination, which indicates inbreeding depression. This result suggests that, although the species is self-compatible, cross-pollination may be advantageous.
The phenological patterns of trees from cerrado, savannah and others seasonally dry forest are not well known and causes for observed periodicity are still obscure; it is said to be caused either by abiotic factors like precipitation or to biotic ones or even both, or also enforced by phylogenetic restriction. In an area of cerrado in the far northeast of Maranhão, the ten most frequent leguminous trees were monitored during twenty-two months. The phenological records were made montly in a sampl
e of ten individuals of each species. Either vegetative or reproductive growth are periodical and seasonal events and in the most species flowering occur during the dry season simultaneous to leaves renewal. Most species produce fruits during the wet period and the propagules are dispersed almost exclusively during the dry one. Tree phenological patterns are discernible: species that renew their leaves and bloom early during the dry season, fruiting and dispersing their propagules at the same season (1), species that renew their leaves late in the dry season, flowering at this time (2) or flowering during the wet season (3), fruiting in the wet period and dispersing their propagules during the following dry one. Periods of vegetative growth and dormancy seem to occur alternately more synchronised with variation of the photoperiod, thermoperiod, and irradiance, than seasonal variations of water availability. Phenological patterns, flowering and fruting periods vary inter and intra families considered as monophyletic, being the only convergence, at this taxonomic level, the synchronisation of thepropagules dispersal in the dry season. The vegetative reproduction does not seem to be a common event in the leguminous species studied.
Octomeria crassifolia Lindl. and O. grandiflora Lindl. are myophilous, self-incompatible and partially inter-compatible species. In order to better understand the relationships between their reproductive systems, patterns of genetic variability, and isolation mechanisms in sympatric populations, a genetic study using ISSR molecular markers was carried out in natural populations growing in southeastern Brazil. The populations of both species demonstrated moderately high genetic variability greate
r than that observed in other self-compatible melittophilous orchid species, indicating that self-incompatibility may be a determinant factor in maintaining higher variability levels in myophilous Pleurothallidinae species. Contrary to what might be expected due to behavior of their pollinators of flying short distances, these species of Octomeria demonstrated relatively low genetic structuring that was probably related to gene flow by seeds or to older shared genetic stock. Bayesian analysis of genetic structuring indicated the presence of three genetic groups in O. crassifolia (although without any relation to their geographical distributions) and two genetic groups in O. grandiflora (with one of them restricted to one of the populations). No indications were seen of hybridization or introgression among the sympatric populations, indicating that pollinator specificity is an important factor in guaranteeing the identities of these inter-compatible species.
Floral biology and breeding system of Bauhinia forficata (Leguminosae: Caesalpinioideae), a moth-pollinated tree in southeastern Brazil. Bauhinia trees have a wide variety of pollination and breeding systems that are affected by geographic distribution. Bauhinia species with nocturnal anthesis are usually chiropterophilous and/or sphingophilous. B. forficata Link has floral features that are typical of the sphingophilous condition and this report describes the floral biology, pollination, and br
eeding system of a population of this species in a small fragment of semideciduous forest in southeastern Brazil. Flowers lasted 18 h, anthesis started at dusk, and pollen release and nectar production occurred at 8:00 and 10:00 pm, respectively. Flowers were protandrous and the stigma became receptive around 11:00 pm with the bisexual phase ending at 12:00 am. Nectar was produced continuously; the mean total nectar volume/flower was 15.11 μL and the mean total nectar concentration was 25.9 %. B. forficata is a strictly sphingophilous species that is pollinated exclusively by Manduca sexta L., the body morphology and behavior of which favor pollen transfer. Visitation by the bees Eulaema nigrita Lepeletier and Xylocopabrasilianorum L. (Apidae) occurred in the morning, but these species were considered occasional and not legitimate pollinators. Despite the geographic distance separating the Brazilian B. forficata from the Venezuelan B. aculeata, both species show very convergent pollination systems but differs in their faunal composition. B. forficata is homomorphic and predominantly self-incompatible; cross-pollination produces twice as much fruit as natural open pollinations, indicating a pollen limitation and relative inefficiency of the pollinator, the latter effect may reflect habitat disturbance that favors geitonogamous pollination and decreases the efficiency of pollination. More studies are necessary to investigate the relationship between habitat disturbance and geographic distribution on the pollination and breeding systems of Bauhinia species.
P. kingii is a monotypic genus within the Asteraceae family that grows under extreme environmental conditions and possesses an unusual single-flowered capitulum. It is endemic to Chapada Diamantina, Bahia, Brazil, a region dominated by a mosaic of rocky, sandy flats and bogs in the upper elevational zone (above 900–1,000 m). To gain a better understanding of the pollination biology of P. kingii, we examined its floral development, floral rewards, reproductive strategies, and floral visitors. The
flowers exhibit asynchronous diurnal anthesis with three distinct floral stages, each differing with regard to male–female maturation and nectar availability; these floral stages appear to influence the activity of the flower visitors. Although several floral characteristics of P. kingii suggest that it is an entomophilous species, observations revealed it as a generalist species for which hummingbirds and bees are the main floral visitors, differing slightly in the diurnal period of their visits. P. kingii can reproduce through xenogamy, geitonogamy, and what appears to be allogamy, but with different sizes of fruits (achenes) produced depending on the reproductive strategy employed. This study revealed some important features of pollination and floral biology within Asteraceae and provides clues for pollen dispersion in a harsh environment.
The species H. musciformis is one of the main natural sources of k-carrageenan, a polysaccharide widely used in the cosmetics, textiles and food industries. There are few phenological studies with natural populations of this species, especially in the northeast of Brazil. This study aims to contribute to the knowledge of the biology and ecology of H. musciformis in a tropical region of Brazil by analyzing its reproductive and phenological aspects. Two epiphytic populations of this species were a
nalyzed on the beaches of Stella Maris (Salvador) and Itacimirim (Camaçari), located in Bahia, Brazil. A total of eight sampling were made during the dry and rainy seasons from 2007 to 2009. The samples were obtained using transects (20 m) and square (0.04 m2) in three regions based on different reef hydrodynamics: tidal pool, protected reef region and front reef region. For statistical analysis, Fisher’s exact test was used with confidence level of significance for all tests set at 95 % (P = 0.05). No male specimens were observed and carposporophytes were rare during the study. The occurrence of infertile specimens was low, especially at Stella Maris. The tetrasporophytic phase was dominant in all sampled sites. The seasonality analysis showed higher percentage of samples in tetrasporophytic phase in Stella Maris, during the dry season, while in Itacimirim there were no differences between dry and rainy seasons. The phenology of algae could have been influenced by the interaction of abiotic and biotic factors, modifying their reproductive behavior according to environmental changes.
Quantifying the importance of pollinators for reproductive success of plants is a central question in reproductive biology. However, the literature contains a profusion of terms and sometimes conflicting definitions. This inconsistency is a barrier to broad comparisons and conceptual advances in different fields. In recent decades, some widely disseminated studies have proposed recommendations to foster greater standardization. Nevertheless, the literature continues with little uniformity, and t
erms such as “efficacy,” “efficiency,” and “effectiveness” of pollinators are still used inconsistently. Previous studies concerning conceptual and terminological uniformity provided a series of particular terms related to specific metrics and/or strict definitions for these widely used terms. I here propose comprehensive verbal definitions for the terms that have historically been used by most specialists. Pollinator performance in achieving reproductive success is defined here as its effectiveness, which is, broadly, given by the product of two components: pollinator efficacy and intensity of visitation. In some approaches, a third component – pollinator efficiency – is important for estimates of its effectiveness. The definitions suggested here apply to different variables, parameters, and procedures for study, and may refer to either individuals or populations of a pollinator species, or to functional groups of pollinators. This terminology can be applied widely, as it is not constrained by the scope, approach or scale of a study. A basic terminology with simple definitions may facilitate consistent use of these terms by specialists, particularly among younger investigators, thus surmounting the first barrier to future proposals for conceptual and methodological unification at larger scales.
This study was carried out aiming to characterize the different stages of androsporogenesis (meiotic) and androgametogenesis (post-meiotic), and analyze the relationship between the lengths of the flower bud and the anther in relation to the development stages of gametophytes in wild species of Passiflora of ornamental potential and interspecific hybrids F1, to generate subsidies for researches with anther culture and genetic improvement programs. Due to overlaps between the lengths of the buds
and anthers and the stages of meiosis I and II, the analyses have allowed only the differentiation of five different classes: prophase I, meiocytes with cells in metaphase I to telophase II, tetrad, androspores, and androphyte I. The use of the anther length was more indicated for differentiation between the androsporogenesis and androgametogenesis than bud length. The occurrence of symmetric binucleate androphyte was considered an anomaly in view of its low occurrence (lower than 7.5 %). There was no association between the different locations of anther sections and developmental stages of androgametogenesis, with overlaps between these variables.
Modern pollen–vegetation relationships are the basis for any paleo-study and are especially needed to understand fossil pollen assemblages and their ecological inferences. Some authors have proposed that lakes and ponds represent the surrounding vegetation through pollen grains captured by the lake. The aim of this work was to establish the modern pollen–vegetation relationships of coastal plant communities and pollen spectra represented in the surface sediments of a coastal shallow lake, and to
evaluate whether spatial heterogeneity was captured by the Lake Chaparral in Perla de Rocha, Rocha, Uruguay. Pollen grains of five surface sediment samples were analyzed and related with a stratified sampling of vegetation communities surrounding the lake. Correspondence analysis and t test were used to determine plant communities and analyze the diversity of pollen assemblages. Several plant species relevant to conservation were registered, and plant communities were differentiated: coastal forest, dunes, prairies, and wetlands. However, due to limitations in taxonomic identification level for the grains of graminoids (Poaceae, Cyperaceae) in pollen assemblages, herbaceous communities highly represented by these botanical families were inferred as open environments. Pollen spectra registered at Chaparral Lake represented local and nearby vegetation well, according to both old and new theoretical models of lakes as a catchment pollen system. Several pollen grains were good indicators of the coastal forest (Myrsine sp., Ephedra tweediana Fisch. & C. A. Mey., Lithraea sp. and Tripodanthus acutifolius (Ruiz & Pav.) Tiegh.), and dunes (Chenopodiaceae, and Ambrosia sp. and Senecio sp.). The modern pollen–vegetation relationship established in this work is similar to those registered for the southern coast of Brazil, due to a shared forest component in both vegetation and pollen spectra. These results constitute primary data for the area, and we think this system is very appropriate for the historic reconstruction of coastal vegetation, particularly the coastal forest.
This paper presents a palynological study of 14 Janusia species and seven species belonging Aspicarpa, Camarea and Cottsia to contribute to the taxonomic study of the Gaudichaudieae tribe. The pollen grains were examined under optical and scanning electron microscopy. The pollen grains are generally spheroidal or cuboidal, medium to large, 6-8-porate and display variable colpoids and ornamentations. Janusia pollen grains vary in their quantitative characteristics, apertures and ornamentation. In
some Janusia species, we observed the presence of a lipid substance on the pollen grains, likely pollenkitt. The pollen morphology of the cleistogamic flowers of Janusia guaranitica is clearly distinct from the pollen grains of chasmogamous flowers in all species analysed. Janusia anisandra, Janusia caudata and Janusia christianeae possess harmomegathic mechanisms, and the presence of colpoids also in J. guaranitica (chasmogamous flower) may suggest a direct relationship between these species, although their presence is more frequent in more humid areas. The results of palynological analysis suggest that the studied genera cannot be delimited using palynological characteristics but that they may be helpful to distinguish among genera.
This study characterizes the phenological behavior of the most abundant species of riparian vegetation (Pandeiros river, southeast Brazil) in a transition region of Caatinga and Cerrado biomes and relates its phenophases to climatic variables. Among the ten most abundant species of each five sites studied between August 2008 through July 2009, individuals were marked for phenological monitoring, totaling 31 species and 964 individuals. For each sampled individual, the presence or absence of repr
oductive and vegetative phenophases was recorded and related to the climatic variables of precipitation, temperature, and relative humidity. The period with the greatest amount of vegetative and reproductive phenological activity was in the dry season. Among the climatic variables, the vegetative phenophases were most correlated by temperature, while the reproductive phenophases were most influenced by relative humidity. The species studied presented phenological behavior similar to their typical occurrence area, like in cerrado and caatinga phytophysiognomies, contradicting the phenological pattern expected for riparian forest. However, this behavior also demonstrated adaptations for survival in a transitional environment, leading to the formation of a phenological pattern that is unique to the riparian forest studied.
Many species of wild passion fruit are used for the genetic breeding of passion fruit crop and kept in germplasm banks. This study investigated floral biology, breeding system, and chromosome number of Passiflora species that occur in areas of Cerrado in Uberlândia, Minas Gerais, from 2008 to 2010. In general, the species bloomed in the rainy season, the anthesis was diurnal, except for P. tricuspis, and flowers were open from 6 to 12 h. At the time of flower opening, the nectar was already accu
mulated in the nectariferous chamber. Protandry occurred only in P. tenuifila. Bees were the main flower visitors of these species. There were significant differences in the diameter and length of the floral androgynophore among species. Passiflora amethystina, P. tenuifila (both subgenus Passiflora), and P. suberosa (subgenus Decaloba) were self-fertile, while P. cincinnata (subgenus Passiflora) and P. tricuspis (subgenus Decaloba) were self-sterile, which contrasted with the usual trends in the group. The chromosome number for P. tricuspis was 2n = 12, P. amethystina and P. tenuifila were 2n = 18 chromosomes, and P. suberosa was 2n = 24 chromosomes, which conformed to the recorded results for the group. Overall conservative chromosome numbers, and self-fertility in P. amethystina are interesting results for breeding programs and basic information for conservation.
A pollen morphology study of 10 Brazilian native species of Fridericia (Bignoniaceae) from forest fragments was performed using light microscopy and scanning electron microscopy, in search of new characters that might increase knowledge of pollen morphology of the species, and also to help the taxonomic characterization of the genus. The pollen grains were acetolysed, measured, photographed, and described qualitatively. The quantitative data were analyzed by descriptive statistics and multivaria
te statistics. Non-acetolysed pollen grains were observed under scanning electron microscopy for further details of exine and pollen surface. The pollen grains are isopolar, medium to large, with circular to subcircular amb, oblate-spheroidal to subprolate, tricolporate, with long colpi, constricted or not, sometimes with margo, rounded or truncated at the polar ends, endoaperture lalongate, and microreticulate to reticulate exine, sexine thicker than nexine. The results indicate a stenopalynous genus, however, in some cases, it is possible to identify the studied species by the pollen morphology. Morphological considerations are also discussed.
This study aimed to elucidate the anatomy and morphology of extrafloral nectaries (EFNs) in Maprounea brasiliensis and whether environmental factors influence their traits of production and morphology. For this reason, we sampled leaves from individuals subjected to distinct fire and water regimes, and the anatomy and ultrastructures of EFNs as well as the chemical constitution of nectar were analyzed. EFN nectar production was associated with immature and recently expanded leaves. EFNs originat
e from the epidermis. At the end of ontogeny, secretory cells are surrounded by three or more layers of cells with secondary and lignified walls, isolating the EFN of vascular tissue. The ultrastructural analysis revealed mature EFNs with secretory activity. The experiments showed that EFN production was not influenced by the presence of frequent fires. However, during the rainy season, new produced leaves had nectaries in greater quantity and diameter than leaves produced during the dry season. The anatomical and ultrastructural changes demonstrated that nectar production is strongly influenced by the age of the nectaries which influence ant attendance to EFN since no ants were observed on leaves that did not secrete nectar. The seasonality experiment confirmed that EFNs of M. brasiliensis are resource dependent and evolutionary programed to appear in elevated number during the rainy season.
This study was conducted to estimate the amount of pollen produced by three entomophilous and two ornithophilous tropical woody taxa. It seeks to establish their reproductive success in relation to each other and contribution to the concentration of pollen in the air. The taxa selected were Bombax ceiba, Erythrina stricta (both ornithophilous), Lagerstroemia speciosa, Mesua ferrea and Schima wallichii (all entomophilous); which were studied in three different calendar years (2010, 2011 and 2012)
. M. ferrea produced the highest number of pollen grains per tree (3.85–6.60 × 1010) and B. ceiba highest number of pollen grains per anther (18,610 ± 1,189.49). The pollen grains produced were estimated to be about 100 million per tree in all the studied species except M. ferrea, which produced about 10 billion pollen grains per tree. There were both good and poor production years in all the studied species. During the course of the 3-year study, B. ceiba, E. stricta and S. wallichii produced maximum number of pollen grains per tree in the year 2011, whereas maximum pollen production was observed in M. ferrea in the year 2010. However, the 2 years (2010 and 2012) mass production was observed in L. speciosa. During the high pollen production years, the fruit setting was also recorded to be high. It is interesting to point out that in E. stricta, the fruit setting was 88.5 and 91.72 % higher (i.e. 39.12 ± 3.63 %) in the year 2011 as compared to the years 2010 (4.48 ± 0.63 %) and 2012 (3.24 ± 0.49 %), respectively.
Dioecious plant populations are composed of two distinct sexual morphs representing the female and male counterparts. Dioecy in restinga areas has been strongly associated with fleshy fruits, woodiness, generalist entomophily, and resource-poor environments. The ability of vegetative reproduction is another ecological trait commonly associated with dioecy, but not shown for the woody dioecious species in restingas. This study aimed to investigate whether the distribution of sexual morphs in popu
lations is due to occurrence of vegetative propagation as a reproductive strategy among dioecious woody species on sandy coastal plains. We also intended to evaluate possible effects of sex ratio on sexual reproduction (female reproductive success). The study was conducted in the sandy coastal plains (restinga) of Maricá, Rio de Janeiro State. We studied six woody dioecious species. During the reproductive period, all individuals of each species and your nearest neighbor were marked using GPS, along an area with approximately 5.1 ha. The sex of the individuals was recorded. This study provides evidence of the occurrence of vegetative propagation in the woody dioecious species studied and indicates that the ability to reproduce in this manner varies between sexual morphs, generating male-biased populations in most cases. Our data suggest that asexual reproduction by vegetative propagation of the male morphs can have an effect on sexual reproduction, as it increases the amount of staminate flowers, and therefore the supply of the pollen grains. Our results provide insights into vegetative reproduction as a strategy to increase male plant fitness and an alternative to populate environments under stress.
Dioecious species are dependent on pollen vectors for sexual reproductive success. Male and female plants can express different blooming strategies, which respectively favour pollen donation and reception. This study characterised the flowering phenology of ten dioecious species, with different floral resources and pollination systems. The study focused on an area of sandy coastal plain in southeastern Brazil. We evaluated flowering events of male and female plants, in addition to the distributi
on of species flowering periods over 2 years. Regardless of the dependence upon biotic pollinators, all species shared the following traits: a single or a more expressive flowering event per year, with a duration ranging from intermediate to long, a high percentage of activity and intensity and high synchronism rates for intra- and inter-sexual morphs. In most species, males flowered first and more intensely following a sex allocation perspective. The flowering periods of dioecious species were randomly distributed throughout the year, preventing the identification of phenological drivers. The results suggest that the biotic (floral resources, pollen vector), abiotic (temperature, precipitation, day length) and phylogenetic factors do not seem to explain the observed flowering strategies. Since the restinga is a geologically recent tropical environment, the phenological attributes of the dioecious species possibly reflect the individual patterns of colonising species more than it does the interactions among them and with the environment.
Tubular flowers are only found in two distantly related groups in Rutaceae: the mainly Australian tribe Boronieae and the Neotropical subtribe Galipeinae. It is assumed that these nectar-rewarded, tubular flowers arose from convergent evolution driven by pollinator pressures. However, there are few empirical studies on pollen vectors of Neotropical Rutaceae. We explored the floral biology and pollination of Conchocarpus rubrus (A.St.-Hil.) Bruniera and Groppo (Galipeinae), including details abou
t its nectar-secreting floral structures. We also compared the available records on floral biology and pollination of Boronieae and Galipeinae, aiming to provide a better understanding of the factors that influenced their floral evolution. Conchocarpus rubrus was pollinated by a single species of hermit hummingbird (Phaethornis idaliae Bourcier and Mulsant 1856) and by butterflies (Pyrginae and Pierinae), which take nectar accumulated at the bottom of the tube. Floral features and pollination data indicate that the convergent evolution of floral tubes in Rutaceae resulted from phenotypic specialization toward a subset of nectar-foraging pollinators with long mouth parts. Specifically, while in the Australian Boronieae the evolutive pathway toward sympetaly was likely influenced by Meliphagidae birds, in the Galipeinae, it was influenced by hummingbirds, butterflies, and settling moths. Besides a floral tube, floral features also linked to phenotypic specialization toward Meliphagidae pollination in Boronieae were related not only to birds’ attraction (nectar features, attractive colors, etc.), but also to insect impediments (sensory exclusion, absence of landing platforms, etc.), occurring together with other ornithophilous features. In Galipeinae, floral features are more diverse, and functionally linked to the different groups of pollinators herein found.
Nyctanthes arbor-tristis (L.) popularly known as ‘Parijat’ belongs to the family Oleaceae and is widely used in the traditional system of medicines in India. It has immense biological properties. In the present study, the shade-dried flowers were extracted in three different solvents such as ethanol, ethyl acetate, and water. The antioxidant activities were evaluated by four different in vitro assays—DPPH free radical scavenging, superoxide radical scavenging, lipid peroxidation, and reducing po
wer determination. Phytoconstituents like total phenolic and flavonoid content of the extracts were also measured. The maximum antioxidant activity was observed in ethanolic extract of the flower. The higher phenolic content was found in aqueous extract (177.0 ± 0.17 µg mg−1 gallic acid equivalent). Flavonoid content was higher in ethanolic extract 29.25 ± 0.13 µg mg−1 equivalent to rutin) of flower than the other two extracts. This indicates that both phenolic and flavonoid contents might be responsible for the antioxidant potential of the flower. Ethanolic extract of the flower was found most potent in antioxidant activity in all assays. Thus, the ethanolic extract of the flower can be used as a cheap natural source of antioxidants.
The pollen spectrum of 120 samples of Melipona (Melikerria) fasciculata Smith 1854 geopropolis from two phytogeographical regions of Maranhão, Brazil was analyzed. This study aimed to characterize the palynologically geopropolis produced by this species of bee. Samples were collected monthly in Palmeirândia (seasonally flooded fields vegetation) and Barreirinhas (“Cerrado” vegetation). A total of 121 pollen types were identified and distributed into 52 families and 84 genera. The predominant pol
len types (>45 %) were Adenocalymma inundatum (Bignoniaceae), Bauhiniareflexa (Caesalpiniaceae), Caryocar (Caryocaraceae), Chamaecrista (Fabaceae), Lafoensia (Lythraceae), Mauritia (Arecaceae), Machaerium (Fabaceae), Mimosapudica (Mimosaceae), and Ouratea (Ochnaceae). The pollen types Adenocalymma inundatum, Adenocalymma sp., Anadenanthera, Astrocaryum, Casearia, Caesalpinia, Caryophyllaceae, Cecropia, Crotalaria, Croton, Cydista aequinoctialis, Desmodium incanum, Drymaria, Euphorbia, Eupatorium, Eugenia, Ficus, Gustavia, Lecythidaceae, Malphigia, Maytenus, Mimosa verrucosa, Moraceae, Neptunia, Opuntia, Protium, Piptadenia, Pontederia, Polygonum, Schinnus and Wulffia were exclusive to samples from the seasonally flooded fields vegetation (Palmeirândia), whereas Acacia, Amaranthus, Arecaceae, Banara guianensis, Bauhinia guianensis, Bignoniaceae, Borreria latifolia, Byrsonima, Bromeliaceae, Cupania, Dalbergia, Fridericia, Galactia, Irlbachia, Malpighiaceae, Maytenus ilicifolia, Miconia/Tibouchina, Myrtaceae, Ouratea, Parkia, Pavonia, Picramnia, Phyllanthus, Securidaca, Stryphnodendron, Scrophulariaceae, Rourea, Tiliaceae, Trema, Xyris, and Wedelia were exclusive to the “Cerrado” vegetation (Barreirinhas). Some of these species are resin producers. The palynological analysis of M.fasciculata geopropolis from the state of Maranhão was valuable for the phytogeographical characterization of the samples, and it provided knowledge on the botanical origin of the resin.
Fire is considered a major factor in the succession process in “Cerrado”, determining the dynamics and composition of these Neotropical savanna plant formations. However, when savannas are protected from fire, both fire-tolerant and fire-sensitive plant species increase in density and size, especially species of trees. Nevertheless, how this change in the vegetation structure relates to changes in the ecosystem function has been seldom evaluated. Pollination is a major ecosystem service, and her
e we aimed to determine possible changes in floristic composition, floral biology, and pollination systems in an area of open savanna protected against fire over a period of 20 years in Minas Gerais state, Central Brazil. The comparison over the two decades showed that ecological succession, in the absence of fire, increased the diversity and decreased the dominance of plant species. There was an increase in specie richness from 156 spp. in 1992 to 206 spp. in 2012, with appearance of trees and species with specialized pollination systems. Plants were predominantly pollinated by bees in both periods, but floral diversity and specialization seem to have increased after fire suppression, for instance, with the emergence of more species pollinated by moths. Not only generalist light-colored actinomorphic flowers, but also tubular or cup-like nectar flowers commonly associated with more specialized pollinators predominated in both periods. The dominance of these contrasting features actually increased after two decades, especially when we compare the number of individuals in each group. However, it seems that the increase in plant diversity and density of woody species did not lead to marked specialization of floral features and pollination system along the studied period.
Inducement to stamen movement by oligolectic bees has been reported for some Loasaceae species; however, detailed research studies on the pollination ecology of species in the genus Aosa are absent. In this study, we analyzed the floral biology and breeding system of Aosa rupestris (Hook.) Weigend, focusing on the role of pollinators in inducing stamens’ movements. We described the anthesis, the behavior of floral visitors, and carried out reproductive experiments in a population in a dry forest
(“caatinga”) area in Northeastern Brazil. We carried out four experiments and one control to establish whether the interval between the movements of two successive stamens is regulated by pollinator visits. Anthesis lasted for 3–4 days. Stamens (102 ± 12.57) remained with closed anther inside petals early in the anthesis, after which they moved to the center of the flower and presented its pollen (male phase). After all stamens have reached the center of the flower, the female phase started. Bicolletes nordestina Urban, 2006 was the only floral visitor to A.rupestris flowers, drinking nectar, collecting pollen, or sleeping on the flowers. Aosarupestris was autogamous, but fruit set was higher under natural conditions. The interval between movements of two successive stamens was not different among experiments. Therefore, stamen movements were spontaneous and did not respond to pollinator visits, in contrast to the pattern of stamen movements observed in other Loasaceae species. Although A. rupestris is autogamous, floral structure and behavior of the oligolectic bee pollinator ensured the highest level of fruit set in this species.