Flowering phenology, seed set and arthropod guilds in Trichogoniopsis adenantha (DC) (Asteraceae) in south-east Brazil

and glades. This species blooms throughout the year, attracting arthropods of various guilds, including herbivores, pollinators and predators. In this study, done over a two year period, we described the phenology of T. adenantha and assessed the seasonal variation in arthropod numbers of different guilds. We also determined the periods of lowest and highest seed set. T. adenantha population showed a peak in flowering in March-April (rainy season) with greater production of achenes in December-April. April and October had respectively highest and lowest number of fertilized, undamaged ovules, and this pattern is possibly related with population dynamics of pollinators and herbivores. In August, which was the period of greatest damage to the stigma (by geometrid larvae), there was a positive relationship between the proportion of unfertilized ovules and flowers with damaged stigma, suggesting that floral herbivory may affect reproduction in T. adenantha. We discuss the complex dynamics of the beneficial and harmful interactions between arthropods and the host plant.

Distyly and variation in floral traits in natural populations of Psychotria ipecacuanha (Brot.) Stokes (Rubiaceae)

Psychotria ipecacuanha is a perennial, medicinal herb that grows in clusters in the understory of humid, shady areas of the Atlantic Rain Forest of southeastern Brazil. The present study characterized the variation in floral traits among 35 clusters from three natural populations of this plant species. Field observations showed that the clusters are isomorphic, that is, a given cluster will either set long-styled or short-styled flowers. Stigmas and anthers are reciprocally placed in each morph, a dimorphism characteristic of distyly. The populations are isoplethic, that is, a given population exhibits an equilibrium 1:1 ratio of floral morphs. Morphometric analyses revealed that anther length, stigma length, corolla diameter, and pollen grain diameter were consistently greater in short-styled flowers, regardless of the population investigated. Significant differences for floral traits in the short-styled morph were found among populations. Floral traits in the long-styled morph also showed some significant differences among populations, but not for stigma height and corolla length. Controlled pollinations carried out in natural populations showed that fruit production was higher after inter-morph pollination. Nevertheless, observations of pollen tube growth in style, and also fruit production after spontaneous self-pollination and intra-morph pollination, indicated partial intramorph compatibility in this plant species.

The site of self-incompatibility action in cupuassu (Theobroma grandiflorum)

Cupuassu (Theobroma grandiflorum (Willd. ex Spreng.) Schumann) is a fruit tree that is attracting attention in Brazil and also in other tropical countries. Its pulp is used to prepare ice-cream, juices, jellies and many other home-made sweets. This species has a very low fecundity, attributed to problems with pollination and self-incompatibility, noted as being restrictive to the agronomic productivity of the species. Controlled pollinations between compatible and incompatible parents were made and flowers were collected at three times: 24, 48 and 72 h after pollinations, during the floral seasons of 1995 and 1998. In flowers collected 24 h after pollination, in both compatible and incompatible crosses, around 70% of ovules showed egg apparatus without evidences of sperm cell delivery; nevertheless some pollen tubes had been observed. Ovaries collected at 48 h showed different behaviors according to the type of cross. In the compatibles, 35% of ovules did not show evidences of gamete fusion. In incompatible crosses this number rose to 50%. Collected ovaries with 72 h, from compatible and incompatible crosses, showed respectively 1.2% and 14.2% of the ovules with the egg apparatus and polar nuclei only. In these ovaries, for the two types of crosses, the presence of sperm nuclei was common and the zygote was still undivided. The incompatibility action is occurring after fertilization, in a late self-incompatibility action.

Nectar and pollen production in pumpkin (Cucurbita pepo L.)

Cucurbitaceae species depend on pollination by honey bees for fruit production. The overall objective of this work was to evaluate the potential of C. pepo for pollen and nectar production, that could help maintain colonies placed in the field. Plants of pumpkin were cultivated in field, in 1996 and 1997. Before anthesis, male flowers were covered to prevent visits by bees and other insects. After anthesis the flowers were uncovered and the following parameters were evaluated: 1) nectar production; 2) total sugar concentration in the nectar; 3) nectar replacement; and 4) production of pollen and flowers during the crop cycle. Nectar production varied from 18 to 79 µL flower-1 and increased progressively from 7h to 13h. The sugar concentration, measured at 7h, 9h and 11h, did not vary, averaging 50.5% ± 0.5% in 1996 and 40.5% ± 0.6% in 1997. At 13h the concentration decreased to 42% in 1996 and to 35% in 1997. Total daily nectar production was not influenced by removing nectar several times per day, indicating that nectar secretion is not stimulated or inhibited by frequent removal. The number of pollen grains did not differ in the two years, with an average of 43,669 ± 1,382 grains per flower. The peak rate of male and female flowers occurred from 60 to 66 days after planting (DAP) with 34.6 male flowers and 2.2 female flowers per plant, respectively. Cucurbita pepo has a potential for honey and pollen production of about 105 and 160 kg per hectare per season, respectively, which is enough to sustain, at least, five honeybee colonies.

Reproductive phenology of Melocactus (Cactaceae) species from Chapada Diamantina, Bahia, Brazil

This paper discusses the phenological strategies of Melocactus glaucescens Buining & Brederoo, M. paucispinus G. Heimen & R. Paul, M. ernestii Vaupel and M. ×albicephalus Buining & Brederoo, species from Chapada Diamantina, northeastern Brazil. Melocactus glaucescens, M. ernestii and M. ×albicephalus occur sympatrically in an area of "caatinga"/"cerrado" vegetation, and M. paucispinus in an area of "cerrado"/"campo rupestre". The superposition of flowering in these sympatric taxa was compared and analyzed. The phenology of M. paucispinus was correlated with both abiotic and biotic factors. Flowering of M. glaucescens and M. ×albicephalus were observed to be continuous (though with moderate peaks of activity), while fruiting was sub-annual. Melocactus ernestii exhibited an annual pattern of both flowering and fruiting; while in M. paucispinus the same patterns were sub-annual. These sympatric taxa showed 40% overlap of flowering periods, reaching to more than 50% in paired combinations of taxa, considering both the number of specimens flowering, as well as the quantity of resources being offered. Available information indicates that these taxa share pollinators, but phenological data rejects the hypothesis of shared pollinators and supports the hypothesis of hybridization in the study area. Rainfall was negatively correlated with flowering in M. paucispinus, but positively correlated with fruiting. Flowering of M. paucispinus in dry periods of the year avoids that erect flowers positioned in terminal cephalium, exposed in open areas of the vegetation, be damaged for the rains, while fruiting in rainy periods can be favorable to the dispersion and germination of this species.

Reproductive biology of the herkogamous vine Chiococca alba (L.) Hitchc. (Rubiaceae) in the Atlantic Rain Forest, SE Brazil

The family Rubiaceae comprises a wide spectrum of floral mechanisms and two of them seem to be common in certain groups, e.g., distyly in Rubioidae and styllar pollen in Ixoroidae. These mechanisms include herkogamy, which is interpreted as a strategy that avoids self-pollination. This is the first report on the reproductive biology of Chiococca alba, a species that is widely distributed in America. We studied floral biology and the mating system, which were evaluated through fruit set comparisons after controlled crosses (self- and cross-pollinations and test for apomixis), as well as through the evaluation of pollen tube growth resulting from these controlled crosses. Flowers of C. alba are herkogamous, cream, protandrous and lasted for two days. No measurable nectar was found, despite the presence of a nectary-like structure at the base of the corolla tube. Chiococca alba is a preferentially self-incompatible species, but self-pollination and apomixis also contribute to the natural fruit-set. Its reproductive strategy (herkogamy associated with protandry) is different from that expected for members of Chiococceae tribe (i.e., styllar pollen presentation).

A new species of Bulbophyllum Thouars (Orchidaceae) from Minas Gerais, Brazil

During the taxonomic revision of the Neotropical Bulbophyllum (Orchidaceae) species, a new species was discovered from Bom Sucesso, Minas Gerais State, described and illustrated here as B. hatschbachianum E. C. Smidt & Borba. This species belongs to the Neotropical section Xiphizusa (Rchb. f.) Cogn. and posses a lip epichile completely different from the related species. It is closely to B. plumosum (Barb. Rodr.) Cogn. due to its vegetative morphology, but has different flower size, color and lip epichile. In B. plumosum the epichile is thin, longer and wider than the hipochile. In B. hatschbachianum the epichile is fleshy, shortest than the hipochile, thin, and sharply narrower than the hipochile. The flowers of this new species is similar to the Mexican B. solteroi R. González, but the general morphology of the lip, trichome size and the geographical distribution clearly distinguishes apart the two species.

Floral resources used by insects in a grassland community in Southern Brazil

The goal of the present study was to identify plant species used as food source, the floral resources utilized, and the insects that visit flowers in a grassland community in southern Brazil. The study was carried out in an area of one hectare, located in a grassland formation in the Parque Estadual de Itapuã, State of Rio Grande do Sul, Brazil. The flowering pattern was seasonal, and richness and abundance of insects was higher during the period of high resource availability. Flowers of 106 species of angiosperms (73 genera and 34 families) were used as source of floral resources for 219 species (2,767 specimens) of insects. A total of 91.5% of plant species were visited by bees, 53.8% by flies, 34.9% by wasps, 22.6% by butterflies, and 12.3% by beetles. Nectar was the main resource consumed by the visitors (41.1%). Asteraceae was the richest (38 spp.) and most visited family, with 63.1% of the species and 49.5% of all specimens of recorded insects. Bees were the most representative insects (33.2% spp., 65% indiv.), followed by flies (26.9% spp., 16.5% indiv.), wasps, butterflies and beetles. 40 plant species were considered important resources for the floral visitors' community, due to high number of, both, species and individuals recorded in their flowers. The family Asteraceae as a species set was the main floral resource used by insect visitors through the year and has great importance for the maintenance of populations of many species of bees, flies, wasps and butterflies in the studied area.

Pollination biology in Jacaranda copaia (Aubl.) D. Don. (Bignoniaceae) at the "Floresta Nacional do Tapajós", Central Amazon, Brazil

Jacaranda copaia (Aubl.) D. Don is a pioneer tree widespread in the Brazilian Amazon, usually found colonizing forest gaps and altered areas, and the forest fragment edges. This study investigated aspects of the floral biology, breeding system and pollinators of J. copaia trees. Flowering lasts from August to November, during the low rainfall period extending up to four weeks per tree and 3-4 months for the population as a whole, characterizing a cornucopia flowering pattern. The fruit set ends in the beginning of the rainy season, with wind dispersed winged seeds. Fruit set from open pollination was 1.06% (n = 6,932). Hand pollination using self-pollen (n = 2,099) did not set fruits. Cross-pollination resulted in 6.54% fruit set (n = 2,524), representing six times more than the natural pollination rate (1.06%, n = 6,932). Flowers excluded from insect visitation (automatic self-pollination) did not set fruits (n = 5,372). Pollen tube growth down to ovary was detected under fluorescence microcoscopy in cross-pollinated and selfed pistils. The species is an obligate allogamous plant, with late-acting self-incompatibility system. Approximately 40 species of native bees visited the flowers, but the main pollinators were medium-sized solitary bees as Euglossa and Centris species due to the compatibility between their body sizes with the corolla tube, direct contact with the reproductive structures and high frequency of visits.

Synchrony is more than overlap: measuring phenological synchronization considering time length and intensity

The degree of flowering and fruiting synchronization is believed to have ecological and evolutionary relevance at several scales. Here we discuss some measures that have been used to estimate synchrony and propose an index that incorporates both the entire length of an individual phenophase and variation in the number of flowers or fruits over that time period. This new index describes more accurately the phenological synchrony among individuals and populations.

Reproductive biology and cytology of Hypericum brasiliense Choisy (Hypericaceae)

This is the first study of reproductive biology and cytology carried out with Hypericum brasiliense, a species with medicinal properties and potential agronomic interest. Three populations of H. brasiliense collected at Southeastern Brazil were studied. The results indicate that H. brasiliense is preferentially allogamous, self-compatible, facultative apomitic and anemophilous. Male sterility was observed in about 50% of individuals from the three populations. Anatomical studies evidenced structural abnormalities in anthers of male sterile flowers, showing enlarged tapetal cells and thick secretion deposits on the tapetal cell surfaces that may cause nutritional deficit for pollen mother cells. In cytogenetic studies several haploid chromosome numbers were observed like n = 4, 8, 9, 11, 16 and 17, including the presence of multivalents and micronuclei in tetrads, indicating the occurrence of abnormalities in the meiotic process of H. brasiliense. Despite these meiotic abnormalities the pollen viability and in vitro pollen germination rate observed in fertile flowers may be considered high. The diploid chromosome number 2n = 16 was observed, and the chromosomes in metaphase were small and similar. Fluorochrome staining techniques using DAPI and CMA3 were applied, with no positive bands observed.

Pollination and fruit set in pumpkin (Cucurbita pepo) by honey bees

Species of Cucurbitaceae are cultivated worldwide and are depend on bee pollination for fruit set. Field and lab experiments were conducted at Cornell University, Ithaca, NY, during 1996 and 1997 to determine "Howden" pumpkin (Cucurbita pepo L.) pollen removal and deposition by honeybees and factors relating to male flower attractiveness. Several parameters were evaluated in flowers at anthesis: (1) removal of pollen from anthers by honey bees, (2) pollen deposition on the stigma by honey bees, (3) amount of pollen on the body of honey bees, (4) fruit set after bee pollination, and (5) male flower nectary's pores and flower attractiveness. Honey bees carried between 1,050 to 3,990 pollen grains and 13,765 were removed from an anther after one visit. The amount of pollen deposited on the stigma by the honey bees varied according to the number of visits, from 53 grains with one visit, to 1,253 grains with 12 visits, and the mean number of grains in each visit varied from 53 to 230 grains. The percentage of established fruits was higher (100%) when the flowers received 12 visits of Apis mellifera, corresponding to a load 1,253 pollen grains. The attractiveness of the male flower for pollen and nectar collection was increased by the degree of opening of the access pore to the nectary in the flower.

Are there evidences of a complex mimicry system among Asclepias curassavica (Apocynaceae), Epidendrum fulgens (Orchidaceae), and Lantana camara (Verbenaceae) in Southern Brazil?

The goal of this paper was to test the presence of mimicry in Asclepias curassavica L., Epidendrum fulgens Brong., and Lantana camara L. The study was carried out at the Parque Estadual de Itapeva, RS, southern Brazil, from 2004 to 2006. Flowering period of each of the three species was followed up; focal observations of butterflies visiting flowers, from fixed point and during random walks were carried out. We also estimated the frequency of pollinaria removal in the orchid, as well as its mode of reproduction. All these variables were important for testing the mimicry hypothesis. Despite some temporal coincidences in the flowering period of two plants in the system, there was no statistical association among the three plants as to flowering period. Twenty-nine species of butterflies, as potential pollinators, were recorded, particularly Agraulis vanillae maculosa, Dryas iulia alcionea, Urbanus simplicius, Tegosa claudina, and Heliconius erato phyllis, which were the more frequent visitors of the three plants. There was association between the number of visits to L. camara and E. fulgens, based on Pearson correlation (r = 0.4603; n = 19; P = 0.0473). Pollinaria removal of E. fulgens was low, as measured by the percentage of removal (range: 0 - 10%). The analysis of the mode of reproduction of this orchid showed its pollinator-dependence, since no fruits were formed by spontaneous self-pollination. In contrast, the percentage of fruit set that resulted from geitonogamy and xenogamy was, in average, 86%. The results here shown are not conclusive as to the occurrence of a mimicry system among the three plants.

New species of Luxemburgia A. St.-Hil. (Ochnaceae)

Three new species of Luxemburgia named as L. furnensis Feres, L. leitonii Feres and L. mogolensis Feres are described and illustrated. A map with the geographical distribution of the new species is provided. Luxemburgia furnensis and L. polyandra A.St.-Hil., both from Minas Gerais, are similar in the absence of cilia on the leaf margin, but L. furnensis differs in the leaf shape, inflorescence and flowers size. Luxemburgia leitonii (also from Minas Gerais) differs from L. macedoi Dwyer (from Goiás) by the smaller flowers and absence of cilia at the margins of the bracts and bracteoles. Luxemburgia mogolensis (from Minas Gerais) resembles L. glazioviana (Engl.) Beauverd (from Rio de Janeiro) in the leaf, bracts and bracteoles shape, and differs by the presence of cilia at the sepals.

Flowering and fruiting of Aulonemia aristulata: a gynomonoecious woody bamboo species from Atlantic Forest in Brazil

Aulonemia aristulata (Döll) McClure is a lignified bamboo species endemic to Brazil. This species occurs in southeastern forests and can reach high density at forest edges, dominating the understory of canopy-disturbed forest patches. The goal of this study was to describe the flowering period, floral biology, fruiting and seedling recruitment of A. aristulata in natural conditions in two areas located in a segment of the Atlantic Forest. Data on the morphology of the synflorescences and florets, timing and sequence of the anthesis events and floral visitors were recorded. Natural pollinators (open pollination or control) as well as spontaneous self-pollination were also checked. Pollen viability was estimated using the acetocarmine technique. Aulonemia aristulata is monocarpic (semelparous) with gregarious flowering. All culms in both studied areas blossomed and fruited between August and November 2007, dying subsequently between December 2007 and April 2008. Two types of synflorescences and flowers were observed: terminal with bisexual and protandric florets, with the anthesis lasting for 3-4 days; and axillary, with morphologically bisexual, but functionally female, florets and anthesis lasting for 3-4 days. The latter were also observed in the rhizome of plants whose aerial portion had been removed. The presence of axillary synflorescences with pistillate flowers is described here for the first time in Aulonemia species. Moreover, this is the first report of gynomonoecy in woody bamboo. Fruiting from bisexual florets under natural conditions (35%) was superior to that obtained from bagged synflorescences (11.5%). Fruiting from functional female florets was around 20%. Pollen viability was on the average of 90%. The results suggest that Aulonemia aristulata is anemophilous. The massive bamboo seedling recruitment observed after dieback with the ability to colonize open areas could promote the regeneration of Aulonemia aristulata.