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ABSTRACT Plant-pollinator interactions and their reproductive implications are of central importance to the organization of plant populations and communities in restoration areas. We studied the breeding system and flower visitors of Pleroma trichopodum, a pioneer species of the Atlantic Forest. We attempted to answer three questions: (1) Is P. trichopodum dependent on pollinators and mates for reproduction? (2) What are the pollinators of P. trichopodum? (3) Do tree flower-density and flowering-tree density of P. trichopodum enhance the visitation rate of focal trees and their flowers? We tested the breeding system through pollination treatments. We performed focal observations on 10 trees and analyzed the relationship between tree and flower visitation rates, and the tree flower-density and flowering-tree density with Generalized Linear Mixed Models (GLMM). Pleroma trichopodum sets fruits by selfing and outcrossing, both of which occur only through pollinator visits. Bees visited P. trichopodum, and their visitation increased with tree flower-density. Thus, individuals with greater floral displays may function as magnet species, enhancing the pollination of nearby plant species. This characteristic, allied with the ability to reproduce without a mate (selfing) and a tolerance of soggy soils, make P. trichopodum a candidate for Atlantic Forest restoration.

ABSTRACT Nectar production has an important role in pollinator attraction and successful fruit production in many self-incompatible angiosperm groups. The reproductive biology of Passiflora actinia was studied here and related to nectar dynamics. Passiflora actinia presented a temporal segregation of male and female functions at the beginning of anthesis. Due to the movements of floral verticils, the anthers were positioned in a way that favors pollination two hours before the stigmas reached the same position. The nectary consisted of an epidermis with stomata and a parenchyma rich in starch, which was hydrolyzed during anthesis. The nectary organization is probably associated with the continuous production of nectar during anthesis as well as with the high mean nectar concentration. Hand pollination tests indicated that Passiflora actinia is obligately xenogamous, depending on large bees for pollination, specifically the carpenter bee Xylocopa augusti. The continuous production of nectar may increase the number of bee visits, thus favoring pollen flow.

The abundance and distribution of resources for pollinators modulate the reproduction of plants. This study attempted to determine whether and how the fruiting success of Tibouchina trichopoda flowers varies due to plant size, number of flowers produced, distance between individuals and cardinal orientation of the flowers. From July 2009 to February 2010, we conducted monthly evaluations of 21 plants in an area of regenerating forest within the Atlantic Forest biome, located near the municipality of Antonina, in southern Brazil. Floral density was monitored weekly. During the study period, the species bloomed twice: once during the cool, dry season, showing an extended flowering period with scattered flowering individuals; and once during the hot, rainy season, showing a brief flowering period with a high density of flowering individuals. Plant size was not found to influence fruiting success. There was greater production of flowers and fruits during the brief flowering period. The extent of the floral display positively affected the fruiting success of the flowers, the effect being greater when the density of flowers was low and tending to stabilize at higher densities. The northern-facing portions of tree crowns produced more flowers and therefore had greater fruiting success than did the southern-facing portions. However, the proportion of fruits produced per flower was the same.

ABSTRACT Plant size and clonality are important traits for explaining the reproductive effort of clonal plants. Larger plants can invest more resources into reproduction, and clonality is known to increase reproductive effort. Moreover, reproductive effort is influenced by environmental variation, and so the spatial distribution of plants may affect plant reproductive effort. We investigated the effect of plant size, clonality and spatial distribution on the reproductive effort of Vriesea carinata in the Atlantic Forest in the state of Paraná, Brazil. We marked twenty individual plants and measured their rosette size, biomass and number, as well as rosette reproductive effort (number of flowers, fruits and seeds). We also evaluated the relationship between reproductive effort and spatial distribution of plants. Reproductive effort did not correlate with size, whereas greater clonal growth contributed to a lower reproductive effort because rosettes within clones that had more rosettes set fewer flowers. We found that plants growing closer to each other exhibited similar reproductive efforts independently of vegetative traits, because reproductive traits were spatially autocorrelated. In Vriesea carinata, the main drivers of reproductive effort are clonality, which decreases flower production, and spatial factors, which result in greater similarity in reproductive efforts among more proximate plants.

A atividade dos polinizadores é afetada pela disponibilidade de recursos. Flores que produzem mais néctar podem ser mais visitadas e assim apresentar maior produção de frutos. O efeito da produção de néctar na atividade dos polinizadores foi testado em duas espécies cultivadas de maracujá, Passiflora alata Curtis e Passiflora edulis Sims, em Morretes, Paraná. Botões foram ensacados e o néctar acumulado das flores foi coletado em intervalos de 1 h. Em P. alata o volume e a concentração de solutos no néctar aumentaram durante o período de antese, associados com o aumento da temperatura. Em P. edulis, o volume aumentou durante o período diurno da antese, e decresceu após as 18 horas. A concentração de solutos no néctar permaneceu constante. A taxa média de visitação de Xylocopa frontalis (Olivier) em P. alata foi de 1,7 visitas/100flores/hora e em P. edulis foi de 6,6 visitas/100flores/hora, sendo constante durante a antese. A taxa média de visitação de Bombus morio (Swederus) em P. alata foi de 5,8 visitas/100flores/hora, sendo mais alta no início da antese. A constância das visitas de X. frontalis deve estar associada à produção contínua de néctar em ambas as espécies de maracujazeiros. Como as espécies são xenogâmicas, a manutenção das visitas é importante para propiciar o fluxo de pólen entre indivíduos e assim garantir boa produção de frutos.Pollinator activity is affected by resource availability. Flowers that produce more nectar are visited more, which results in a greater fruit set. The effect of nectar production on pollinator activity was tested in two cultivated species of passion fruit, Passiflora alata Curtis and Passiflora edulis Sims, in Morretes, Paraná. Flower buds were bagged and the accumulated nectar of flowers was collected hourly. The volume and concentration of nectar of P. alata increased during anthesis, which was associated with rising temperatures. The volume of nectar of P. edulis increased during the diurnal period of anthesis, falling after 6 pm. The nectar concentration was constant during anthesis. The visitation rate of Xylocopa frontalis (Olivier) was constant for P. alata (1.7 visits/100flowers/hour) and for P. edulis (6.6 visits/100flowers/hour). The visitation rate of Bombus morio (Swederus) for P. alata was 5.8 visits/100flowers/hour, and was higher at the beginning of anthesis. The constant rate of visits by X. frontalis may be associated to the continuous nectar production by both species of passionflower. Since both species are xenogamous, the maintenance of visits during anthesis may favor pollen flow among the individuals assuring good crop production.

Reproductive biology, including phenology, flower biology, pollination, and the reproductive system in the bromeliad Aechmea distichantha were studied in an Araucaria forest in the state of Paraná. Phenology and reproduction in terricolous plants were followed in October 2006 and May - October of 2007. Flowering peaked from June to September and fruiting was from June to October. Flower anthesis lasted one day. Flowers were pollinated the most by the hummingbird Stephanoxis lalandi and the most common butterfly visitor was Lychnuchoides ozias ozias. Nectar concentration declined during anthesis, while nectar volume was constant. Aechmea distichantha is self-compatible with 30-45% fruit formation in self-pollination tests. Sunlight influences reproduction: when controlling for bromeliad and inflorescence size, plants in sunlight produced more seeds per fruit than plants in the shade. Reproduction was also associated with inflorescence size when controlling for bromeliad size. That is, larger inflorescences in similar sized plants produced more flowers and more seeds per fruit.A biologia reprodutiva, incluindo fenologia, biologia floral, polinização e sistemas reprodutivos foram estudados em Floresta com Araucária no Paraná. A fenologia e reprodução de plantas terrícolas foram acompanhadas em outubro 2006 e de maio a outubro de 2007. O pico de floração ocorreu de junho a setembro e a frutificação de junho a outubro. A antese durou um dia. As flores foram polinizadas principalmente por Stephanoxis lalandi e a borboleta mais freqüente foi Lychnuchoides ozias ozias. A concetração de nectar declinou durante a antese, enquanto que o volume de néctar permaneceu constante. Aechmea distichantha é auto-compatível com 30-45% de frutificação nos testes de autopolinização. A luz solar influenciou a reprodução: quando controlados o tamanho das bromélias e das inflorescências, plantas no sol produziram mais sementes por frutos que plantas na sombra. A reprodução também foi associada com tamanho das inflorescências quando controlado o tamanho da bromélia. Inflorescências maiores em plantas de mesmo tamanho produzem mais flores e mais sementes por fruto.