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Plant phenophases can be modulated by abiotic factors as well as by evolutionary history. We tested the influence of factors shaping the reproductive phenology of 17 co-occurring Piper species in a semi-deciduous seasonal forest in southeastern Brazil over a 12 month period. We describe the phenology, applying circular statistics to the flowering and fruiting phenophases for each species. Mantel correlation tests were conducted to investigate the role of phylogeny in phenological responses, and the influence of abiotic variables (temperature, rainfall, and day length) was analyzed using generalized linear models. Additionally, we tested whether the presence of latent flower buds influenced flowering and fruiting times. The phenological variation across species of Piper in the reproductive stages was not phylogenetically structured. Flowering and fruiting occurred throughout the year, but higher seasonality was detected in the flowering phase, which positively correlated with long days (∼13 h). The flowering phase was shorter and occurred earlier in Piper species with latent flower buds than in species without them, probably because these species are better adjusted to respond when climate conditions are favorable for flower anthesis. Thus, abiotic factors and the presence of latent flower buds shape the reproductive phenology of Piper species.

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Premise of research. Dichogamy is a common feature in early-divergent angiosperms, as in Piper, and is related to the effectiveness of pollination. To better understand the sexual reproduction in Piper species, we determined whether there is a pattern of pollen release and stigmatic exposure in Neotropical species of this genus, independent of flower sexuality and the number of stamens and carpels. Methodology. We studied 16 Neotropical Piper species, which have flowers with different numbers of stamens and carpels. We analyzed the floral events, in the field and in the laboratory, from bud to senescent flowers. Pivotal results. Twelve species had only bisexual flowers, and four species had bisexual plus staminate flowers. The bisexual flowers of all the analyzed species showed incomplete protogyny: the pistillate phase of flowers lasted from 2 to 7 d, and the bisexual phase lasted from 1 to 9 d. The stigmas were long-lived (4-16 d), and the stigmatic papillae were exposed sequentially and gradually in a basipetal direction, regardless of the number of carpels in the flower. Anther dehiscence was asynchronous and sequential, occurring in one stamen at a time, regardless of the number of stamens and flower sexuality. Conclusions. The dynamic of floral events (sequential and gradual exposure and senescence of stigmas in a basipetal direction, and asynchronous and sequential pollen release) suggests a pattern for Neotropical Piper species, considering that the analyzed species belong to different clades of the genus. In addition, these characteristics may also represent a pattern for the genus as a whole, as the floral development and morphology of bisexual and unisexual flowers are similar.

In tropical savannas, such as the campo cerrado in Brazil, fire plays an important role, affecting plant species' life history. Since fire has the potential to modify the structure of savanna communities as a whole, it is expected that it may influence the resource supply for mutualists by altering the pattern of investment in sexual reproduction. We used an experimental approach to test if fire alters trophic resource availability to pollinators (nectar, pollen, and oil) and seed-dispersing frugivores (fleshy fruits) by altering the seasonality of reproductive phenophases in a savanna community. We sampled all individuals of 60 species that were common to both control and experimental fire treatments. Each month we recorded the number of reproductive individuals to test whether fire affected the temporal resource offered by the plant assemblage as a whole, and by each specific plant group supporting distinct groups of pollinators and seed-dispersing frugivores. We noticed that fire advanced the nectar, pollen, and fleshy fruit offered by the whole assemblage. Additionally, fire affected the temporal pattern of nectar and pollen available to various pollinator groups, and of fleshy fruits available to all seed-dispersing frugivores. In general, fire seems to have a neutral or even a positive effect on resource availability to mutualists. Nevertheless, there were differences in the availability of the resource utilized by each guild of mutualists. Keywords Cerrado Á Fire Á Flowering Á Fruiting Á Mutualism Á Phenology Communicated by Michael Lawes.

The co-occurrence of some species, including members of the Piper genus, has been shown to be associated with phenological factors. In the present study we analysed vegetative (sprout production and leaf flush) and reproductive phenophases (spike production, flowering, spike abortion, fruiting and dispersed spikes) of the co-occurring species Piper gaudichaudianum Kunth and Piper vicosanum Yunck. and checked the influence of abiotic factors on their phenological behaviour. Our study addressed natural populations in a semi-deciduous seasonal forest in south-eastern Brazil. In both species, the phenophases occurred mainly in the rainy season, were seasonal and associated with environmental variables, especially day length. However, sequential flowering and fruiting isolated them temporally from each other. Other differences were the growth of sexually reproductive sprouts (45.7% of the total sprouts) and the production of latent spikes in P. vicosanum; in P. gaudichaudianum, only 7.1% of the sprouts produced spikes that were not latent. Spike abortion was high: 73.8% (n = 474) in P. vicosanum and 84.8% (n = 231) in P. gaudichaudianum. The remaining spikes with fruits dispersed, on average, 293 and 1168 seeds per spike respectively. Although annual phenological behaviour of the species is regulated by similar environmental variables, their distinct reproductive strategies seem to favour the maintenance of the co-occurring populations.

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The gradual and sequential exposure of stigmatic papillae in P. vicosanum flowers is described here as the mechanism for the long duration of receptivity. Anther development and pollen release were also sequential. These findings are yet unreported reproductive characteristics of the genus and offer new perspectives for future studies on the floral biology of other Piper species.