Fenologia Da Floracao, Estrategias Reproductivas E Polinizacao De Especies Simpatricas Do Genero Byrsonima Rich (Malpighiaceae)

Flowering phenology, pollination and reproductive strategies were studied in seven species of Byrsonima (B. coccolobifolia, B. crassa, B. guilleminiana, B. laxiflora, B. subterranea, B. wnbellata and B. verbascifolia) which occur sympatrically in cerrado (savanna-like) vegetation of the Fazenda Agua Limpa/FAL, of the University of Brasilia. Six species flowered sequentially during the dry season (May-October) with overlapping, and one species (B. laxiflora) flowered during the wet season (November-January). All species showed the Cornucopia type flowering pattern, with a great number of displayed flowers during several weeks. Byrsonima guilleminiana and B. subterranea are shrubby species while the other are treelets or trees. The flowers are in terminal racemes, with oil glands at the base of the calyx, the corolla is yellow, except for B. coccolobifolia and B. umbellata (pinkish-white). Anthesis is diurnal, pollen is shed before anthesis and the stigmas are contaminated during anthesis. The main vectors of pollination were bees of medium, and large size, of the genera: Centris, Epicharis and Bombus, being also frequent small bees (Trigona, Apis, Tetragona, Augchloropsis, Paratetrapedia and others). Byrsonima laxiflora was the most visited species, including wasps. All species demonstrated some level of self-compatibility. Fruit production (from selfing) was higher in the shrubs than in the trees. However, because the strategies and rewards (pollen and oils) encountered in flowers of Byrsonima and because of the large spectrum of hymnoptera which visited the flowers, it is suggested that these species are adapted to outcrossing

Breeding biology and distyly in Palicourea rigida H. B. & K. (Rubiaceae) in the Cerrados of Central Brazil Biologia reprodutiva e distilia em Palicourea rigida H. B. & K. (Rubiaceae) em Cerrados do Brasil Central

Distyly is a floral polymorphism more common among the Rubiaceae than in any other angiosperm group. Palicourea rigida is a typically distylous species of the Rubiaceae widely distributed in the Brazilian Cerrados. This work aimed to study the floral biology and breeding system of P. rigida in order to verify if there wasasymmetry between floral morphs. The work was carried out at Fazenda Água Limpa, Brasília-DF, from 1993 to 1995; and at Serra Caldas Novas State Park-Goias and in Clube Caça e Pesca Itororó de Uberlândia-Minas Gerais in 2005 and 2006. Density, height and pin/thrum ratio were assessed for flowering individuals in all areas. Plants were investigated for differences in floral morphology, nectar production, reproductive success and site of self incompatibility reactions. Blooming period was long and concentrated during the rains. Flowers were clearly distylous and with reciprocal herkogamy. They produced nectar and lasted for a single day. In spite of differences in density and height, populations were mostly isoplethic. Nectar production varied in volume and concentration but the differences could not be associated with floral morphs. The species is self-incompatible but reproductive success was always high and independent of floral morphs. There were differences in the site of incompatibility barriers between floral morphs, which were similar to those observed for other Rubiaceae. The main floral visitors and pollinators were the hummingbirds Colibri serrirostris and Eupetomena macroura. High fruit-set indicates that the pollinators transported enough compatible pollen grains between floral morphs, despite their territorial behavior.A distilia é um polimorfismo floral mais freqüente entre as espécies de Rubiaceae do que em qualquer outro grupo das Angiospermas. Palicourea rigida é uma espécie de Rubiaceae, amplamente distribuída nos cerrados brasileiros e em outras áreas de savanas neotropicais. O presente trabalho buscou estudar a biologia floral e reprodutiva de populações de P. rigida comparando as características associadas à heterostilia e a ocorrência de assimetrias entre os morfos florais. O trabalho foi realizado na Fazenda Água Limpa, Brasília, entre 1993 e 1995; no Parque Estadual da Serra de Caldas Novas-GO e na RPPN do Clube Caça e Pesca Itororó de Uberlândia-MG em 2005 e 2006. As populações foram caracterizadas quanto à densidade, altura e razão entre morfos dos indivíduos floridos. Foram investigadas diferenças na morfometria, produção de néctar, sucesso reprodutivo e reações de incompatibilidade. A floração foi longa, praticamente durante toda a estação chuvosa. As flores eram claramente distílicas e com hercogamia recíproca, apresentaram néctar como recompensa e duraram apenas um dia. Apesar de diferirem em densidade e altura dos indivíduos, as populações foram predominantemente isopléticas. A produção de néctar variou em volume e concentração, mas não foi associada a cada um dos morfos. A espécie mostrou-se marcadamente autoincompatível, mas o sucesso reprodutivo foi sempre alto e independente do morfo floral. Houve diferença nos locais de formação das barreiras de incompatibilidade semelhante ao observado para outras Rubiaceae. Os principais visitantes florais e polinizadores foram os beija-flores Colibri serrirostris e Eupetomena macroura. A alta produção de frutos indica que os polinizadores efetivamente transportaram quantidades suficientes de grãos de pólen compatíveis entre os morfos, apesar de comumente apresentarem comportamento territorial