Biologia floral de duas especies sincronopatricas de Prestonia (Apocynaceae)

AUTOR(ES)
DATA DE PUBLICAÇÃO

1991

RESUMO

Observations on floral biology, breeding systems and pollination of Prestonia coalita and P. riedelÚ were carried out from January to April1989 and 1990. The study was undertaken in the Santa Genebra Forest Reserve, Campinas, São Paulo. Prestonia coalita has tubular flowers measuring 11 to 13mm in length. The color is yellow and the odour acrid and sweet. The stames are epipetalous, included in the corolla tube and located above the stigma. The stigmatic head presents two regions separated by a rim. The upper region is sterile and produces adhesive, and lower part is receptive. Nectar is produced in larger quantities at the base of the floral tube. Sugar concentration average 17% , varying from 12 to 20%. Flowers of P. riedelii are yellow in color, with some yellow-bronze parts. The odour is sweetish and the morphology is similar to that of P. coalita, but the tube is slightly longer. Nectar is produced in lesser quantities than in P. coalda; sugar concentration averaged 40% and ranged from 30 to 64%. P. coalz"taand P. riedelii are allogamous. Since there is a spatial segregation between the sexual organs, spontaneous self-pollination does not occur. Moreover, hand self-pollinated flowers do not developed fruits. However, in self-pollination experiments, pollen tubes were observed growing through the style and reaching the ovules. Probably these Prestonz a species have some kind of "late-acting self-incompatibility" mechanism. The flowers of P. coalita were visited by bees and butterflies. The bees Epichan s obscura and Euglossa sp. were the must frequent visitors and main pollinators.The butterfly Astraptes fulgerator, however, was the most frequent visitor to P. n edelÚ, effectively pollinating its flowers. Visits by Euglossa cordata, Euplusia vz olacea and by other butterflies were also recorded on flowers of P. riedelii. These two species of restonia present common traits associated with melittophily and psychophily syndromes

ASSUNTO(S)

ecologia ecologia vegetal botanica

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