Biologia floral de Serjania paucidentata DC. (Sapindaceae).

Abstract

Serjania paucidentata DC (Sapindaceae) is a liana native to Brazil, often found in forest edge habitats, and able to colonize degraded areas, making it an important species in the initial stages of forest restoration. This study describes aspects of the floral biology of S. paucidentata using natural populations in post-mining forest restoration areas in Paragominas, Pará State, Brazil. Morphology and floral behavior were assessed on 16 individual plants. Marked open-pollinated flowers were observed from pre-anthesis to three days after anthesis, in order to characterize longevity and resource availability to pollinators. The size and appearance of the whorls in the floral morphs were recorded with the aid of a stereomicroscope and scanning electron microscope, and compared using Analysis of Variance, followed by the Tukey test. Stigmatic receptivity with an aqueous solution of hydrogen peroxide, sugar concentration (% brix) and nectar volume (μl) with the aid of a portable refractometer, and the presence of osmophores with neutral red solution, were tested in the field at different flower morphs and ages. The results show that S. paucidentata has inconspicuous (4-5 mm), white, functionally unisexual, zygomorphic, nectariferous and odoriferous Flowers. Anthesis begins at 3:00 a.m. with newly opened flowers senescing after 12 hours. During the study period, the thyrses of the marked branches had a temporal sequence of presentation of staminate-pistillate-staminate flowers, with no overlap of presentation between the morphs. Staminate flowers have rudimentary non-functional gynoecium, and morphologically bisexual flowers are functionally pistillate with indehiscent anther stamens. The flowers are tetrameres. The sepals are trimorphic and petals are dimorphic. The four petal appendages converge along the villose margin and form a floral pseudotube, where nectar accumulates, and have yellow crests that function as a nectar guide. In both floral-morphs, the reproductive structures are dislodged to the anterior part of the recptacle, and curved towards the appendage crests. Nectar production (0.6-1.2 μl) was recorded from anthesis to the third floral day, and was highest on the first day, with a sugar concentration between 40-60%. Osmophores are present mainly in the stigma of pistillate flowers and in the anthers and crests of petals of staminate flowers. At 12:00 a.m. the floral odor is soft, pleasant, noticeable, when there was an abundant and diverse visitation of bees, moths, flies, beetles, butterflies, wasps and hummingbirds. It was concluded that this species has a conspicuous and complex floral display, exhibits sexual dimorphism of the andromonoecious type, but functionally monoecious, with alternating presentation of floral morphs in the branches and individuals studied, indicative of the rare phenomenon of duodicogamy, which involves alternating sexual phases within of an individual.