We analyzed the flowering, fruiting and the pollination biology of two species of Marantaceae: Ischnosiphon gracilis (Rudge) Koern. and Stromanthe porteana A. Gris. Observations were carried out in natural populations at the "Parque Estadual Dois Irmãos" (8º7'30" S and 34º52'30" W), a remnant of Atlantic forest in Pernambuco. We verified a continuous phenological pattern in both species, with different flowering and fruiting peaks. Inflorescences of I. gracilis produced 14.4 ± 3.4 flowers and 1.3 ± 0.6 fruits whereas S. porteana produced 125.4 ± 14.8 flowers and 7.4 ± 4.9 fruits. We verified low pollen/ovule ratio and reduced fruit set under natural pollination for the studied species. Sugar concentration in the nectar of I. gracilis flowers was high (26%-32%), characteristic of bee flowers, and in S. portena the nectar was less concentrated (20%), common to hummingbird flowers. Ischnosiphon gracilis is pollinated by three species of Euglossini bees (Euglossa sp., Eulaema bombiformis and E. cingulata), whereas S. porteana is pollinated by one species of Euglossini bee (Eufriesea surinamensis) and two species of hummingbirds (Phaethornis ruber and Amazilia versicolor). The differences between the flowers of these species avoid the sharing and competition for pollinators, which can assure their maintenance in the habitat. However, in a long term, the low fruit set can affect the population structure by decreasing the reproductive success of these species.
Euglossini; Ischnosiphon gracilis; melittophily; ornithophily; Stromanthe porteana
