Desenvolvimento floral de Parkia multijuga e Stryphnodendron adstringens, espécies andromonoicas de Leguminosae (Mimosoideae)

Abstract

Flowers and flower buds of various sizes were collected and processed for observations in scanning electron microscopy (SEM) and light microscopy (LM). The development of floral organs begins with the emergence of five sepal primordia in the floral meristem from the abaxial side (P. multijuga) and from the adaxial side (S.adstringens) in which in some buds, a sixth primordia arises late; five petal primordia simultaneously in P. multijuga and bidirectionally in S. adstringens, a carpel primordium emergence concomitantly to five antesepalous stamens primordia in P. multijuga, and after the petal formation in S. adstringens, and five antepetalous stamen primordium. In the final stages of the development, the stamens initiated in two whorls, one outer (antesepalous) and the other innermost (antepetalous), are arranged in a single whorl. However, the antesepalous stamens, which emerged first, are a little more elongated than the antepetalous ones. In P. multijuga the fillets join in the base while its elongation, forming a tube, which thereafter becomes adnate to the petals. In hermaphrodite flowers, in both species, the carpel primordium emerges, stretches, the carpel cleft closes and, soon after, the style begins its differentiation. In staminate flowers, the carpel primordium begins and stretches, but the carpel cleft does not close and the carpel does not end its development. In the mature stage, the hermaphrodite flowers present fully differentiated stigmas, while in the staminate flowers, the carpel primordium remains as a rudiment at the base of the bud. In this case, there is no initiation of any ovule. We conclude that staminate flowers in both species arise by carpel abortion and not from inception, alike the other members of Mimosoideae.