Flower structure and intraspecific variability in Geoffroea decorticans (Fabaceae)

Abstract

The objective was to characterize floral structure and to analyze intraspecific flower variability in G. decorticans (Gillies ex Hok. et Arn.) Burkart, from the view of its reproductive biology. In order to this, three populations of G. decorticans from central Argentina were studied considering the morphology and anatomy of reproductive floral traits. The quantified variables were: size of the complete flower; corolla, anther cycles and gynoecium length; anther-stigma separation; number of pollen grains and ovules per flower; and number and size of nectarial stomata. The protogynous flowers are small (less than 1 cm), yellow, and they are arranged in racemes. The stamens (9 + 1) form two pentamerous cycles of different length. The gynoecium is composed by a hairy ovary with a style variable in length. Thus, the stigma can be observed over or under the position of the anthers. The nectary is persistent. Its upper part is located at the base of the staminal tube whereas its base is fused with the receptacle. Gynoecium and style length were positively correlated, whereas both flower size and filament length were inversely correlated to anther-stigma separation. In a broad sense, flower structure appears to be stable in G. decorticans. However, some characters were variable such as flower size and the number of nectarial estomata. This flower traits variation may affect pollination and/or seed set.