Stamina! variation and its possible significance in Commelina benghalensis L. and Commelina caroliniana Walter

摘要

Flowers of Commelina benghalensis L. and Commelina caroliniana Walter are odourless and nectar-less. Therefore, they rely on visual characteristics for attracting pollinators and offer pollen as the only reward. Androecium, the focus of an insect's attention in these species, consists of three fertile and three sterile stamens. The three fertile stamens have two types of anthers. The central one has a bright yellow, long, inwardly curved, versatile anther with a massive connective. The other two are lateral, cryptic, with smaller ovate, straight and basifixed anthers, light grey in C. benghalensis and yellow with a brown streak in C. caroliniana. The sterile stamens or staminodes are bright yellow, variously shaped and borne on slender filaments. They contrast sharply with the blue corolla and attract insects by appearing filled with abundant pollen. To determine the possible significance of this diversity, morphological and functional aspects of the male reproductive organs were worked out and, between and within species comparisons were also made.