Hummingbird pollination in Salvia haenkei (Lamiaceae) lacking the typical lever mechanism

Abstract

While in most Salvia species pollen is transferred by the `staminal lever mechanism', in some species the `levers' are inactive. This is also found in the bird pollinated S. haenkei from Bolivia. To understand pollen transfer in a species lacking the lever mechanism we carried out field investigations and confirmed our observations by means of morphometric measurements of both the flowers and museum skins of the observed hummingbird species. The tubular corolla forces the birds (Sappho sparganura, Colibri coruscans, Patagona gigas, Oreotrochilus adela) into a specific position thereby causing pollen transfer from the exserted pollen-sacs to the bird's feathers and bills. The staminal levers are well developed but cannot be moved because the sterile arms are closely attached to the upper face of the corolla leaving no space for any movement. We assume that the reduction of the lever mechanism reflects an adaptation to bird pollination.