Pollination biology of the Galápagos endemic, Tournefortia rufo‐sericea (Boraginaceae)

Tournefortia rufo‐sericea is an endemic member of the Galápagos angiosperm flora. Although not uncommon within the archipelago, its status is presently listed as vulnerable and, as such, a complete knowledge of its pollination biology may prove useful in preventing its decline. Pollination experiments, flower‐visitor observations, nectar and fluorescence studies, as well as pollen : ovule ratio and pollen size studies were included in this investigation. The small, white flowers of this species set fruit via open pollination (81%), autonomous self‐pollination (80%), diurnal pollination (80%), and nocturnal pollination (85%). Ants are the most common visitor to the flowers of this species, primarily during the day, whereas beetles and moths make visits at night. A small amount of nectar is presumably produced, as moths are often seen probing the corollas. Experiments with fluorescent dust did not support interflower pollen movement. The pollen : ovule ratio was 4972 : 1, which suggests xenogamy, and the mean pollen size was 21 µm. Despite the pollen : ovule ratio, it appears that this species exhibits a breeding strategy of facultative autogamy, in which the majority of flowers set fruit via autonomous self‐pollination, but limited outcrossing may occur when pollinators are available. Conservation efforts for T. rufo‐sericea should focus on the control or eradication of exotic species. © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 21–31.