Pollen limitation, reproductive success and flowering frequency in single-flowered plants

1. Flowering plants exhibit striking interspecific and intraspecific variation in flower number, which strongly influences the reproductive success of animal-pollinated plants. However, the reproductive consequences of producing a single flower are poorly understood.
2. Here, we test if plants producing a single flower have a reproductive disadvantage compared to plants producing multiple flowers by combining field investigation of five deceptive orchids and a survey of published literature. Pollen limitation was estimated by comparing fruit production between hand pollination and open pollination. Flowering frequency was monitored over years to assess the potential advantage of producing a single flower. 3. Both single- and multiple-flowered species suffered strong pollen limitation. However, single-flowered species had significantly lower fruit set and produced fewer seeds per individual, though they had a significantly higher pollen removal than species with multiple flowers. A phyl...