Reproductive ecology of three rare North American Pinguicula species

Pinguicula (Lentibulariaceae) is a genus of more than 100 carnivorous plant species. A handful of comprehensive studies have examined the reproductive ecology of these species, mostly in Europe and none in the USA. During 2013–2016 different aspects of the reproductive ecology of P. ionantha, P. lutea and P. planifolia were studied at multiple locations in the Florida Panhandle, USA. All three species are of conservation concern within the study region and some aspects of their reproductive ecology may be contributing to their rarity. For all species, we conducted breeding system studies investigating xenogamy vs. autogamy, self-incompatibility vs. self-compatibility, pollen:ovule ratios, flower phenology and longevity, and pollinator visitation, as well as fruit and seed set differences among populations. All three Pinguicula species were determined to be xenogamous and self-compatible, although the pollen:ovule ratios were extremely low. In addition, these species have floral nastic movements and flower longevity that ranges from 2 to 3 weeks depending on the species. Hymenoptera was identified as the primary group of pollinators visiting all species, although observed visitation events were low. All three Pinguicula species had extremely high levels of fruit set and seed set. Worldwide, Pinguicula species share similar breeding system and reproductive patterns. The rare status of P. ionantha, P. lutea and P. planifolia is more likely due to their ecological requirements, demographics and/or patterns of genetic diversity, than reproduction. This work is among the first and most comprehensive associated with the reproductive ecology of North American Pinguicula.