All three photographs today are courtesy of Hugh and Carol Nourse@Flickr, of Georgia, USA (original image 1 | original image 2 | original image 3) via the Botany Photo of the Day Flickr Pool). Always appreciated! It was great to unexpectedly meet Hugh in Georgia earlier this year.
The butterworts consist of about eighty recognized species, with the centre of diversity in Central America and northwest South America. Six of the nine species occurring in Canada and the USA are native to the southeastern USA (see: A Synopsis of Pinguicula (Lentibulariaceae) in the Southeastern United States), including the three species featured in today’s photographs: Pinguicula caerulea (blueflower butterwort), Pinguicula lutea (yellow butterwort), and the pink-flowered Pinguicula primuliflora (southern butterwort). These three species are also closely related, all belonging to Pinguicula subgenus Isoloba section Isoloba (all southeastern USA species are assigned to this group).
The insectivorous mechanism of the butterwort leaves is briefly explained in a previous BPotD entry on Pinguicula vulgaris subsp. macroceras.