Enzymatic secretions from glands on the upper surface of the leaves aid in digestion of insects and other little creatures that try to land or stroll on the sticky surface. The yellowish green color of the leaves (which curl inward along the margin) enhances the slippery, buttery aspect, and the leaves are said to coagulate milk. “Butterwort” is a doubly appropriate common name.
All species found in Pinguicula
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. January 29, 2020. https://michiganflora.net/genus.aspx?id=Pinguicula.