Which Mexican butterwort grows in gypsum soils near San Luis Potosi?

Pinguicula gypsicola is the Mexican butterwort that grows in gypsum soils near San Luis Potosí.

This insectivorous species is native to a small area west of the city of San Luis Potosí in Mexico. Its name combines Pinguicula with gypsicola, meaning “gypsum-dwelling,” an apt reference to the mineral-rich slopes where it grows. Townshend Stith Brandegee formally described the species in 1911.

Pinguicula gypsicola is heterophyllous, meaning it produces two distinct kinds of leaves. During the wetter summer growing season, its upright, narrow leaves are carnivorous and covered with sticky glands that trap insects and digest them. During the drier winter period, it forms a compact rosette of smaller, non-carnivorous leaves.

The species is easy to confuse with other Mexican butterworts, especially Pinguicula moranensis, which is widespread and commonly cultivated. P. gypsicola is distinguished by its specialized gypsum habitat and narrow distribution. Its purple flowers appear on slender stalks when summer rains begin.