About Pinguicula macrophylla Kunth
Pinguicula, commonly called butterworts, are mostly perennial carnivorous plants; the only known annual species are P. sharpii, P. takakii, P. crenatiloba, and P. pumila. Every butterwort species grows as a stemless rosette. For horticultural convenience, butterworts are divided into two main ecological groups based on their native growing climates, though genetic studies do not support these groupings in a cladistic classification. These two groups are further subdivided based on whether they produce leaves of different forms across their growing season. If summer growth differs in size or shape from early spring growth (for temperate species) or winter growth (for tropical species), the plant is classified as heterophyllous; uniform leaf growth across seasons classifies a species as homophyllous, resulting in a total of four practical horticultural groupings. Tropical butterworts grow in regions with seasonal water scarcity and low-nitrogen acidic soil. They either maintain carnivorous leaves year-round or form a compact winter rosette of fleshy leaves, and they flower when they form a new rosette. Heterophyllous tropical species alternate between carnivorous leaf rosettes in warm seasons and compact rosettes of fleshy non-carnivorous leaves in cool seasons; examples include P. moranensis, P. gypsicola, and P. laxifolia. Homophyllous tropical species produce rosettes of carnivorous leaves of roughly uniform size all year, such as P. gigantea. Temperate butterworts are native to climate zones with cold winters. They form tight, scale-leafed winter resting buds called hibernacula during winter dormancy; during this period, all carnivorous leaves wither, and all roots wither except for those of P. alpina. They flower when they produce their summer rosettes. Heterophyllous temperate species have vegetative and generative rosettes that differ in shape and/or size, as seen in P. lutea and P. lusitanica. Homophyllous temperate species have identical vegetative and generative rosettes, as exhibited by P. alpina, P. grandiflora, and P. vulgaris. Most individual Pinguicula species have very limited natural distributions. Butterworts are distributed across the Northern Hemisphere, with the highest concentration of species in humid mountainous regions of Mexico, Central America, and South America, where populations extend as far south as Tierra del Fuego. Only Australia and Antarctica have no native butterwort species. The genus likely originated in Central America, which is the center of Pinguicula diversity and hosts roughly 50% of all known butterwort species. The two species with the widest distributions, P. alpina and P. vulgaris, grow across most of Europe and North America. Additional species native to North America include P. caerulea, P. ionantha, P. lutea, P. macroceras, P. planifolia, P. primuliflora, P. pumila, and P. villosa. In general, butterworts grow in nutrient-poor soils, most commonly alkaline soils. Some species have adapted to other soil types, including acidic peat bogs, pure gypsum soils, and even vertical rock walls. A small number of species are epiphytes. Many Mexican species commonly grow on mossy banks, rock, and roadsides in oak-pine forests. Pinguicula macroceras ssp. nortensis has been observed growing on hanging dead grasses, while P. lutea grows in pine flatwoods, and species like P. vulgaris grow in fens. All of these habitats are nutrient-poor, which lets butterworts avoid competition with faster-growing canopy-forming species, particularly grasses and sedges. At minimum during their active carnivorous growth stage, butterworts require almost constantly moist or wet habitats. Many Mexican species survive winter drought by losing carnivorous leaves, sprouting succulent leaves, or dying back to onion-like storage structures, and can tolerate completely dry conditions during this dormant period. Required growing moisture can come from a high groundwater table, high humidity, or high precipitation. Unlike many other carnivorous plants that need full sun, many butterworts grow well in partial sun or even full shade. Butterworts are widely cultivated by carnivorous plant enthusiasts. Temperate species and many Mexican butterworts are relatively easy to grow, so they have gained greater popularity among growers. Two of the most widely cultivated plants are hybrid cultivars Pinguicula × 'Sethos' and Pinguicula × 'Weser'; both are crosses between Pinguicula ehlersiae and Pinguicula moranensis, and are used by commercial orchid nurseries to control pests. Butterworts produce a strong bactericide that stops captured insects from rotting during digestion. According to Linnaeus, this bactericidal property has long been known to northern Europeans, who applied butterwort leaves to cattle sores to promote healing. Butterwort leaves were also historically used to curdle milk to make fermented buttermilk-like products called filmjölk in Sweden and tjukkmjølk in Norway.
