Pinguicula (Butterwort):
Habitat:
The Pinguicula genus is comprised of 102 species, of which 50% are endemic to Mexico, while other species grow in Europe, North America and Africa. Owing to the broad range of climate zones in which they grow, representatives of the Pinguicula are categorised into two different groups. The first group encompasses temperate growth forms which, instead of blossoming upon finishing the creation of their vegetative rosette, develop hibernacula during winter and have a high degree of hardiness. They typically inhabit headwater regions with calcareous soil. The second group consists of species with tropical growth forms, which usually don't undergo any cold spells. These species finish the creation of their vegetative rosette with blossoms in summer to then gradually become succulent winter rosettes that help them overcome potential droughts.
Cultivation:
The Pinguicula is probably the easiest carnivorous plant in cultivation, and therefore the best recommendation for beginners. Especially the Mexican species with larger rosettes are very frequent in garden centers, for example the Pinguicula moranensis or the Pinguicula agnata. Species with smaller rosettes, Pinguicula esseriana or Pinguicula gypsicola are less frequent, yet they have recently been getting more attention as well. All of these are tropical species and don't require much sun nor space, while high temperatures and direct sunlight during summer should be avoided as much as possible. In semi-shade places they feel most comfortable and they also enjoy some degree of waterlogging. At the same time, the humidity should range between 60-80%. Tropical growth forms like to be cultivated in a dry soil during winter without any moist, because in this way their more compact winter rosettes grow better. The soil composition itself should be more alcaline without using sphagnum. Instead, quartz sand, perlites or vermiculites should be mixed together so that in early spring the water absorption will be facilitated. Temperate species, for example the Pinguicula vulgaris or the Pinguicula lutea, have similar requirements, and they are ideally cultivated outdoors in a mini bog. They like consistent wetness and don't have any particular sunlight demands; whether sunny or shadowy, they adjust very well to the weather conditions. Many temperate species are not in cultivation, however, because they require calcareous soil, which is provided best in open land.
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Trap mechanism:
Butterwort is coated with glands whose secretions lend the leaf surface a greasy looks. When insects, usually flies up to 3mm in size, become ensnarled in the mucilage upon landing, this particular spot of the leaf surface will slightly indent to create a temporary "stomach" in which the digestive juices concentrate for the purpose of enhanced prey decomposition. The catching glands on the leaf surface are one-off, which means that once prey has been fully decomposed within some leaf area no further prey can be caught here. Along the leaf margin many Pinguicula species are also capable of partially furling over their prey; therefore, the Pinguicula is counted among the active adhesive traps despite not being able to move their tentacles. In various orchid stands the butterwort is used as a biological pest controller of fungus gnats. But also at home they are a very reliable carnivorous plant to catch undesirable fruit flies. On a final note it is worth mentioning that the Mexican species offered in garden centers don't develop their mucus coating before early spring, because during winter they instead grow tiny leaves owing to the fact that winter time in Mexico is characterised by an insect-poor arid climate.
Much Love and Light,
Alex
Literature inspiration: Kosmos Garten: Fleischfressende Pflanzen