Pinguicula – the flypaper

Pinguicula sp. under the family of Lentibulariaceae, commonly known as butterwort, and means the little greasy one in Latin. It consists of about 50 species. It is greasy due to the slimy, sticky, and greasy touch of the leaves. “Ping” is not sticking to the common impression of carnivorous plants. They do not have the capability of killing large insects or small mammals with specialized and colorful leaves that differentiated into sophisticated traps. Pinguicula is found worldwide. Pinguicula mostly occurs in Mexico, the Caribbean, the southeastern United States, South America, and temperate North America. They also grow in the Arctic, temperate, and tropical areas of the world in acid or alkaline, wet or damp soil in a humid environment. Some species grow epiphytically on trees like ferns, orchids, or air plants.

Ping is a herbaceous perennial that has delicate colors such as green and pink, fragile rosettes, and bristle leaves terminating in a blunt point. The edge or margin of the leaves exhibits different degrees of rolling in that varying from green to yellowish-green to reddish in color. It has two forms, namely homophylous and heterophyllous. Most Pinguicula is homophyllous that having the same shape and size of the leaves throughout the entire growing period. On the other hand, heterophyllous Pinguicula has a different leaf shape before and after flowering. Pings produce beautiful flowers that form singly on straight leafless scapes or very long flower stalk. Their flower color ranges from shades of yellow, white, blue, and violet to purple.

Pinguicula can be propagated sexually through the cross-pollination of species. Manual cross-pollination can be tedious as the flowers of it is rather small, which often tear open the floral structures during manual pollination. However, successful pollination resulted in the mature seed pods in a week or two. Subsequently, the mature seed pods will then split open to release the seeds after four weeks. Butterwort can be propagated asexually through runners and leaf cuttings. After the plantlets have rooted, they can be separated from the mother plant. Regeneration of plantlets occurred with the removal of whole leaf treated with fungicides and keep the leaves beneath sphagnum moss, about one-third below the moss under high humidity and bright condition, temperature varies according to the species. The more succulent, thick, and watery the leaves, the higher the success rate.

Most Pinguicula species favor moist to very wet acidic soil in high humidity that protected from direct sunlight. Greenhouse with artificial light or indirect sunlight works well for it. As compared to other carnivorous plants, some species of butterwort prefer an alkaline substrate rather than acidic. For hobbyists or home growers, it can be fed with small insects manually such as gnats and tiny springtails. Wingless fruit flies or small ants, or occasionally apply bits of dried insects to their leaves also accepted. The old and brown leaves usually dissolve simply and can be trimmed away. To grow Pinguicula, it’s important to know which division of the butterworts belong to, namely, temperate, tropical, as well as hybrids of temperate and tropical. Temperate butterworts can survive long, cold winters by dying down to small, cone-shaped hibernacula, gemmae, a cone-shaped bud, which commonly known as resting buds. The buds are another alternative for propagating it in which the small baby buds are produced around the base of the mother bud during late winter. For tropical pings, they can survive in a tropical climate that requires a change of forms. When there is warm most of the year and fewer raindrops, the butterwort will turn succulent with large and sticky leaves. A few temperate butterworts occasionally produce a natural hybrid that none is known among warm temperate and tropical species. This might due to artificial hybridization in cultivation for ornamental purposes.

All species of Pinguicula consist of a short vertical stem that gives rise to a basal rosette of thick leaves which are broadly ovate and either lie flat on the ground or stand obliquely upwards. However, even without specialized traps, the leaves of Pinguicula are the most effective in insect trapping mechanisms among carnivorous plants. It is believed that the fungal odor with the nectar-like glistening on the leaves acts as a prey attractant as well as the brilliant red leaf coloration for some species. The greasy surface of the leaves is covered by sticky mucilage. The leaves of butterwort are distinctly buttery or greasy for us, but a deadly glue for small insects. However, under a magnifying lens, the leaf surfaces covered with abundant glandular hairs that are nearly transparent.

The leaf itself functions as flypaper that sticky the insects with the “glue”. The leaves of Pinguicula consist of two types of glands, mainly used for glue by the stalk gland and digestive juice production by the sessile gland. The stalk gland that responsible for glue production is found at the top of each hair produces a small drop of sticky glue similar to that of Drosera. The other gland, the sessile gland stays dry until the prey is caught. Small insects such as fruit flies can be captured. As similar to Drosera, the leaves of Pinguicula will curl up slightly and slowly. The little and slow motion of the leaves are not designed to trap the insects but to form a shallow bowl which contains the digestive fluids and prevent the loss of their prey. This also prevents the nutrient and digestive juices from running off caused by the leaching effect of rainwater. Many butterworts can even “dish” their leaves under prey, thus giving their juices a convenient place to “pool”. In addition, the leaves tend to become distended beneath the spot where larger insects have been trapped. The sessile glands then reabsorb the fluid that rich in nutrients quickly.

Interestingly, butterwort is also used in culinary, especially food processing. For instance, Norwegians created tettemelk, condensed milk by using Pinguicula vulgaris due to its semi-gelatinous property. Apart from that, northern Europeans used the leaves to create a unique curdling effect with the milk of goat to produce ropy and yogurt-like cheese. It also has pharmacological values on relieving sore reindeer teats and promoting healing as the juice of it has anti-bacterial properties.

Further readings:

Temple, P. (1988). Carnivorous plants.

Pietropaolo, J., Pietropaolo, P. A., & James. Pietropaolo. (1999). Carnivorous plants of the world. Timber Press.

Heslop-Harrison, Y. (2004). Pinguicula L. Journal of Ecology92(6), 1071-1118.

Meyers-Rice, B. (2006). Growing carnivorous plants. Timber Press.

Shuka, L., Xhulaj, M., Kashta, L., & Casper, S. J. (2007). The genus Pinguicula (Lentibulariaceae) in Albania—a critical review. Wulfenia14, 15-65.

D’amato, P. (2013). The savage garden, revised: Cultivating carnivorous plants. Ten Speed Press.