Butterworts

Butterworts, L. Pinguicula, are one of 13 species of insectivorous plants that grow in Minnesota, the others being sundews (4 species), bladderworts (7), and pitcherplants (1). Butterworts, and nearly all plants that supplement their nutriment by consuming insects, reside in damp environments with low nitrogen levels, such as swamps or wet rock surfaces. In Minnesota, butterworts inhabit very specific microclimates in northern Minnesota. One such place is along Lake Superior (see Butterwort Cliffs Scientific and Natural Area). The photograph above is a butterwort sheltered within a niche in the exposed bedrock of the Superior shoreline near Gooseberry falls. Exoskeletal husks of consumed insects blot its leaves like tiny ink spots.

The dietary proclivities of butterworts were first documented in Charles Darwin’s Insectivorous plants (New York, D. Appleton & Co., 1875), in which he writes: “I was led to investigate the habits of this plant by being told by Mr. W. Marshall that on the mountains of Cumberland many insects adhere to the leaves.” Butterwort leaves glisten with adhesive and digestive fluids, the smell of which insects apparently find, to their demise, alluring. Once an insect has alighted upon the leaves of the butterwort and cannot prise itself from their surface, the throes of the struggle that ensues incite the plant to secrete additional adhesives, as the edges of the foliage curl up around the insect.

The first written description of butterworts was published in Austrian naturalist Vitus Auslasser’s treatise on medicinal herbs, Macer de Herbarium, in 1479. Auslasser notes the mucilagenous surface of the leaves, calling the plant a “lard herb” (zitroch kraut). The Latin genus name Pinguicula comes later, from the Swiss naturalist Conrad Gesner. In his 1561 work Horti Germaniae, Gesner, like Auslasser, describes the leaves as “fat” – “pinguia et tenera folia” (“fat and tender foliage” – pinguia from the Latin pinguis, meaning fat). The “fat” of these appellations persists in the English common name “butterwort.”

Wort (or wurt or wyrt) is an Old English word meaning plant, or herb, and has similarly antiquated cognates in other European languages (wurz in Old High German, for example). Wort persists in modern English usage as the second element in compound words used as common names for some plants, like Spleenwort, Lungwort, Bruisewort, etc. Such plant names are associated with the Doctrine of Signatures, a Christian metaphysical hermeneutic in which resemblance figures as the basis of interpretation. For example, the Spleenwort I referred to above is a fern (Asplenium) which bears spores on the undersides of its leaves in a pattern that was thought to resemble the spleen – thus the fern came to be used for treating medical conditions associated with the spleen. The doctrine insinuates affinity between (seemingly) categorically distinct things. The uses to which such plants might be put are not limited to the medicinal – resemblance in the Doctrine of Signatures serves as index to all the host of Creation in which God inscribed His mark. The name Mugwort (Artemisia vulgaris), for example, is thought to be derived from the habit of using the herb in the brewing of beer. Although the name “butterwort” does not suggest its use as medicinal herb, it is nevertheless named for that to which it bears a resemblance (fat), and perhaps a use to which it was once put as well.

Linnaeus wrote about butterworts in Flora Lapponica – his survey of the flora of Lappland, and in his journal of 1732, written during his time traveling above the arctic circle and living among Sápmelaš (or “Sami”) tribes when he was in his mid-twenties. These narratives are decidedly “ethnobotanical” in nature – the term was coined much later in 1895, by John William Harshberger. In Linnaeus’ illustration below, Pinguicula is marked 2. and 3. The other two images are from the cover of Flora Lapponica. In one, a depiction of the bucolic backdrop to the ambitious notetaking of Linnaeus’ youth – natives floral, faunal, and human.

Among his notes, Linnaeus describes how butterwort leaves were used by Sami to make a yogurt-like fermented milk called filmjölk. Butterwort leaves had for centuries been in use in northern Europe and parts of the Alps for the purpose of making various types of fermented milk. Most of the Norwegian names for butterworts reflect this use of the leaves as a curdling agent: tettebugge (thickening old man), tettegress (thickening grass), vuodjalasta (butter leaf), istegras (curdle grass), melkekrossen (milk cross), etc. Likewise, the word “yogurt” (yoğurt) refers to thickness – it is derived from Turkish words, yoğun (“dense”) and/or yoğurmak (“to make dense”), in reference to the methods which produce it.

Filmjölk contains unique strains of bacteria unlike those found in commercial yogurt, which is cultured with Lactobacillus and Streptococcus thermophilus species. Filmjölk requires the species Lactococcus and Leuconostoc. Fil (Filmjölk), is the popular name for what is now a product sold commercially in 1-litre packages in Sweden.

In Norway, Tjukkmjolk, is likewise commerically available. It is actually the first food product from Norway with a “controlled origin” label. It is made from cultures obtained from Pinguicula vulgaris.