The Common Butterwort, Pinguicula vulgaris, is a carnivorous plant and member of the Lentibulariaceae family, which are all carnivorous, it is one of several carnivorous plant species found in the British isles which include Bladderworts and Sundews.
Its common name is thought to come from its traditional use as an agent to help milk curdle into butter. Its scientific name, Pinguicula, comes from the Latin word pinguis, meaning ‘oily’, presumably because of the sticky substance the plant secretes from its leaves, and vulgaris simply means ‘common’. It is, however, considerably less common now then it was when it was named in the 1500s by the Swedish naturalist Conrad Gesner.
Range
In the British isles it is now found predominantly in Northern Ireland, Wales and Scotland with smaller, isolated populations in the Northwest of England, Norfolk, the Yorkshire wolds, the Chilterns and a few other places.
Evolved to ensnare
Common Butterwort is a perennial plant, meaning it grows back in the same place year after year, and produces a low, star-shaped rosette of waxy looking, yellowy green leaves with curled up edges, which can be up to 15cm across.
These leaves secrete an extremely sticky substance from special appendages on the surface called ‘peduncular glands’ which are comprised of a small number of cells resting on a single stalk cell. Droplets of this attract wandering animacules on the search for food or water which then become ensnared.
Next a set of cells which lay flat on the leaf’s surface, which form ‘sessile glands’, trigger a response in the whole leaf which causes it to curl up at the edges, further trapping the doomed insect, and produce digestive enzymes. These enzymes break down the softer parts of the insect’s body and the resulting nutritional juices are absorbed through holes in the leaf’s surface called ‘cuticulor’ holes, only the hard chitinous eco-skeleton of the insect is left.
The Butterwort, like other carnivorous plants, evolved to ensnare insects to supplement its diet, as its preferred habitats are usually on soils which are lacking in essential minerals, particularly Nitrogen and Phosphorous, these tending to be acidic peat bogs and moorlands in the British isles, it can survive without these minerals, by photosynthesis alone, but will not produce flowers without them.
Flowering and fruiting
Flowers are produced from about May to July on the end of red/ brown stalks, up to 20cm high, and are a beautiful violet colour with 5 unequally sized petals which fuse at the base into a tube with a backward spur, similar to that of a Violet.
It does seem rather hypocritical of the plant to rely upon the very insects it would eat in order to be pollinated but it does considerately grow it’s flowers as far away from the deadly leaves as it can I suppose!
The fruits are like a little, pointed light-brown nut and open at the tip, splitting in 2 as they ripen to release the seeds, which are spread by the wind, the seed pods open in dry weather but will close again if it gets damp, re-opening when the weather reaches optimal conditions of dry and windy.
A B-H
June 2024
Northwest Nature and History 