Flora and Fauna: Extraordinary plant right on our doorstep
Butterbur (Petasites hybridus)
BUTTERBUR is also known as giant rhubarb and early mushrooms.
It is a plant found in wet ground, by river banks and streams, and it spreads to form large colonies by means of its vigorous underground stems.
But it is also dioecious in that the male and female flowers are borne on separate plants. Male plants are common throughout all the UK, and female plants are mostly found further north, in Cheshire, Yorkshire and County Durham.
Female inflorescences have about a 100 flowers, and one or two sterile, nectar-producing flowers; male plants have 20 to 40 sterile flowers, also producing nectar. (In Europe only males are found.)
It is an extraordinary plant, both for its size and its growth habit.
Firstly, the flowers appear early in the year, long before the leaves, and so the nectar-producing blooms are an important source of food for early emerging insects, particularly for bees.
The inflorescences first appear looking a bit like mushrooms – an explanation for the otherwise curious nickname. After that, they expand to look more like untidy hyacinths.
But then the leaves appear, and grow and grow until their hollow stems are two metres high or more; and the 90cm broad leaves are often used by children as umbrellas or parasols, depending on the weather. (The name Petasites was chosen because of the Greek word for a broad brimmed hat.)
But the value of the leaves, and the source of the name butterbur, lies in their hairy undersides.
The leaves were used for wrapping butter and these springy hairs kept the butter buffered and cool so it could be taken to the local market.
There are probably people in Barnard Castle who can still remember butter wrapped in these leaves and being sold in what we now call the Market Cross.
Since medieval times the plant’s qualities have been appreciated.
It was used as a febrifuge (a plant effective against fever) and as an anticonvulsant. The active chemical is called petasin, a terpene (a type of organic compound produced by plants).
It was discovered and isolated in the 1950s and was considered 14 times more effective as an anticonvulsant than previous treatments.
To see Butterbur in all its leafy glory, you need to walk up Deepdale in summer. But to see the early flowers you need go no further than the Green Bridge in February.
Richard Warren is a botanist from Barnard Castle