Tansy

Today was the first day of our second round of monitoring at Whitemoor. We were all feeling a bit jaded, having been kept awake by some seriously spectacular thunderstorms during the night. The weather remained hot and sticky for most of the day, though the more or less persistent cloud cover meant that the temperatures never reached the forecast 29C, and by the end of the afternoon the wind was quite blustery.

Most of my photographs were again functional, but I  found this Tansy plant quite appealing. It's moderately common locally, but is especially characteristic of rail embankments and road verges, where its flowers provide a splash of yellow in late summer. The Tansy plant has been used throughout history. For centuries Tansy tea has been prescribed by herbalists to expel worms because it is highly toxic to internal parasites. Furthermore, its toxicity to insects delays spoilage of meat, whilst planting tansy alongside potato repelled the Colorado potato beetle. At one time omelettes were flavoured with Tansy and Tansy cakes were eaten at Easter. In Yorkshire, Tansy and Caraway seeds were traditionally used in biscuits served at funerals.

Despite all these historic uses it's really not advisable to eat Tansy. The volatile oil contains toxic compounds including thujone which can cause convulsions and liver and brain damage, and the amount present varies from plant to plant, making it impossible to calculate safe dosages. better just to enjoy the flowers, which are also attractive to many pollinators.