Ranunculus is a large genus of about 400 species of plants in the Ranunculaceae. It includes the buttercups, spearworts, water crowfoots and the lesser celandine (but not the greater celandine of the poppy family Papaveraceae).
They are mostly herbaceous perennials with bright yellow or white flowers (if white, still with a yellow centre). A few have orange or red flowers and occasionally, as in R. auricomus, petals may be absent. The petals are often highly lustrous, especially in yellow species. Buttercups usually flower in April or May but flowers may be found throughout the summer especially where the plants are growing as opportunistic colonisers, as in the case of garden weeds.
The name Ranunculus is Latin for ‘little frog‘. This probably refers to many species being found near water, like frogs.
All Ranunculus species are poisonous when eaten fresh by cattle, horses, and other livestock, but their acrid taste and the blistering of the mouth caused by their poison means they are usually left uneaten. Poisoning can occur where buttercups are abundant in overgrazed fields where little other edible plant growth is left, and the animals eat them out of desperation. Symptoms include bloody diarrhea, excessive salivation, colic, and severe blistering of the mucous membranes and gastrointestinal tract. When Ranunculus plants are handled, naturally occurring ranunculin is broken down to form protoanemonin, which is known to cause contact dermatitis in humans and care should therefore be exercised in excessive handling of the plants.