Butter Cup is a familiar wildflower, they prefer to grow in open waste ground and acidic soils throughout North America, not to mention the middle of my lawn. They grow all over the BC coast.
Their irritant qualities are probably the basis of the children’s game in which one child presses a buttercup to the sensitive skin just below the chin, to see if you like butter. The slight redness caused by such casual contact is supposed, in the game, to indicate a butter lover. Prolonged contact can have more uncomfortable results. The breakdown of a glycoside releases a blister-inducing juice, which can have an effect on the sensitive skin of children.
Generally, buttercups have yellow cup-like flowers and deeply divided leaves, which may or may not be fuzzy. The poison is located in the sap, flowers, seeds, and leaves of the plants, with the greatest concentration of the toxin occurring in vigorous growing new shoots.
Buttercups typically cause irritation and blistering of the skin if handled, and if swallowed, an intense burning of the mouth and digestive tract, followed by nausea and convulsions. Luckily, the plant tastes so bad that victims rarely get to this state, but gardeners should be sure to wear gloves before weeding out the buttercups.