Buttercup leaves

Buttercups are often included in lists of poisonous plants because, during its flowering stage, the plant contains a toxin, protoanemonin, which is released when the plant is crushed. It is a volatile, bitter, yellow oil that is prone to spontaneous polymerization to yield innocuous anemonin. Protoanemonin is degraded by drying, so hay containing dried buttercups is safe. Rabbits do not eat buttercup leaves and there are no reports of buttercup poisoning in rabbits. There are reports in other species in situations where buttercups are all that is left in overgrazed fields and the animals eat them out of desperation.