The bloodroot (Sanguinaria canadensis) is said to be quite variable in flower and leaf. I shot this one in the Arboretum last Saturday, where it is shown displaying its frill in a threatening manner.
Although this type of behavior is typical of certain animals, it's not at all common in the plant kingdom.
The juice of the bloodroot is red and poisonous, but at least it doesn't spit. The other plants nearby nonetheless felt threatened.