1. Meadow Buttercup - Ranunculus acris
2. Cursed Buttercup - Ranunculus lanuginosus (now Ranunculus sceleratus)
The buttercup or anemone (Ranunculus spp.) has a worldwide distribution. The meadow buttercup is probably native to Alaska and Greenland, but it has been a “weedy” plant in North America for as long as Europeans have recorded it. Even though it’s used as a folk medicine in many Native American tribes, the Iroquois are noted to have had issues with it invading squash fields back in the 1700s.
All buttercups have a toxin in them, called protoanemonin or ranunculol, which is activated when the plant is wounded or crushed (as it is in many folk medicines, or when eaten). While it’s not deadly, it causes itching and blisters on the exposed mucosa, and can cause dizziness, nausea, jaundice, and temporary paralysis when ingested.
The Cursed Buttercup has more of this toxin than any other member of the genus, to the point where it can cause rashes and blisters on the skin if you touch damaged leaves.
Deutschlands Flora in Abbildungen.
Johann Georg Sturm, illustrated by Jacob Sturm, 1796.