You can find these two growing side by side; the lovely and evocative Jack-in-the-Pulpit, and the evil poison ivy.

Both follow the leaves-of-three way of leafing out.

The Jack-in-the-Pulpit leaves have a line that runs around just inside the edge of the leaf, so that the veins don’t reach the edge of the leaf.

Poison ivy veins go right to the leaf edge.

Also, the center leaf of Jack-in-the-Pulpit is pointed where it meets its stem, whereas poison ivy’s center leaf is usually quite fat at its base.

(Plant ID apps would know the difference between these two easily… but first ya gotta realize that you are looking at two different plants!)